A radio frequency front-end circuit, a radio frequency system and a communication device

Abstract

The utility model provides a kind of radio frequency front-end circuit, radio frequency system and communication device, can realize using downlink frequency band to emit radio frequency signal, and using TDD duplex mode in uplink frequency band, so that in the uplink time slot of TDD mode, radio frequency signal can be received in uplink frequency band, and radio frequency signal is emitted in downlink frequency band;In the downlink time slot of TDD mode, radio frequency signal can be emitted simultaneously using uplink frequency band and downlink frequency band, significantly improve the utilization of uplink frequency band resource and downlink frequency band, avoid the phenomenon that downlink frequency band resource is insufficient and uplink frequency band is idle under FDD duplex mode.

Description

Technical Field

[0001] This utility model relates to the field of wireless communication technology, and in particular to a radio frequency front-end circuit, a radio frequency system, and a communication device. Background Technology

[0002] Current wireless communication systems include two duplex modes: TDD (Time Division Duplexing) and FDD (Frequency Division Duplexing), which isolate uplink and downlink signal transmissions in the time or frequency domain. In TDD mode, uplink and downlink signals are transmitted "at the same frequency but not at the same time," meaning there is no frequency band distinction, but rather a time slot for uplink and downlink signal transmission. In FDD mode, uplink and downlink signals are transmitted "at the same time but not at the same frequency," meaning uplink and downlink signal transmissions can occur simultaneously, but dedicated frequency bands need to be allocated for each.

[0003] The aforementioned TDD and FDD duplex modes and their corresponding RF front-end circuit designs are both mature and stable, and have been used in various generations of mobile communications such as 3G, 4G, and 5G for many years. However, FDD duplex mode has a significant drawback: in most communication networks, downlink traffic is significantly higher than uplink traffic. This can easily lead to insufficient downlink frequency band resources and low utilization of uplink frequency band resources in FDD mode, resulting in inadequate utilization of uplink and downlink frequency band resources. Utility Model Content

[0004] This utility model provides a radio frequency front-end circuit, a radio frequency system, and a communication device to solve the technical problem that existing FDD-based radio frequency front-end circuits are prone to insufficient downlink frequency band resources and low utilization of uplink frequency band resources.

[0005] To solve the above-mentioned technical problems, the first aspect of the present invention provides a radio frequency front-end circuit, including a first radio frequency transmission link, a first TDD radio frequency transmission link, and a first duplexer;

[0006] The first duplexer has a first port, a second port, and a first antenna port for connecting an antenna;

[0007] The first radio frequency transmission link is used to transmit downlink frequency band transmission signals, and the first radio frequency transmission link is connected to the first port;

[0008] The first TDD radio frequency transmission link is used to transmit uplink frequency band transmit signals or uplink frequency band receive signals, and the first TDD radio frequency transmission link is connected to the second port.

[0009] As a preferred embodiment, the first TDD radio frequency transmission link includes a second radio frequency transmission link, a first radio frequency reception link, and a first circulator;

[0010] The second radio frequency transmitting link is used to transmit the uplink frequency band transmitted signal, and the first radio frequency receiving link is used to transmit the uplink frequency band received signal. The output port of the second radio frequency transmitting link and the input port of the first radio frequency receiving link are connected to the second port through the first circulator. The first circulator is used to connect the second radio frequency transmitting link to the first duplexer and to the first radio frequency receiving link to the first duplexer.

[0011] As a preferred embodiment, the first radio frequency transmission link includes a first radio frequency transmission signal processing module and a first isolator;

[0012] The input port of the first radio frequency transmission signal processing module is used to connect to the downlink frequency band signal transmission end of the radio frequency transceiver, the output port of the first radio frequency transmission signal processing module is connected to one end of the first isolator, and the other end of the first isolator is connected to the first port.

[0013] As a preferred embodiment, the first radio frequency transmission signal processing module includes a first digital-to-analog converter, a first filter, a first power amplifier, and a second power amplifier;

[0014] The input port of the first digital-to-analog converter is used to connect to the downlink frequency band signal transmitting end of the radio frequency transceiver. The output port of the first digital-to-analog converter is connected to the input port of the first filter. The output port of the first filter is connected to the input port of the first power amplifier. The output port of the first power amplifier is connected to the input port of the second power amplifier. The output port of the second power amplifier is connected to one end of the first isolator.

[0015] As a preferred embodiment, the second radio frequency transmission link includes a second digital-to-analog converter, a second filter, a third power amplifier, and a fourth power amplifier;

[0016] The input port of the second digital-to-analog converter is used to connect to the uplink signal transmitter of the RF transceiver. The output port of the second digital-to-analog converter is connected to the input port of the second filter. The output port of the second filter is connected to the input port of the third power amplifier. The output port of the third power amplifier is connected to the input port of the fourth power amplifier. The output port of the fourth power amplifier is connected to the first circulator.

[0017] As a preferred embodiment, the first radio frequency receiving link includes a first radio frequency receiving signal processing module and a first switching module;

[0018] One end of the first switch module is connected to the first circulator, and the other end of the first switch module is connected to the input port of the first radio frequency receiving signal processing module. The output port of the first radio frequency receiving signal processing module is used to connect to the uplink frequency band signal receiving end of the radio frequency transceiver. The first switch module is configured to control the on / off state of the first radio frequency receiving link.

[0019] As a preferred embodiment, the first radio frequency receiving signal processing module includes a first low noise amplifier, a first gain module, and a first analog-to-digital converter;

[0020] The input port of the first low-noise amplifier is connected to the other end of the first switching module, the output port of the first low-noise amplifier is connected to the input port of the first gain module, the output port of the first gain module is connected to the input port of the first analog-to-digital converter, and the output port of the first analog-to-digital converter is used to connect to the uplink signal receiving end of the RF transceiver.

[0021] As a preferred embodiment, the first switch module includes a first single-pole double-throw switch and a first resistor;

[0022] The active terminal of the first single-pole double-throw switch is connected to the first circulator, the first fixed terminal of the first single-pole double-throw switch is connected to the input port of the first radio frequency receiving signal processing module, the second fixed terminal of the first single-pole double-throw switch is connected to one end of the first resistor, and the other end of the first resistor is grounded.

[0023] As a preferred embodiment, the first duplexer has a first filter chamber and a second filter chamber inside, the first port is connected to the first filter chamber, the second port is connected to the second filter chamber, and the first filter chamber and the second filter chamber are combined at the first antenna port; the filter in the first filter chamber is used to filter out out-of-band spurious signals of the downlink transmitted signal, and the filter in the second filter chamber is used to filter out out-of-band spurious signals of the uplink transmitted signal and the uplink received signal.

[0024] A second aspect of this utility model provides a radio frequency front-end circuit, including a first transmit signal receiving link, a third radio frequency transmit link, a second TDD radio frequency transmission link, a second duplexer, and a third duplexer;

[0025] The input port of the first transmit signal receiving link is used to connect to the signal transmitting end of the radio frequency transceiver and to receive downlink frequency band transmit signals and / or uplink frequency band transmit signals; the output port of the first transmit signal receiving link is connected to the third radio frequency transmit link and the second TDD radio frequency transmission link respectively through the second duplexer.

[0026] The third duplexer has a third port, a fourth port, and a second antenna port for connecting an antenna.

[0027] The third radio frequency transmission link is used to transmit the downlink frequency band transmission signal, and the third radio frequency transmission link is connected to the third port;

[0028] The second TDD radio frequency transmission link is used to transmit the uplink frequency band transmit signal or the uplink frequency band receive signal, and the second TDD radio frequency transmission link is connected to the fourth port.

[0029] As a preferred embodiment, the second TDD radio frequency transmission link includes a fourth radio frequency transmission link, a second radio frequency reception link, and a second circulator.

[0030] The fourth radio frequency transmitting link is used to transmit the uplink frequency band transmitted signal, and the second radio frequency receiving link is used to transmit the uplink frequency band received signal. The input port of the fourth radio frequency transmitting link is connected to the output port of the first transmitted signal receiving link through the second duplexer. The output port of the fourth radio frequency transmitting link and the input port of the second radio frequency receiving link are connected to the fourth port through the second circulator. The second circulator is used to connect the fourth radio frequency transmitting link to the third duplexer and to the second radio frequency receiving link to the third duplexer.

[0031] As a preferred embodiment, the first transmit signal receiving link includes a third digital-to-analog converter, a third filter, and a fifth power amplifier;

[0032] The input port of the third digital-to-analog converter is used to connect to the signal transmitting end of the RF transceiver and receive the downlink frequency band transmission signal and the uplink frequency band transmission signal; the output port of the third digital-to-analog converter is connected to the input port of the third filter, the output port of the third filter is connected to the input port of the fifth power amplifier, and the output port of the fifth power amplifier is connected to the third RF transmission link and the fourth RF transmission link respectively through the second duplexer.

[0033] As a preferred embodiment, the third radio frequency transmission link includes a sixth power amplifier and a second isolator;

[0034] The input port of the sixth power amplifier is connected to the output port of the fifth power amplifier through the second duplexer, the output port of the sixth power amplifier is connected to one end of the second isolator, and the other end of the second isolator is connected to the third port.

[0035] As a preferred embodiment, the fourth radio frequency transmission link includes a seventh power amplifier;

[0036] The input port of the seventh power amplifier is connected to the output port of the fifth power amplifier through the second duplexer, and the output port of the seventh power amplifier is connected to the second circulator.

[0037] As a preferred embodiment, the second radio frequency receiving link includes a second radio frequency receiving signal processing module and a second switching module;

[0038] One end of the second switch module is connected to the second circulator, and the other end of the second switch module is connected to the input port of the second radio frequency receiving signal processing module. The output port of the second radio frequency receiving signal processing module is used to connect to the signal receiving end of the radio frequency transceiver. The second switch module is configured to control the on / off state of the second radio frequency receiving link.

[0039] As a preferred embodiment, the second radio frequency receiving signal processing module includes a second low noise amplifier, a second gain module, and a second analog-to-digital converter.

[0040] The input port of the second low-noise amplifier is connected to the other end of the second switching module, the output port of the second low-noise amplifier is connected to the input port of the second gain module, the output port of the second gain module is connected to the input port of the second analog-to-digital converter, and the output port of the second analog-to-digital converter is used to connect to the signal receiving end of the RF transceiver.

[0041] As a preferred embodiment, the second switch module includes a second single-pole double-throw switch and a second resistor;

[0042] The active terminal of the second single-pole double-throw switch is connected to the second circulator, the first fixed terminal of the second single-pole double-throw switch is connected to the input port of the second radio frequency receiving signal processing module, the second fixed terminal of the second single-pole double-throw switch is connected to one end of the second resistor, and the other end of the second resistor is grounded.

[0043] As a preferred embodiment, the second duplexer has a transmit signal input port, a downlink frequency band signal output port, and an uplink frequency band signal output port; the output port of the first transmit signal receiving link is connected to the transmit signal input port, the input port of the third radio frequency transmit link is connected to the downlink frequency band signal output port, and the input port of the fourth radio frequency transmit link is connected to the uplink frequency band signal output port.

[0044] As a preferred embodiment, the second duplexer internally comprises a third filter chamber and a fourth filter chamber. The downlink frequency band signal output port is connected to the third filter chamber, and the uplink frequency band signal output port is connected to the fourth filter chamber. The third filter chamber and the fourth filter chamber are combined at the transmit signal input port. The filter in the third filter chamber is used to filter out out-of-band spurious signals of the downlink frequency band transmit signal, and the filter in the fourth filter chamber is used to filter out out-of-band spurious signals of the uplink frequency band transmit signal.

[0045] As a preferred embodiment, the third duplexer internally comprises a fifth filter chamber and a sixth filter chamber. The third port is connected to the fifth filter chamber, and the fourth port is connected to the sixth filter chamber. The fifth and sixth filter chambers are combined at the second antenna port. The filter in the fifth filter chamber is used to filter out out-of-band spurious signals of the downlink transmitted signal, and the filter in the sixth filter chamber is used to filter out out-of-band spurious signals of the uplink transmitted signal and the uplink received signal.

[0046] A third aspect of this utility model provides a radio frequency front-end circuit, including a fifth radio frequency transmitting link, a third radio frequency receiving link, a switching assembly, a third circulator, and a fourth filter;

[0047] The input port of the fifth RF transmit link is used to connect to the signal transmitting end of the RF transceiver and to receive downlink frequency band transmit signals and / or uplink frequency band transmit signals; the third RF receive link is used to transmit uplink frequency band receive signals; the output port of the fifth RF transmit link and the input port of the third RF receive link are connected to one end of the fourth filter through the third circulator, and the other end of the fourth filter is used to connect to the antenna;

[0048] The third circulator is used to connect the fifth radio frequency transmit link to the fourth filter, and to connect the third radio frequency receive link to the fourth filter;

[0049] The switching component is disposed in the fifth radio frequency transmission link. The switching component is used to select whether to send the downlink frequency band transmission signal and the uplink frequency band transmission signal to the fourth filter, or to send the downlink frequency band transmission signal to the fourth filter.

[0050] As a preferred embodiment, the fifth radio frequency transmission link includes a second transmission signal receiving link, a first radio frequency transmission branch, and a second radio frequency transmission branch; the switching assembly includes a third switching module;

[0051] The input port of the second transmit signal receiving link is used to connect to the signal transmitting end of the RF transceiver and receive the downlink frequency band transmit signal and / or the uplink frequency band transmit signal; the output port of the second transmit signal receiving link is connected to the first RF transmit branch and the second RF transmit branch respectively through the third switch module; the output ports of the first RF transmit branch and the second RF transmit branch are both connected to the third circulator;

[0052] The first radio frequency transmission branch is used to transmit the downlink frequency band transmission signal, and the second radio frequency transmission branch is used to transmit the downlink frequency band transmission signal and the uplink frequency band transmission signal;

[0053] The third switch module is used to select whether to connect the second transmit signal receiving link to the first radio frequency transmit branch, or to connect the second transmit signal receiving link to the second radio frequency transmit branch.

[0054] As a preferred embodiment, the fifth radio frequency transmission link includes a second transmission signal receiving link, a first radio frequency transmission branch, and a second radio frequency transmission branch; the switching assembly includes a fourth switching module;

[0055] The input port of the second transmit signal receiving link is used to connect to the signal transmitting end of the RF transceiver and receive the downlink frequency band transmit signal and / or the uplink frequency band transmit signal; the output port of the second transmit signal receiving link is connected to the first RF transmit branch and the second RF transmit branch respectively; the output ports of the first RF transmit branch and the second RF transmit branch are respectively connected to the third circulator through the fourth switch module;

[0056] The first radio frequency transmission branch is used to transmit the downlink frequency band transmission signal, and the second radio frequency transmission branch is used to transmit the downlink frequency band transmission signal and the uplink frequency band transmission signal;

[0057] The fourth switch module is used to select whether to connect the first radio frequency transmission branch to the third circulator or the second radio frequency transmission branch to the third circulator.

[0058] As a preferred embodiment, the fifth radio frequency transmission link includes a second transmission signal receiving link, a first radio frequency transmission branch, and a second radio frequency transmission branch; the switching assembly includes a third switching module and a fourth switching module;

[0059] The input port of the second transmit signal receiving link is used to connect to the signal transmitting end of the RF transceiver and receive the downlink frequency band transmit signal and / or the uplink frequency band transmit signal; the output port of the second transmit signal receiving link is connected to the first RF transmit branch and the second RF transmit branch respectively through the third switch module; the output ports of the first RF transmit branch and the second RF transmit branch are respectively connected to the third circulator through the fourth switch module.

[0060] The first radio frequency transmission branch is used to transmit the downlink frequency band transmission signal, and the second radio frequency transmission branch is used to transmit the downlink frequency band transmission signal and the uplink frequency band transmission signal;

[0061] The third switch module is used to select whether to connect the second transmit signal receiving link to the first radio frequency transmit branch or to the second transmit signal receiving link; the fourth switch module is used to select whether to connect the first radio frequency transmit branch to the third circulator or to the second radio frequency transmit branch.

[0062] As a preferred embodiment, the third switch module is specifically a third single-pole double-throw switch;

[0063] The movable terminal of the third single-pole double-throw switch is connected to the output port of the second transmit signal receiving link, the first fixed terminal of the third single-pole double-throw switch is connected to the input port of the first radio frequency transmit branch, and the second fixed terminal of the third single-pole double-throw switch is connected to the input port of the second radio frequency transmit branch.

[0064] As a preferred embodiment, the fourth switch module is specifically a fourth single-pole double-throw switch;

[0065] The movable terminal of the fourth single-pole double-throw switch is connected to the third circulator, the first fixed terminal of the fourth single-pole double-throw switch is connected to the output port of the first radio frequency transmission branch, and the second fixed terminal of the fourth single-pole double-throw switch is connected to the output port of the second radio frequency transmission branch.

[0066] As a preferred embodiment, the second transmit signal receive link includes a fourth digital-to-analog converter, a fifth filter, an eighth power amplifier, and a ninth power amplifier;

[0067] The input port of the fourth digital-to-analog converter is used to connect to the signal transmitting end of the RF transceiver and receive the downlink frequency band transmission signal and / or the uplink frequency band transmission signal; the output port of the fourth digital-to-analog converter is connected to the input port of the fifth filter, the output port of the fifth filter is connected to the input port of the eighth power amplifier, the output port of the eighth power amplifier is connected to the input port of the ninth power amplifier, and the output port of the ninth power amplifier is used to connect to the first RF transmission branch and the second RF transmission branch respectively.

[0068] As a preferred embodiment, the first radio frequency transmission branch is provided with a sixth filter, which is used to filter out out-of-band spurious signals of the downlink frequency band transmission signal.

[0069] As a preferred embodiment, the third radio frequency receiving link includes a third radio frequency receiving signal processing module, a fifth switching module, and a seventh filter;

[0070] The input port of the seventh filter is connected to the third circulator, the output port of the seventh filter is connected to one end of the fifth switch module, the other end of the fifth switch module is connected to the input port of the third radio frequency receiving signal processing module, and the output port of the third radio frequency receiving signal processing module is used to connect to the signal receiving end of the radio frequency transceiver.

[0071] The seventh filter is used to filter out out-of-band signals of the uplink frequency band received signals;

[0072] The fifth switch module is configured to control the on / off state of the third radio frequency receiving link.

[0073] As a preferred embodiment, the third radio frequency receiving signal processing module includes a third low-noise amplifier, a third gain module, and a third analog-to-digital converter;

[0074] The input port of the third low-noise amplifier is connected to the other end of the fifth switch module, the output port of the third low-noise amplifier is connected to the input port of the third gain module, the output port of the third gain module is connected to the input port of the third analog-to-digital converter, and the output port of the third analog-to-digital converter is used to connect to the signal receiving end of the RF transceiver.

[0075] As a preferred embodiment, the fifth switch module includes a fifth single-pole double-throw switch and a third resistor;

[0076] The active terminal of the fifth single-pole double-throw switch is connected to the output port of the seventh filter, the first fixed terminal of the fifth single-pole double-throw switch is connected to the input port of the third radio frequency receiving signal processing module, the second fixed terminal of the fifth single-pole double-throw switch is connected to one end of the third resistor, and the other end of the third resistor is grounded.

[0077] As a preferred embodiment, the passband of the fourth filter is an uplink frequency band and a downlink frequency band; wherein, the uplink frequency band is the frequency band in which the uplink transmitted signal and the uplink received signal are located, and the downlink frequency band is the frequency band in which the downlink transmitted signal is located.

[0078] A fourth aspect of this utility model provides a radio frequency system, including a radio frequency transceiver, an antenna, and a radio frequency front-end circuit as described in any of the first aspects; the radio frequency transceiver has an uplink frequency band signal transmitting end, a downlink frequency band signal transmitting end, and an uplink frequency band signal receiving end; the downlink frequency band signal transmitting end is connected to the input port of a first radio frequency transmission link in the radio frequency front-end circuit, the uplink frequency band signal transmitting end is connected to the input port of a first TDD radio frequency transmission link in the radio frequency front-end circuit, and the uplink frequency band signal receiving end is connected to the output port of the first TDD radio frequency transmission link; the antenna is connected to the first antenna port of a first duplexer in the radio frequency front-end circuit.

[0079] A fifth aspect of this utility model provides a radio frequency system, including a radio frequency transceiver, an antenna, and a radio frequency front-end circuit as described in any of the second aspects; the radio frequency transceiver has a signal transmitting end and a signal receiving end; the signal transmitting end is connected to the input port of a first transmit signal receiving link in the radio frequency front-end circuit, and the signal receiving end is connected to the output port of a second TDD radio frequency transmission link in the radio frequency front-end circuit; the antenna is connected to the second antenna port of a third duplexer in the radio frequency front-end circuit.

[0080] A sixth aspect of this utility model provides a radio frequency system, including a radio frequency transceiver, an antenna, and a radio frequency front-end circuit as described in any of the third aspects; the radio frequency transceiver has a signal transmitting end and a signal receiving end; the signal transmitting end is connected to the input port of a fifth radio frequency transmitting link in the radio frequency front-end circuit, and the signal receiving end is connected to the output port of a third radio frequency receiving link in the radio frequency front-end circuit; the antenna is connected to the other end of a fourth filter in the radio frequency front-end circuit.

[0081] A seventh aspect of this utility model provides a communication device, including a radio frequency system as described in any one of the fourth to sixth aspects.

[0082] Compared with the prior art, the beneficial effect of this utility model embodiment is that it can transmit radio frequency signals using the downlink frequency band, while adopting TDD duplex mode in the uplink frequency band. Thus, in the uplink time slot of TDD mode, it can receive radio frequency signals in the uplink frequency band and transmit radio frequency signals in the downlink frequency band; in the downlink time slot of TDD mode, it can transmit radio frequency signals using both the uplink and downlink frequency bands simultaneously, which significantly improves the utilization rate of uplink and downlink frequency band resources and avoids the phenomenon of insufficient downlink frequency band resources and idle uplink frequency band in FDD duplex mode. Attached Figure Description

[0083] Figure 1 This is a schematic diagram of a preferred embodiment of the first radio frequency front-end circuit in this utility model;

[0084] Figure 2 This is a schematic diagram of another preferred embodiment of the first radio frequency front-end circuit in this utility model;

[0085] Figure 3 This is a schematic diagram of another preferred embodiment of the first radio frequency front-end circuit in this utility model;

[0086] Figure 4 This is a schematic diagram of a preferred embodiment of the second type of radio frequency front-end circuit in this utility model;

[0087] Figure 5 This is a schematic diagram of another preferred embodiment of the second type of radio frequency front-end circuit in this utility model;

[0088] Figure 6 This is a schematic diagram of another preferred embodiment of the second type of radio frequency front-end circuit in this utility model;

[0089] Figure 7 This is a schematic diagram of a preferred embodiment of the third type of radio frequency front-end circuit in this utility model;

[0090] Figure 8 This is a schematic diagram of another preferred embodiment of the third type of radio frequency front-end circuit in this utility model;

[0091] Figure 9 This is a schematic diagram of another preferred embodiment of the third type of radio frequency front-end circuit in this utility model;

[0092] Figure 10 This is a schematic diagram of another preferred embodiment of the third type of radio frequency front-end circuit in this utility model;

[0093] Figure 11 This is a schematic diagram of another preferred embodiment of the third type of radio frequency front-end circuit in this utility model;

[0094] Figure 12 This is a schematic diagram of the radio frequency system in this utility model;

[0095] Wherein, 1. First RF transmit link; 2. First TDD RF transmission link; 3. First duplexer; 4. Second RF transmit link; 5. First RF receive link; 6. First circulator; 7. Second duplexer; 8. Third RF transmit link; 9. Second TDD RF transmission link; 10. Third duplexer; 11. Fourth RF transmit link; 12. Second RF receive link; 13. Second circulator; 14. Fifth RF transmit link; 15. Third RF receive link; 16. Third circulator; 17. 18. Fourth filter; 19. Second transmit signal receive link; 20. Third switch module; 21. First RF transmit branch; 22. Second RF transmit branch; 23. Fourth switch module; 101. First digital-to-analog converter; 102. First filter; 103. First power amplifier; 104. Second power amplifier; 105. First isolator; 401. Second digital-to-analog converter; 402. Second filter; 403. Third power amplifier; 404. Fourth power amplifier; 405. First circulator; 501. First single-pole double-throw switch; 502. First resistor; 503. First low-noise amplifier; 504. First gain module; 505. First analog-to-digital converter; 601. Third digital-to-analog converter; 602. Third filter; 603. Fifth power amplifier; 801. Sixth power amplifier; 802. Second isolator; 1101. Seventh power amplifier; 1102. Second single-pole double-throw switch; 1103. Second resistor; 1104. Second low-noise amplifier; 1105. Second gain module ; 1106, Second Analog-to-Digital Converter; 1801, Fourth Digital-to-Analog Converter; 1802, Fifth Filter; 1803, Eighth Power Amplifier; 1804, Ninth Power Amplifier; 2001, Sixth Filter; 1501, Seventh Filter; 1502, Fifth Single-Pole Double-Throw Switch; 1503, Third Resistor; 1504, Third Low-Noise Amplifier; 1505, Third Gain Module; 1506, Third Analog-to-Digital Converter; 100, RF Transceiver; 200, RF Front-End Circuit; 300, Antenna. Detailed Implementation

[0096] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0097] Please see Figure 1The first aspect of this utility model provides a radio frequency front-end circuit, including a first radio frequency transmission link 1, a first TDD radio frequency transmission link 2, and a first duplexer 3;

[0098] The first duplexer 3 has a first port, a second port, and a first antenna port for connecting an antenna;

[0099] The first radio frequency transmission link 1 is used to transmit downlink frequency band transmission signals, and the first radio frequency transmission link 1 is connected to the first port;

[0100] The first TDD radio frequency transmission link 2 is used to transmit uplink frequency band transmit signals or uplink frequency band receive signals, and the first TDD radio frequency transmission link 2 is connected to the second port.

[0101] It is worth noting that, in order to fully utilize uplink and downlink frequency band resources, this embodiment combines the characteristics of both TDD and FDD duplex modes. The uplink frequency band in the original FDD duplex mode is modified to use a TDD duplex mode that divides uplink and downlink usage by time, while the downlink frequency band in the original FDD duplex mode is still used only for downlink services, serving as an SDL (Supplementary Down Link) mode. In this TDD+SDL mode, the relatively idle uplink frequency band in the original FDD duplex mode can also be used for downlink service transmission in the TDD downlink time slot, significantly improving the utilization efficiency of the uplink and downlink frequency bands. Based on this, this embodiment proposes a radio frequency front-end circuit, including a first radio frequency transmit link 1, a first TDD radio frequency transmission link 2, and a first duplexer 3.

[0102] Specifically, the first radio frequency transmission link 1 is only used to transmit downlink frequency band transmission signals, so the first radio frequency transmission link 1 always operates in the downlink frequency band, which is the same as the downlink working mode in the original FDD duplex mode. The input port of the first radio frequency transmission link 1 is used to connect to the downlink frequency band signal transmitting end of the radio frequency transceiver to receive and transmit downlink service data located in the downlink frequency band.

[0103] Furthermore, the first TDD RF transmission link 2 adopts TDD duplex mode for RF signal transmission. It is used to transmit uplink transmit signals or uplink receive signals in different working time slots. Understandably, in the uplink time slot of TDD mode, the first TDD RF transmission link 2 is used to transmit uplink receive signals to output them to the uplink signal receiving end of the RF transceiver. At this time, downlink service data can still be transmitted through the first RF transmit link 1. In the downlink time slot of TDD mode, the first TDD RF transmission link 2 is used to transmit uplink transmit signals received from the uplink signal transmitting end of the RF transceiver. If there is too much downlink service data and insufficient uplink frequency band resources, the first RF transmit link 1 can still be used to transmit downlink service data, supplementing the downlink and significantly improving the utilization rate of uplink and downlink frequency band resources. This avoids the phenomenon of insufficient downlink frequency band resources and idle uplink frequency bands in FDD duplex mode.

[0104] Furthermore, in this embodiment, the first RF transmit link 1 and the first TDD RF transmission link 2 are respectively connected to the first port and the second port of the first duplexer 3. It can be understood that the first duplexer 3 supports filtering of downlink transmit signals, uplink transmit signals, and uplink receive signals to achieve out-of-band suppression of signals within the receive / transmit frequency range. Then, the first duplexer 3 also has a first antenna port for connecting an antenna, thereby transmitting downlink transmit signals and / or uplink transmit signals to the antenna, or receiving uplink receive signals received by the antenna.

[0105] As a preferred embodiment, the first TDD radio frequency transmission link 2 includes a second radio frequency transmission link 4, a first radio frequency reception link 5, and a first circulator 4056;

[0106] The second RF transmitting link 4 is used to transmit the uplink frequency band transmission signal, and the first RF receiving link 5 is used to transmit the uplink frequency band reception signal. The output port of the second RF transmitting link 4 and the input port of the first RF receiving link 5 are connected to the second port through the first circulator 4056. The first circulator 4056 is used to connect the second RF transmitting link 4 to the first duplexer 3 and to connect the first RF receiving link 5 to the first duplexer 3.

[0107] Specifically, such as Figure 2As shown, the first TDD radio frequency transmission link 2 in this embodiment further includes a second radio frequency transmission link 4, a first radio frequency reception link 5, and a first circulator 4056. It can be understood that the input port of the second radio frequency transmission link 4 is used to connect to the uplink frequency band signal transmitting end of the radio frequency transceiver, thereby receiving and transmitting the uplink frequency band transmission signal; while the output port of the first radio frequency reception link 5 is used to connect to the uplink frequency band signal receiving end of the radio frequency transceiver, thereby outputting the uplink frequency band reception signal to the radio frequency transceiver. Since the second radio frequency transmission link 4 and the first radio frequency reception link 5 share the uplink frequency band resources, in order to achieve unidirectional transmission of radio frequency signals and ensure that the second radio frequency transmission link 4 and the first radio frequency reception link 5 can work normally and do not interfere with each other when sharing the uplink frequency band resources, this embodiment uses the first circulator 4056 to select different links to connect with the first duplexer 3. Specifically, in the uplink time slot of TDD mode, the uplink frequency band is only used to transmit uplink received signals. Therefore, the first circulator 4056 connects the first RF receiving link 5 with the first duplexer 3, so that the uplink received signal passing through the first duplexer 3 will not mistakenly enter the second RF transmitting link 4. In the downlink time slot of TDD mode, the uplink frequency band is only used to transmit uplink transmitted signals. Therefore, the first circulator 4056 connects the second RF transmitting link 4 with the first duplexer 3, so that the uplink transmitted signal transmitted in the second RF transmitting link 4 will not mistakenly enter the first RF receiving link 5, thus achieving transmit / receive isolation in TDD mode.

[0108] As a preferred embodiment, the first radio frequency transmission link 1 includes a first radio frequency transmission signal processing module and a first isolator 105;

[0109] The input port of the first radio frequency transmission signal processing module is used to connect to the downlink frequency band signal transmission end of the radio frequency transceiver. The output port of the first radio frequency transmission signal processing module is connected to one end of the first isolator 105, and the other end of the first isolator 105 is connected to the first port.

[0110] Specifically, the first RF transmission link 1 in this embodiment further includes a first RF transmission signal processing module and a first isolator 105. It is worth noting that the first RF transmission signal processing module receives the downlink frequency band transmission signal emitted by the RF transceiver and processes the downlink frequency band transmission signal, including filtering and signal amplification, to ensure that the downlink frequency band transmission signal meets the transmission requirements and is transmitted stably and effectively. The processed downlink frequency band transmission signal is transmitted to the first duplexer 3 via the first isolator 105. It is understood that the first isolator 105 ensures unidirectional transmission of the downlink frequency band transmission signal. In the first RF transmission link 1, signal transmission may encounter impedance mismatch, resulting in reflected signals. The first isolator 105 effectively prevents reflected signals from returning to the first RF transmission signal processing module and causing interference, ensuring that the downlink frequency band transmission signal can be stably transmitted to the first duplexer 3. Furthermore, by preventing reflected signals from returning to the first RF transmission signal processing module, the first isolator 105 protects the devices in the first RF transmission signal processing module and ensures the stable operation of the entire RF front-end circuit.

[0111] As a preferred embodiment, the first radio frequency transmission signal processing module includes a first digital-to-analog converter 101, a first filter 102, a first power amplifier 103, and a second power amplifier 104;

[0112] The input port of the first digital-to-analog converter 101 is used to connect to the downlink frequency band signal transmitting end of the radio frequency transceiver. The output port of the first digital-to-analog converter 101 is connected to the input port of the first filter 102. The output port of the first filter 102 is connected to the input port of the first power amplifier 103. The output port of the first power amplifier 103 is connected to the input port of the second power amplifier 104. The output port of the second power amplifier 104 is connected to one end of the first isolator 105.

[0113] Specifically, such as Figure 3As shown, since the downlink frequency band signal emitted by the RF transceiver is a digital signal, it needs to be converted into an analog signal to ensure the smooth transmission of downlink service data. Therefore, in this embodiment, the first digital-to-analog converter 101 is used to convert the received downlink frequency band analog signal into a downlink frequency band digital signal to form a downlink frequency band transmission signal. Further, the first filter 102, as a bandpass filter, filters the downlink frequency band transmission signal from the first digital-to-analog converter 101. It can filter out signals within the downlink frequency band and prevent interference signals from other frequency bands from passing through, making the signal entering the subsequent power amplifier purer and avoiding interference signals being amplified together during the amplification process, thereby affecting the communication quality. Further, the first power amplifier 103, as a preamplifier, performs preliminary amplification of the downlink frequency band transmission signal to increase the power of the downlink frequency band transmission signal, so as to meet the power requirements of the subsequent second power amplifier 104 for the input signal and prepare for further amplification of the downlink frequency band transmission signal. The amplification function of the first power amplifier 103 enhances the driving capability of the downlink transmitted signal, enabling it to better resist transmission loss during subsequent transmission. Furthermore, the second power amplifier 104, as the final stage amplifier, needs to amplify the downlink transmitted signal to a sufficient power level to meet transmission requirements and ensure that the downlink transmitted signal can be effectively transmitted through the antenna. In this process, the second power amplifier 104 needs to possess high power output capability and good linearity to guarantee the quality of the amplified signal and avoid distortion of the downlink transmitted signal.

[0114] As a preferred embodiment, the second radio frequency transmission link 4 includes a second digital-to-analog converter 401, a second filter 402, a third power amplifier 403, and a fourth power amplifier 404;

[0115] The input port of the second digital-to-analog converter 401 is used to connect to the uplink signal transmitter of the RF transceiver. The output port of the second digital-to-analog converter 401 is connected to the input port of the second filter 402. The output port of the second filter 402 is connected to the input port of the third power amplifier 403. The output port of the third power amplifier 403 is connected to the input port of the fourth power amplifier 404. The output port of the fourth power amplifier 404 is connected to the first circulator 4056.

[0116] Specifically, such as Figure 3As shown, since the uplink frequency band signal emitted by the RF transceiver is a digital signal, it needs to be converted into an analog signal to ensure the smooth transmission of downlink service data. Therefore, the second digital-to-analog converter 401 in this embodiment is used to convert the received uplink frequency band analog signal into an uplink frequency band digital signal to form an uplink frequency band transmission signal. Further, the second filter 402, as a bandpass filter, filters the uplink frequency band transmission signal from the second digital-to-analog converter 401. It can filter out signals within the uplink frequency band and prevent interference signals from other frequency bands from passing through, making the signal entering the subsequent power amplifier purer and avoiding interference signals being amplified together during the amplification process, thereby affecting the communication quality. Further, the third power amplifier 403, as a preamplifier, performs preliminary amplification of the uplink frequency band transmission signal to increase the power of the uplink frequency band transmission signal in order to meet the input signal power requirements of the subsequent fourth power amplifier 404 and prepare for further amplification of the uplink frequency band transmission signal. The amplification function of the third power amplifier 403 enhances the driving capability of the uplink transmitted signal, enabling it to better resist transmission loss during subsequent transmission. Furthermore, the fourth power amplifier 404, as the final stage amplifier, needs to amplify the uplink transmitted signal to a sufficient power level to meet transmission requirements and ensure that the uplink transmitted signal can be effectively transmitted through the antenna. In this process, the fourth power amplifier 404 needs to possess high power output capability and good linearity to guarantee the quality of the amplified signal and avoid distortion of the uplink transmitted signal.

[0117] As a preferred embodiment, the first radio frequency receiving link 5 includes a first radio frequency receiving signal processing module and a first switching module;

[0118] One end of the first switch module is connected to the first circulator 4056, and the other end of the first switch module is connected to the input port of the first radio frequency receiving signal processing module. The output port of the first radio frequency receiving signal processing module is used to connect to the uplink frequency band signal receiving end of the radio frequency transceiver. The first switch module is configured to control the on / off state of the first radio frequency receiving link 5.

[0119] Specifically, in this embodiment, the first radio frequency receiving link 5 further includes a first radio frequency receiving signal processing module and a first switching module. The first switching module is configured to control the on / off state of the first radio frequency receiving link 5. It can be understood that during the uplink time slot in TDD mode, the first switching module controls the first radio frequency receiving link 5 to be on, so that the uplink frequency band received signal can be transmitted to the first radio frequency receiving signal processing module through the first switching module. Then, the first radio frequency receiving signal processing module processes the uplink frequency band received signal, enabling it to be received by the radio frequency transceiver and processed subsequently. During the downlink time slot in TDD mode, since the uplink frequency band is only used for transmitting radio frequency signals, the first radio frequency receiving link 5 is not working. To prevent the uplink frequency band transmitted signal from mistakenly entering the first radio frequency receiving link 5, the first switching module controls the first radio frequency receiving link 5 to be off, directing any possible transmission leakage signal to the grounded matching impedance, protecting the first radio frequency receiving link 5 from interference.

[0120] As a preferred embodiment, the first radio frequency receiving signal processing module includes a first low noise amplifier 503, a first gain module 504, and a first analog-to-digital converter 505;

[0121] The input port of the first low-noise amplifier 503 is connected to the other end of the first switching module, the output port of the first low-noise amplifier 503 is connected to the input port of the first gain module 504, the output port of the first gain module 504 is connected to the input port of the first analog-to-digital converter 505, and the output port of the first analog-to-digital converter 505 is used to connect to the uplink frequency band signal receiving end of the RF transceiver.

[0122] Specifically, such as Figure 3 As shown, the first radio frequency (RF) received signal processing module in this embodiment further includes a first low-noise amplifier 503, a first gain module 504, and a first analog-to-digital converter 505. It is worth noting that since the uplink received signal received by the antenna experiences significant attenuation during transmission, resulting in a weak signal strength when it reaches the RF front-end circuit, the first low-noise amplifier 503 is first used to amplify the uplink received signal to bring it to a processable level. Furthermore, the first low-noise amplifier 503 introduces very low noise during signal amplification, a crucial characteristic. Introducing excessive noise while amplifying the uplink received signal would degrade its quality, affecting subsequent demodulation and decoding, and ultimately reducing communication quality. The first low-noise amplifier 503 ensures a high signal-to-noise ratio for the amplified uplink received signal, laying the foundation for accurate signal reconstruction.

[0123] Furthermore, the first gain module 504 can further adjust the gain of the uplink received signal after initial amplification by the first low-noise amplifier 503. The first gain module 504 can finely adjust the gain of the uplink received signal according to the actual needs of the circuit, ensuring that the strength of the uplink received signal reaches the input level range required by the subsequent first analog-to-digital converter 505. Under different communication environments and signal strengths, the first gain module 504 can flexibly adjust the gain to ensure the stability and reliability of the system. In addition, the uplink received signal will experience certain losses during transmission due to transmission lines, filters, and other components. The first gain module 504 can compensate for these losses, ensuring that the uplink received signal maintains sufficient strength throughout the entire first RF receiving link 5, successfully completing the conversion from analog to digital signals and subsequent processing.

[0124] Furthermore, since the signal received by the RF transceiver is a digital signal, this embodiment needs to use the first analog-to-digital converter 505 to convert the uplink frequency band received signal, which is an analog signal, into a digital signal, and then output it to the uplink frequency band signal receiving end of the RF transceiver.

[0125] As a preferred embodiment, the first switch module includes a first single-pole double-throw switch 501 and a first resistor 502;

[0126] The active terminal of the first single-pole double-throw switch 501 is connected to the first circulator 4056, the first fixed terminal of the first single-pole double-throw switch 501 is connected to the input port of the first radio frequency receiving signal processing module, the second fixed terminal of the first single-pole double-throw switch 501 is connected to one end of the first resistor 502, and the other end of the first resistor 502 is grounded.

[0127] Specifically, such as Figure 3 As shown, the first switch module in this embodiment further includes a first single-pole double-throw switch 501 and a first resistor 502. It can be understood that during the uplink time slot in TDD mode, the active terminal of the first single-pole double-throw switch 501 is connected to the first fixed terminal, enabling the first RF receiving link 5 to conduct, thus allowing the uplink frequency band received signal to be transmitted to the first RF receiving signal processing module via the first single-pole double-throw switch 501. During the downlink time slot in TDD mode, since the uplink frequency band is only used for RF signal transmission, the first RF receiving link 5 is not working. To prevent the uplink frequency band transmitted signal from mistakenly entering the first RF receiving link 5, the active terminal of the first single-pole double-throw switch 501 is connected to the second fixed terminal, causing the first RF receiving link 5 to disconnect, guiding any potential transmission leakage signal to the grounded first resistor 502, protecting the first RF receiving link 5 from interference.

[0128] As a preferred embodiment, the first duplexer 3 has a first filter chamber and a second filter chamber inside, the first port is connected to the first filter chamber, the second port is connected to the second filter chamber, and the first filter chamber and the second filter chamber are combined at the first antenna port; the filter in the first filter chamber is used to filter out out-of-band spurious signals of the downlink frequency band transmitted signal, and the filter in the second filter chamber is used to filter out out-of-band spurious signals of the uplink frequency band transmitted signal and the uplink frequency band received signal.

[0129] Specifically, in this embodiment, the first duplexer 3 has a first filter chamber and a second filter chamber inside, so that the first duplexer 3 has a specific filtering structure for the uplink and downlink frequency bands. The filter in the first filter chamber is used to filter out out-of-band spurious signals of the downlink frequency band transmitted signal, that is, to allow the downlink frequency band transmitted signal to pass through while blocking the uplink frequency band signal. The filter in the second filter chamber is used to filter out out-of-band spurious signals of the uplink frequency band transmitted signal and the uplink frequency band received signal, that is, to allow the uplink frequency band transmitted signal and the uplink frequency band received signal to pass through while blocking the downlink frequency band signal.

[0130] The radio frequency front-end circuit provided in this embodiment of the utility model can transmit radio frequency signals using the downlink frequency band by utilizing the first radio frequency transmission link 1, and can adopt TDD duplex mode in the uplink frequency band through the first TDD radio frequency transmission link 2. Thus, in the uplink time slot of TDD mode, radio frequency signals can be received in the uplink frequency band and transmitted in the downlink frequency band; in the downlink time slot of TDD mode, radio frequency signals can be transmitted simultaneously using the uplink and downlink frequency bands, which significantly improves the utilization rate of uplink and downlink frequency band resources and avoids the phenomenon of insufficient downlink frequency band resources and idle uplink frequency band in FDD duplex mode.

[0131] It is worth noting that the RF front-end circuit provided in the first aspect of this utility model has an unbalanced requirement for the number of chip I / O interfaces of the RF transceiver. As mentioned above, the RF transceiver needs to be configured with a downlink signal transmitter, an uplink signal transmitter, and an uplink signal receiver, i.e., two transmit ports and one receive port, as well as corresponding internal circuitry. In fact, the number of transmit and receive interfaces in mature RF transceiver products is often the same. Therefore, using the RF front-end circuit design of the first aspect will result in existing receive interfaces being idle, or the need to customize the RF transceiver chip. In addition, the RF front-end circuit design of the first aspect requires two independent RF transmit links, each of which needs to include components such as filters and power amplifiers, with the power amplifier being the most expensive component. Considering that the uplink and downlink frequency bands are very close in FDD mode, the operating bandwidth of RF devices can generally be covered simultaneously. Therefore, using two independent RF transmit links is not economical. Based on this, this utility model proposes another RF front-end circuit.

[0132] Please see Figure 4 The second aspect of this utility model provides a radio frequency front-end circuit, including a first transmit signal receiving link, a third radio frequency transmit link 8, a second TDD radio frequency transmission link 9, a second duplexer 7, and a third duplexer 10;

[0133] The input port of the first transmit signal receiving link is used to connect to the signal transmitting end of the radio frequency transceiver and to receive downlink frequency band transmit signals and / or uplink frequency band transmit signals; the output port of the first transmit signal receiving link is connected to the third radio frequency transmit link 8 and the second TDD radio frequency transmission link 9 respectively through the second duplexer 7.

[0134] The third duplexer 10 has a third port, a fourth port, and a second antenna port for connecting an antenna.

[0135] The third radio frequency transmission link 8 is used to transmit the downlink frequency band transmission signal, and the third radio frequency transmission link 8 is connected to the third port;

[0136] The second TDD radio frequency transmission link 9 is used to transmit the uplink frequency band transmit signal or the uplink frequency band receive signal, and the second TDD radio frequency transmission link 9 is connected to the fourth port.

[0137] Specifically, in this embodiment, the input port of the first transmit signal receiving link is used to connect to the signal transmitting end of the RF transceiver and receive downlink and / or uplink transmit signals. It is understood that by using the RF front-end circuit in this embodiment, the RF transceiver can be configured with only one signal transmitting end, which can transmit both downlink and uplink transmit signals. Compared to the RF front-end circuit in the first aspect, this avoids the problem of existing receiving interfaces being idle or the need to customize RF transceiver chips. Furthermore, the output port of the first transmit signal receiving link is connected to the third RF transmit link 8 and the second TDD RF transmission link 9 via the second duplexer 7. It is understandable that the third RF transmit link 8 is only used to transmit downlink frequency band transmit signals, so the third RF transmit link 8 always operates in the downlink frequency band, which is the same as the downlink operating mode in the original FDD duplex mode. The input port of the third RF transmit link 8 is connected to the second duplexer 7. Since the first transmit signal receive link may transmit downlink frequency band transmit signals and uplink frequency band transmit signals at the same time, the second duplexer 7 enables the downlink frequency band transmit signals to be transmitted to the third RF transmit link 8, while blocking the transmission of uplink frequency band transmit signals to the third RF transmit link 8.

[0138] The second TDD RF transmission link 9 uses TDD duplex mode for RF signal transmission. It is used to transmit uplink transmit signals or uplink receive signals in different time slots. Specifically, in the uplink time slot of TDD mode, the second TDD RF transmission link 9 is used to transmit uplink receive signals to output them to the signal receiving end of the RF transceiver. At this time, downlink service data can still be transmitted sequentially through the first transmit signal receiving link and the third RF transmit link 8. Therefore, the signal transmitting end of the RF transceiver only emits downlink transmit signals, and the first transmit signal receiving link only receives and transmits downlink transmit signals. In the downlink time slot of TDD mode, the second TDD RF transmission link 9 is used for... The uplink transmit signal received from the signal transmitter of the RF transceiver is transmitted. If there is too much downlink service data and the uplink frequency band resources are insufficient, the first transmit signal receiving link and the third RF transmit link 8 can be used to transmit downlink service data, which plays a supplementary role to the downlink. Therefore, the signal transmitter of the RF transceiver can simultaneously send downlink and uplink transmit signals, while the first transmit signal receiving link simultaneously receives and transmits downlink and uplink transmit signals. At this time, for the second TDD RF transmission link 9, the second duplexer 7 enables the uplink transmit signal to be transmitted to the second TDD RF transmission link 9, while blocking the downlink transmit signal from being transmitted to the second TDD RF transmission link 9. Of course, if there are sufficient uplink frequency band resources, the signal transmitting end of the RF transceiver can also only transmit uplink frequency band signals, and the first transmit signal receiving link can only receive and transmit uplink frequency band signals. This embodiment does not make specific limitations here. This significantly improves the utilization rate of uplink and downlink frequency band resources and avoids the phenomenon of insufficient downlink frequency band resources and idle uplink frequency band in FDD duplex mode.

[0139] Furthermore, in this embodiment, the third RF transmit link 8 and the second TDD RF transmission link 9 are respectively connected to the third port and the fourth port of the third duplexer 10. It is understood that the third duplexer 10 supports filtering of downlink transmit signals, uplink transmit signals, and uplink receive signals to achieve out-of-band suppression of signals within the receive / transmit frequency range. Then, the third duplexer 10 also has a second antenna port for connecting an antenna, thereby transmitting downlink transmit signals and / or uplink transmit signals to the antenna, or receiving uplink receive signals received by the antenna.

[0140] As a preferred embodiment, the second TDD radio frequency transmission link 9 includes a fourth radio frequency transmission link 11, a second radio frequency reception link 12, and a second circulator 13;

[0141] The fourth RF transmit link 11 is used to transmit the uplink frequency band transmit signal, and the second RF receive link 12 is used to transmit the uplink frequency band receive signal. The input port of the fourth RF transmit link 11 is connected to the output port of the first transmit signal receive link through the second duplexer 7. The output port of the fourth RF transmit link 11 and the input port of the second RF receive link 12 are connected to the fourth port through the second circulator 13. The second circulator 13 is used to connect the fourth RF transmit link 11 to the third duplexer 10 and to connect the second RF receive link 12 to the third duplexer 10.

[0142] Specifically, such as Figure 5 As shown, the second TDD radio frequency transmission link 9 in this embodiment further includes a fourth radio frequency transmission link 11, a second radio frequency reception link 12, and a second circulator 13. It can be understood that the input port of the fourth radio frequency transmission link 11 is connected to the output port of the first transmit signal reception link via a second duplexer 7. It is used to transmit uplink frequency band transmit signals. Since the first transmit signal reception link may simultaneously transmit downlink frequency band transmit signals and uplink frequency band transmit signals, the second duplexer 7 enables the uplink frequency band transmit signal to be transmitted to the fourth radio frequency transmission link 11 while simultaneously blocking the downlink frequency band transmit signal from being transmitted to the fourth radio frequency transmission link 11. The output port of the second radio frequency reception link 12 is used to connect to the signal receiving end of the radio frequency transceiver, thereby outputting the uplink frequency band receive signal to the radio frequency transceiver. Since the fourth RF transmit link 11 and the second RF receive link 12 share uplink frequency band resources, in order to achieve unidirectional transmission of RF signals and ensure that the fourth RF transmit link 11 and the second RF receive link 12 can work normally and do not interfere with each other when sharing uplink frequency band resources, this embodiment uses a second circulator 13 to select different links to connect with the third duplexer 10. Specifically, in the uplink time slot of TDD mode, the uplink frequency band is only used to transmit uplink frequency band received signals. Therefore, the second circulator 13 connects the second RF receive link 12 with the third duplexer 10, so that the uplink frequency band received signal passing through the third duplexer 10 will not mistakenly enter the fourth RF transmit link 11. In the downlink time slot of TDD mode, the uplink frequency band is only used to transmit uplink frequency band transmitted signals. Therefore, the second circulator 13 connects the fourth RF transmit link 11 with the third duplexer 10, so that the uplink frequency band transmitted signal transmitted in the fourth RF transmit link 11 will not mistakenly enter the second RF receive link 12, thus achieving transmit-receive isolation in TDD mode.

[0143] Furthermore, due to the isolation provided by the second duplexer 7 and the third duplexer 10, out-of-band spurious signals (specifically, spurious signals falling into the uplink frequency band) of the downlink transmitted signal will not enter the second radio frequency receiving link 12.

[0144] As a preferred embodiment, the first transmit signal receiving link includes a third digital-to-analog converter 601, a third filter 602, and a fifth power amplifier 603;

[0145] The input port of the third digital-to-analog converter 601 is used to connect to the signal transmitting end of the radio frequency transceiver and to receive the downlink frequency band transmission signal and the uplink frequency band transmission signal; the output port of the third digital-to-analog converter 601 is connected to the input port of the third filter 602, the output port of the third filter 602 is connected to the input port of the fifth power amplifier 603, and the output port of the fifth power amplifier 603 is connected to the third radio frequency transmission link 8 and the fourth radio frequency transmission link 11 respectively through the second duplexer 7.

[0146] Specifically, such as Figure 6 As shown, the first transmit signal receiving link in this embodiment further includes a third digital-to-analog converter 601, a third filter 602, and a fifth power amplifier 603. It is understood that since both the uplink and downlink signals emitted by the RF transceiver are digital signals, they need to be converted into analog signals to ensure smooth transmission of downlink service data. Therefore, the third digital-to-analog converter 601 in this embodiment is used to convert the received downlink analog signal into a downlink digital signal to form a downlink transmit signal, and to convert the received uplink analog signal into an uplink digital signal to form an uplink transmit signal. Furthermore, the third filter 602, as a bandpass filter, filters the downlink transmit signal and / or uplink transmit signal from the first digital-to-analog converter 101. The filtering process can filter out signals within the uplink and downlink frequency bands, preventing interference signals from other frequency bands from passing through, making the signals entering the subsequent power amplifiers cleaner, and avoiding interference signals being amplified along with the signal during the amplification process, thereby affecting communication quality. Furthermore, the first power amplifier 103, as a pre-amplifier, performs preliminary amplification on the downlink frequency band transmitted signal and / or the uplink frequency band transmitted signal, increasing the power of the downlink frequency band transmitted signal and / or the uplink frequency band transmitted signal, preparing for further amplification of the downlink frequency band transmitted signal and the uplink frequency band transmitted signal in the third radio frequency transmission link 8 and the fourth radio frequency transmission link 11.

[0147] As a preferred embodiment, the third radio frequency transmission link 8 includes a sixth power amplifier 801 and a second isolator 802;

[0148] The input port of the sixth power amplifier 801 is connected to the output port of the fifth power amplifier 603 through the second duplexer 7. The output port of the sixth power amplifier 801 is connected to one end of the second isolator 802, and the other end of the second isolator 802 is connected to the third port.

[0149] Specifically, such as Figure 6 As shown, the third radio frequency transmission link 8 in this embodiment further includes a sixth power amplifier 801 and a second isolator 802. It can be understood that the downlink frequency band transmission signal transmitted to the third radio frequency transmission link 8 has already undergone amplification by the pre-amplifier. In order to further amplify the downlink frequency band transmission signal to a sufficient power level to meet the transmission requirements and ensure that the downlink frequency band transmission signal can ultimately be effectively transmitted through the antenna, the third radio frequency transmission link 8 in this embodiment utilizes the sixth power amplifier 801 as the final stage amplifier to further amplify the downlink frequency band transmission signal.

[0150] Furthermore, the second isolator 802 ensures unidirectional transmission of downlink frequency band transmit signals. In the third RF transmit link 8, signal transmission may encounter impedance mismatch, resulting in reflected signals. The second isolator 802 can effectively prevent reflected signals from returning to the first transmit signal receive link and causing interference, ensuring that the downlink frequency band transmit signal can be stably transmitted to the third duplexer 10. In addition, by preventing reflected signals from returning to the first transmit signal receive link, the second isolator 802 can protect the devices in the first transmit signal receive link and ensure the stable operation of the entire RF front-end circuit.

[0151] As a preferred embodiment, the fourth radio frequency transmission link 11 includes a seventh power amplifier 1101;

[0152] The input port of the seventh power amplifier 1101 is connected to the output port of the fifth power amplifier 603 through the second duplexer 7, and the output port of the seventh power amplifier 1101 is connected to the second circulator 13.

[0153] Specifically, the fourth radio frequency transmission link 11 in this embodiment further includes a seventh power amplifier 1101. It can be understood that the uplink frequency band transmission signal transmitted to the fourth radio frequency transmission link 11 has already been amplified by the pre-amplifier. In order to further amplify the uplink frequency band transmission signal to a sufficient power level to meet the transmission requirements and ensure that the uplink frequency band transmission signal can be effectively transmitted through the antenna, the fourth radio frequency transmission link 11 in this embodiment uses the seventh power amplifier 1101 as the final stage amplifier to further amplify the uplink frequency band transmission signal.

[0154] Furthermore, since the preliminary filtering and amplification of the uplink and downlink transmitted signals are completed in the first transmitted signal receiving link, the third RF transmitted link 8 only needs to include one final stage amplifier and isolator, and the fourth RF transmitted link 11 only needs to include one final stage amplifier. Compared with the RF front-end circuit provided in the first aspect, each independent transmitted link must include complete filters, preamplifiers and final stage amplifiers, etc. The RF front-end circuit in this embodiment can reduce some components, thereby reducing the overall cost of the RF front-end circuit.

[0155] As a preferred embodiment, the second radio frequency receiving link 12 includes a second radio frequency receiving signal processing module and a second switching module;

[0156] One end of the second switch module is connected to the second circulator 13, and the other end of the second switch module is connected to the input port of the second radio frequency receiving signal processing module. The output port of the second radio frequency receiving signal processing module is used to connect to the signal receiving end of the radio frequency transceiver. The second switch module is configured to control the on / off state of the second radio frequency receiving link 12.

[0157] Specifically, the second RF receiving link 12 in this embodiment further includes a second RF receiving signal processing module and a second switching module. The second switching module is configured to control the on / off state of the second RF receiving link 12. Understandably, during the uplink time slot in TDD mode, the second switching module controls the second RF receiving link 12 to be on, so that the uplink frequency band received signal can be transmitted to the second RF receiving signal processing module via the second switching module. Then, the second RF receiving signal processing module processes the uplink frequency band received signal, enabling it to be received by the RF transceiver and processed subsequently. During the downlink time slot in TDD mode, since the uplink frequency band is only used for RF signal transmission, the second RF receiving link 12 is not working. To prevent the uplink frequency band transmitted signal from mistakenly entering the second RF receiving link 12, the second switching module controls the second RF receiving link 12 to be off, directing any potential transmission leakage signal to the grounded matching impedance, protecting the second RF receiving link 12 from interference.

[0158] As a preferred embodiment, the second radio frequency receiving signal processing module includes a second low noise amplifier 1104, a second gain module 1105, and a second analog-to-digital converter 1106.

[0159] The input port of the second low-noise amplifier 1104 is connected to the other end of the second switch module, the output port of the second low-noise amplifier 1104 is connected to the input port of the second gain module 1105, the output port of the second gain module 1105 is connected to the input port of the second analog-to-digital converter 1106, and the output port of the second analog-to-digital converter 1106 is used to connect to the signal receiving end of the radio frequency transceiver.

[0160] Specifically, such as Figure 6 As shown, the second RF receiving signal processing module in this embodiment further includes a second low-noise amplifier 1104, a second gain module 1105, and a second analog-to-digital converter 1106. It is worth noting that since the uplink received signal received by the antenna experiences significant attenuation during transmission, resulting in a weak signal strength when it reaches the RF front-end circuit, the second low-noise amplifier 1104 is first used to amplify the uplink received signal to bring it to a processable level. Furthermore, the second low-noise amplifier 1104 introduces very low noise during signal amplification, a crucial characteristic. Introducing excessive noise while amplifying the uplink received signal would degrade its quality, affecting subsequent demodulation and decoding, and ultimately reducing communication quality. The second low-noise amplifier 1104 ensures a high signal-to-noise ratio for the amplified uplink received signal, laying the foundation for accurate original signal reconstruction.

[0161] Furthermore, the second gain module 1105 can further adjust the gain of the uplink received signal after initial amplification by the second low-noise amplifier 1104. The second gain module 1105 can finely adjust the gain of the uplink received signal according to the actual needs of the circuit, ensuring that the strength of the uplink received signal reaches the input level range required by the subsequent second analog-to-digital converter 1106. Under different communication environments and signal strengths, the second gain module 1105 can flexibly adjust the gain to ensure the stability and reliability of the system. In addition, the uplink received signal will experience certain losses during transmission due to transmission lines, filters, and other components. The second gain module 1105 can compensate for these losses, ensuring that the uplink received signal maintains sufficient strength throughout the entire second RF receiving link 12, successfully completing the conversion from analog to digital signals and subsequent processing.

[0162] Furthermore, since the signal received by the RF transceiver is a digital signal, this embodiment needs to use the second analog-to-digital converter 1106 to convert the uplink frequency band received signal, which is an analog signal, into a digital signal, and then output it to the signal receiving end of the RF transceiver.

[0163] As a preferred embodiment, the second switch module includes a second single-pole double-throw switch 1102 and a second resistor 1103;

[0164] The active terminal of the second single-pole double-throw switch 1102 is connected to the second circulator 13, the first fixed terminal of the second single-pole double-throw switch 1102 is connected to the input port of the second radio frequency receiving signal processing module, the second fixed terminal of the second single-pole double-throw switch 1102 is connected to one end of the second resistor 1103, and the other end of the second resistor 1103 is grounded.

[0165] Specifically, such as Figure 6 As shown, the second switch module in this embodiment further includes a second single-pole double-throw switch 1102 and a second resistor 1103. It can be understood that during the uplink time slot in TDD mode, the active terminal of the second single-pole double-throw switch 1102 is connected to the first fixed terminal, enabling the second RF receiving link 12 to conduct, thus allowing the uplink frequency band received signal to be transmitted to the second RF receiving signal processing module via the second single-pole double-throw switch 1102. During the downlink time slot in TDD mode, since the uplink frequency band is only used for RF signal transmission, the second RF receiving link 12 is not working. To prevent the uplink frequency band transmitted signal from mistakenly entering the second RF receiving link 12, the active terminal of the second single-pole double-throw switch 1102 is connected to the second fixed terminal, causing the second RF receiving link 12 to disconnect, guiding any potential transmission leakage signal to the grounded second resistor 1103, protecting the second RF receiving link 12 from interference.

[0166] As a preferred embodiment, the second duplexer 7 has a transmit signal input port, a downlink frequency band signal output port, and an uplink frequency band signal output port; the output port of the first transmit signal receiving link is connected to the transmit signal input port, the input port of the third RF transmit link 8 is connected to the downlink frequency band signal output port, and the input port of the fourth RF transmit link 11 is connected to the uplink frequency band signal output port.

[0167] As a preferred embodiment, the second duplexer 7 has a third filter chamber and a fourth filter chamber inside. The downlink frequency band signal output port is connected to the third filter chamber, and the uplink frequency band signal output port is connected to the fourth filter chamber. The third filter chamber and the fourth filter chamber are combined at the transmit signal input port. The filter in the third filter chamber is used to filter out out-of-band spurious signals of the downlink frequency band transmit signal, and the filter in the fourth filter chamber is used to filter out out-of-band spurious signals of the uplink frequency band transmit signal.

[0168] Specifically, in this embodiment, the second duplexer 7 has a third filter chamber and a fourth filter chamber inside, so that the second duplexer 7 has a specific filtering structure for the uplink and downlink frequency bands. The filter in the third filter chamber is used to filter out out-of-band spurious signals of the downlink frequency band transmitted signal, that is, it allows the downlink frequency band transmitted signal to pass through while blocking the uplink frequency band signal. The filter in the fourth filter chamber is used to filter out out-of-band spurious signals of the uplink frequency band transmitted signal, that is, it allows the uplink frequency band transmitted signal to pass through while blocking the downlink frequency band signal.

[0169] As a preferred embodiment, the third duplexer 10 internally comprises a fifth filter chamber and a sixth filter chamber. The third port is connected to the fifth filter chamber, and the fourth port is connected to the sixth filter chamber. The fifth and sixth filter chambers are combined at the second antenna port. The filter in the fifth filter chamber is used to filter out out-of-band spurious signals of the downlink transmitted signal, and the filter in the sixth filter chamber is used to filter out out-of-band spurious signals of the uplink transmitted signal and the uplink received signal.

[0170] Specifically, in this embodiment, the third duplexer 10 has a fifth filter chamber and a sixth filter chamber inside, so that the third duplexer 10 has specific filtering structures for the uplink and downlink frequency bands. The filter in the fifth filter chamber is used to filter out out-of-band spurious signals of the downlink frequency band transmitted signal, that is, to allow the downlink frequency band transmitted signal to pass through while blocking the uplink frequency band signal. The filter in the sixth filter chamber is used to filter out out-of-band spurious signals of the uplink frequency band transmitted signal and the uplink frequency band received signal, that is, to allow the uplink frequency band transmitted signal and the uplink frequency band received signal to pass through while blocking the downlink frequency band signal.

[0171] The radio frequency front-end circuit provided in this embodiment of the utility model can transmit radio frequency signals using the downlink frequency band by utilizing the third radio frequency transmission link 8, and can adopt TDD duplex mode in the uplink frequency band through the second TDD radio frequency transmission link 9. Thus, in the uplink time slot of TDD mode, radio frequency signals can be received in the uplink frequency band and transmitted in the downlink frequency band; in the downlink time slot of TDD mode, radio frequency signals can be transmitted simultaneously using the uplink and downlink frequency bands, which significantly improves the utilization rate of uplink and downlink frequency band resources and avoids the phenomenon of insufficient downlink frequency band resources and idle uplink frequency band in FDD duplex mode.

[0172] Furthermore, by designing a first transmit signal receiving link to receive downlink and / or uplink transmit signals, the RF transceiver can be configured with only one signal transmitter, which can transmit both downlink and uplink transmit signals. This ensures that the number of signal transmitting ports of the RF transceiver is equal to the number of signal receiving ports, avoiding the problem of existing receiving interfaces being idle or the need to customize RF transceiver chips.

[0173] Furthermore, in view of the defects of the radio frequency front-end circuit provided in the first aspect, this utility model embodiment proposes another radio frequency front-end circuit.

[0174] Please see Figure 7 The third aspect of this utility model provides a radio frequency front-end circuit, including a fifth radio frequency transmitting link 14, a third radio frequency receiving link 15, a switching assembly, a third circulator 16, and a fourth filter 17.

[0175] The input port of the fifth RF transmit link 14 is used to connect to the signal transmitting end of the RF transceiver and to receive downlink frequency band transmit signals and / or uplink frequency band transmit signals; the third RF receive link 15 is used to transmit uplink frequency band receive signals; the output port of the fifth RF transmit link 14 and the input port of the third RF receive link 15 are connected to one end of the fourth filter 17 through the third circulator 16, and the other end of the fourth filter 17 is used to connect to an antenna;

[0176] The third circulator 16 is used to connect the fifth radio frequency transmit link 14 to the fourth filter 17, and to connect the third radio frequency receive link 15 to the fourth filter 17.

[0177] The switching component is disposed in the fifth radio frequency transmission link 14. The switching component is used to select whether to send the downlink frequency band transmission signal and the uplink frequency band transmission signal to the fourth filter 17, or to send the downlink frequency band transmission signal to the fourth filter 17.

[0178] Specifically, in this embodiment, the input port of the fifth RF transmit link 14 is used to connect to the signal transmitter of the RF transceiver and receive downlink and / or uplink transmit signals. It is understood that by using the RF front-end circuit in this embodiment, the RF transceiver can be configured with only one signal transmitter, which can transmit both downlink and uplink transmit signals. Compared to the RF front-end circuit in the first aspect, this avoids the problem of existing receiver interfaces being idle or the need to customize the RF transceiver chip. Furthermore, the third RF receive link 15 is used to transmit uplink receive signals. In this embodiment, a switching component is configured in the fifth RF transmit link 14 to form an RF transmission link suitable for TDD+SDL mode with the third RF receive link 15 and the third circulator 16. It is worth noting that during the uplink time slot in TDD mode, the uplink frequency band can only be used to receive RF signals. Therefore, the third RF receiving link 15 is active at this time, used to transmit uplink received signals. Meanwhile, the RF transceiver's signal transmitter only emits downlink transmit signals, and the fifth RF transmitting link 14 only receives and transmits downlink transmit signals. The switching component is used to select which downlink transmit signal to send to the fourth filter 17. However, during the downlink time slot in TDD mode, the uplink frequency band can only be used to transmit RF signals. Therefore, the third RF receiving link 15 is inactive at this time. The signal transmitter of the RF transceiver can simultaneously transmit downlink and uplink signals, avoiding excessive downlink data and insufficient uplink resources. In this case, the downlink band plays a supplementary role to the downlink. The fifth RF transmission link 14 simultaneously receives and transmits downlink and uplink signals. At this time, the switching component is used to select whether to send downlink and uplink signals to the fourth filter 17. This significantly improves the utilization rate of uplink and downlink resources and avoids the phenomenon of insufficient downlink resources and idle uplink resources in FDD duplex mode.

[0179] Furthermore, since the fifth RF transmit link 14 and the third RF receive link 15 share uplink frequency band resources, in order to achieve unidirectional transmission of RF signals and ensure that the fifth RF transmit link 14 and the third RF receive link 15 can work normally and do not interfere with each other when sharing uplink frequency band resources, this embodiment uses a third circulator 16 to select different links to connect with the fourth filter 17. Specifically, in the uplink time slot of TDD mode, the third circulator 16 connects the third RF receive link 15 with the fourth filter 17, so that the uplink frequency band received signal passing through the fourth filter 17 will not mistakenly enter the fifth RF transmit link 14; while in the downlink time slot of TDD mode, the third circulator 16 connects the fifth RF transmit link 14 with the fourth filter 17, so that the downlink frequency band transmit signal and the uplink frequency band transmit signal transmitted in the fifth RF transmit link 14 will not mistakenly enter the third RF receive link 15, thus achieving transmit / receive isolation in TDD mode.

[0180] Furthermore, since the fifth radio frequency transmission link 14 may transmit downlink and uplink transmission signals simultaneously, the fourth filter 17 is a filter that allows both uplink and downlink signals to pass through.

[0181] As a preferred embodiment, the fifth radio frequency transmission link 14 includes a second transmission signal receiving link 18, a first radio frequency transmission branch 20, and a second radio frequency transmission branch 21; the switching assembly includes a third switching module 19;

[0182] The input port of the second transmit signal receiving link 18 is used to connect to the signal transmitting end of the RF transceiver and receive the downlink frequency band transmit signal and / or the uplink frequency band transmit signal; the output port of the second transmit signal receiving link 18 is connected to the first RF transmit branch 20 and the second RF transmit branch 21 respectively through the third switch module 19; the output ports of the first RF transmit branch 20 and the second RF transmit branch 21 are both connected to the third circulator 16;

[0183] The first radio frequency transmission branch 20 is used to transmit the downlink frequency band transmission signal, and the second radio frequency transmission branch 21 is used to transmit the downlink frequency band transmission signal and the uplink frequency band transmission signal;

[0184] The third switch module 19 is used to select whether to connect the second transmit signal receiving link 18 to the first radio frequency transmit branch 20 or to connect the second transmit signal receiving link 18 to the second radio frequency transmit branch 21.

[0185] Specifically, such as Figure 8As shown, the fifth RF transmission link 14 in this embodiment further includes a second transmit signal receiving link 18, a first RF transmission branch 20, and a second RF transmission branch 21, while the switching assembly specifically includes a third switching module 19. The first RF transmission branch 20 is only used to transmit downlink frequency band transmission signals, thus the first RF transmission branch 20 always operates within the downlink frequency band, the same as the downlink operating mode in the original FDD duplex mode. The second RF transmission branch 21 can be used to transmit both downlink and uplink frequency band transmission signals, thus the second RF transmission branch 21 can form a TDD duplex-based transmission link with the third RF receiving link 15. Furthermore, the input port of the second transmit signal receiving link 18 is used to connect to the signal transmitting end of the RF transceiver and receive downlink and / or uplink frequency band transmission signals. Its output port is then connected to the first RF transmission branch 20 and the second RF transmission branch 21 respectively through the third switching module 19. During the uplink time slot in TDD mode, since the uplink frequency band is only used for transmitting uplink received signals, the RF transceiver only outputs downlink transmitted signals. That is, the second transmit signal receiving link 18 only receives downlink transmitted signals. The third switch module 19 then connects the second transmit signal receiving link 18 to the first RF transmit branch 20, and the third circulator 16 connects the first RF transmit branch 20 to the fourth filter 17, and the fourth filter 17 to the third RF receive link 15. This prevents the uplink received signal passing through the fourth filter 17 from mistakenly entering the first RF transmit branch 20 and the second RF transmit branch 21, while the downlink received signal transmitted through the first RF transmit branch 20... The received signal will not mistakenly enter the third RF receiving link 15. In the downlink time slot of TDD mode, since the uplink frequency band is only used to transmit uplink frequency band transmission signals, the RF transceiver can simultaneously transmit downlink frequency band transmission signals and uplink frequency band transmission signals. That is, the second transmit signal receiving link 18 simultaneously receives downlink frequency band transmission signals and uplink frequency band transmission signals. The third switch module 19 selects to connect the second transmit signal receiving link 18 to the second RF transmit branch 21, and the third circulator 16 is used to connect the second RF transmit branch 21 to the fourth filter 17, so that the downlink frequency band transmission signals and uplink frequency band transmission signals transmitted through the second RF transmit branch 21 will not mistakenly enter the third RF receiving link 15.

[0186] As a preferred embodiment, the fifth radio frequency transmission link 14 includes a second transmission signal receiving link 18, a first radio frequency transmission branch 20, and a second radio frequency transmission branch 21; the switching assembly includes a fourth switching module 22;

[0187] The input port of the second transmit signal receiving link 18 is used to connect to the signal transmitting end of the RF transceiver and receive the downlink frequency band transmit signal and / or the uplink frequency band transmit signal; the output port of the second transmit signal receiving link 18 is connected to the first RF transmit branch 20 and the second RF transmit branch 21 respectively; the output ports of the first RF transmit branch 20 and the second RF transmit branch 21 are respectively connected to the third circulator 16 through the fourth switch module 22;

[0188] The first radio frequency transmission branch 20 is used to transmit the downlink frequency band transmission signal, and the second radio frequency transmission branch 21 is used to transmit the downlink frequency band transmission signal and the uplink frequency band transmission signal;

[0189] The fourth switch module 22 is used to select whether to connect the first radio frequency transmission branch 20 to the third circulator 16 or to connect the second radio frequency transmission branch 21 to the third circulator 16.

[0190] Specifically, such as Figure 9 As shown, the switching assembly in this embodiment includes a fourth switching module 22. In this embodiment, the output ports of the first RF transmitting branch 20 and the second RF transmitting branch 21 are respectively connected to the third circulator 16 through the fourth switching module 22. Thus, during the uplink time slot in TDD mode, since the uplink frequency band is only used to transmit uplink received signals, the RF transceiver only outputs downlink transmitted signals. That is, the second transmit signal receiving link 18 only receives downlink transmitted signals. The fourth switching module 22 selects to connect the first RF transmitting branch 20 to the third circulator 16. At this time, the second RF transmitting branch 21 is open-circuited, and the third circulator 16 is used to connect the first RF transmitting branch 20 to the fourth filter 17 and connect the fourth filter 17 to the third RF receiving link 15. Thus, the uplink received signal passing through the fourth filter 17 will not mistakenly enter the first RF transmitting branch 20. The second RF transmitting branch 21 is connected to the third RF receiving link 15, while the downlink frequency band received signal transmitted through the first RF transmitting branch 20 will not mistakenly enter the third RF receiving link 15. In the downlink time slot of TDD mode, since the uplink frequency band is only used to transmit uplink frequency band transmission signals, the RF transceiver can simultaneously transmit downlink frequency band transmission signals and uplink frequency band transmission signals. That is, the second transmitting signal receiving link 18 simultaneously receives downlink frequency band transmission signals and uplink frequency band transmission signals. At this time, the fourth switch module 22 selects to connect the second RF transmitting branch 21 to the third circulator 16. At this time, the first RF transmitting branch 20 is disconnected, and the third circulator 16 is used to connect the second RF transmitting branch 21 to the fourth filter 17, so that the downlink frequency band transmission signal and uplink frequency band transmission signal transmitted through the second RF transmitting branch 21 will not mistakenly enter the third RF receiving link 15.

[0191] As a preferred embodiment, the fifth radio frequency transmission link 14 includes a second transmission signal receiving link 18, a first radio frequency transmission branch 20, and a second radio frequency transmission branch 21; the switching assembly includes a third switching module 19 and a fourth switching module 22;

[0192] The input port of the second transmit signal receiving link 18 is used to connect to the signal transmitting end of the RF transceiver and receive the downlink frequency band transmit signal and / or the uplink frequency band transmit signal; the output port of the second transmit signal receiving link 18 is connected to the first RF transmit branch 20 and the second RF transmit branch 21 respectively through the third switch module 19; the output ports of the first RF transmit branch 20 and the second RF transmit branch 21 are respectively connected to the third circulator 16 through the fourth switch module 22;

[0193] The first radio frequency transmission branch 20 is used to transmit the downlink frequency band transmission signal, and the second radio frequency transmission branch 21 is used to transmit the downlink frequency band transmission signal and the uplink frequency band transmission signal;

[0194] The third switch module 19 is used to select whether to connect the second transmit signal receiving link 18 to the first radio frequency transmit branch 20 or to connect the second transmit signal receiving link 18 to the second radio frequency transmit branch 21; the fourth switch module 22 is used to select whether to connect the first radio frequency transmit branch 20 to the third circulator 16 or to connect the second radio frequency transmit branch 21 to the third circulator 16.

[0195] Specifically, such as Figure 10As shown, the switching assembly in this embodiment includes both a third switching module 19 and a fourth switching module 22. Therefore, during the uplink time slot in TDD mode, since the uplink frequency band is only used to transmit uplink received signals, the RF transceiver only outputs downlink transmitted signals. That is, the second transmit signal receiving link 18 only receives downlink transmitted signals. The third switching module 19 then connects the second transmit signal receiving link 18 to the first RF transmit branch 20, and the fourth switching module 22 connects the first RF transmit branch 20 to the third circulator 16. At this time, the second RF transmit branch 21 is open-circuited, and the third circulator 16 connects the first RF transmit branch 20 to the fourth filter 17, and the fourth filter 17 connects to the third RF receive link 15. Thus, the uplink received signal passing through the fourth filter 17 will not mistakenly enter the first RF transmit branch 20 and the second RF transmit branch 21. The downlink received signal transmitted through the first RF transmit branch 20 will not mistakenly enter the third RF receive link 15. In the downlink time slot of TDD mode, since the uplink frequency band is only used to transmit uplink transmit signals, the RF transceiver can simultaneously transmit downlink and uplink transmit signals. That is, the second transmit signal receive link 18 simultaneously receives downlink and uplink transmit signals. The third switch module 19 selects to connect the second transmit signal receive link 18 to the second RF transmit branch 21, and the fourth switch module 22 selects to connect the second RF transmit branch 21 to the third circulator 16. At this time, the first RF transmit branch 20 is open, and the third circulator 16 is used to connect the second RF transmit branch 21 to the fourth filter 17. Thus, the downlink and uplink transmit signals transmitted through the second RF transmit branch 21 will not mistakenly enter the third RF receive link 15.

[0196] As a preferred embodiment, the third switch module 19 is specifically a third single-pole double-throw switch;

[0197] The active terminal of the third single-pole double-throw switch is connected to the output port of the second transmit signal receiving link 18, the first fixed terminal of the third single-pole double-throw switch is connected to the input port of the first radio frequency transmit branch 20, and the second fixed terminal of the third single-pole double-throw switch is connected to the input port of the second radio frequency transmit branch 21.

[0198] Specifically, such as Figure 11As shown, the third switch module 19 in this embodiment is specifically a third single-pole double-throw switch. It can be understood that in the uplink time slot of TDD mode, the active end of the third single-pole double-throw switch is connected to the first fixed end, so that the second transmit signal receiving link 18 is connected to the first radio frequency transmitting branch 20, thereby transmitting downlink frequency band transmit signals through the first radio frequency transmitting branch 20; while in the downlink time slot of TDD mode, the active end of the third single-pole double-throw switch is connected to the second fixed end, so that the second transmit signal receiving link 18 is connected to the second radio frequency transmitting branch 21, thereby transmitting downlink frequency band transmit signals and uplink frequency band transmit signals through the second radio frequency transmitting branch 21.

[0199] As a preferred embodiment, the fourth switch module 22 is specifically a fourth single-pole double-throw switch;

[0200] The movable end of the fourth single-pole double-throw switch is connected to the third circulator 16, the first fixed end of the fourth single-pole double-throw switch is connected to the output port of the first radio frequency transmission branch 20, and the second fixed end of the fourth single-pole double-throw switch is connected to the output port of the second radio frequency transmission branch 21.

[0201] Specifically, such as Figure 11 As shown, the fourth switch module 22 in this embodiment is specifically a fourth single-pole double-throw switch. It can be understood that in the uplink time slot of TDD mode, the first fixed terminal of the fourth single-pole double-throw switch is connected to the active terminal, so that the first radio frequency transmission branch 20 is connected to the third circulator 16, so as to transmit the downlink frequency band transmission signal to the fourth filter 17 through the third circulator 16; while in the downlink time slot of TDD mode, the second fixed terminal of the fourth single-pole double-throw switch is connected to the active terminal, so that the second radio frequency transmission branch 21 is connected to the third circulator 16, so as to transmit the downlink frequency band transmission signal and the uplink frequency band transmission signal to the fourth filter 17 through the third circulator 16.

[0202] As a preferred embodiment, the second transmit signal receive link 18 includes a fourth digital-to-analog converter 1801, a fifth filter 1802, an eighth power amplifier 1803, and a ninth power amplifier 1804.

[0203] The input port of the fourth digital-to-analog converter 1801 is used to connect to the signal transmitting end of the RF transceiver and receive the downlink frequency band transmission signal and / or the uplink frequency band transmission signal; the output port of the fourth digital-to-analog converter 1801 is connected to the input port of the fifth filter 1802, the output port of the fifth filter 1802 is connected to the input port of the eighth power amplifier 1803, the output port of the eighth power amplifier 1803 is connected to the input port of the ninth power amplifier 1804, and the output port of the ninth power amplifier 1804 is used to connect to the first RF transmitting branch 20 and the second RF transmitting branch 21 respectively.

[0204] Specifically, such as Figure 11As shown, the second transmit signal receiving link 18 in this embodiment further includes a fourth digital-to-analog converter 1801, a fifth filter 1802, an eighth power amplifier 1803, and a ninth power amplifier 1804. It is worth noting that since both the uplink and downlink signals emitted by the RF transceiver are digital signals, they need to be converted into analog signals to ensure smooth transmission of downlink service data. Therefore, the fourth digital-to-analog converter 1801 in this embodiment is used to convert the received uplink analog signal into an uplink digital signal to form an uplink transmit signal, and to convert the received downlink analog signal into a downlink digital signal to form a downlink transmit signal. Furthermore, the fifth filter 1802 acts as a bandpass filter, filtering the uplink transmit signal and / or downlink transmit signal from the fourth digital-to-analog converter 1801. The filtering process filters out signals within the uplink and downlink frequency bands, preventing interference signals from other frequency bands from passing through. This makes the signals entering the subsequent power amplifiers cleaner and prevents interference signals from being amplified during the amplification process, thus affecting communication quality. Furthermore, the eighth power amplifier 1803, as a preamplifier, performs preliminary amplification of the uplink and downlink transmitted signals, increasing their power to meet the input signal power requirements of the subsequent ninth power amplifier 1804, thus preparing for further amplification of the uplink and downlink transmitted signals. The amplification function of the eighth power amplifier 1803 enhances the driving capability of the uplink and downlink transmitted signals, enabling them to better resist transmission loss during subsequent transmission. Furthermore, the ninth power amplifier 1804, as the final stage amplifier, needs to amplify the uplink and downlink transmitted signals to a sufficient power level to meet transmission requirements and ensure that they can be effectively transmitted through the antenna. In this process, the ninth power amplifier 1804 needs to possess high power output capability and good linearity to guarantee the quality of the amplified signal and avoid distortion of the uplink and downlink transmitted signals.

[0205] Furthermore, compared to the RF front-end circuits provided in the first and second aspects, the RF front-end circuit in this embodiment only requires one filter, a preamplifier, and a final amplifier, further reducing the number of power amplifiers and saving hardware costs.

[0206] As a preferred embodiment, the first radio frequency transmission branch 20 is provided with a sixth filter 2001, which is used to filter out out-of-band spurious signals of the downlink frequency band transmission signal.

[0207] Specifically, this embodiment utilizes the filtering effect of the sixth filter 2001 to prevent out-of-band spurious signals (specifically, spurious signals falling into the uplink frequency band) from entering the third RF receiving link 15, thus avoiding interference from spurious signals to the RF transceiver.

[0208] As a preferred embodiment, the third radio frequency receiving link 15 includes a third radio frequency receiving signal processing module, a fifth switching module, and a seventh filter 1501;

[0209] The input port of the seventh filter 1501 is connected to the third circulator 16, the output port of the seventh filter 1501 is connected to one end of the fifth switch module, the other end of the fifth switch module is connected to the input port of the third radio frequency receiving signal processing module, and the output port of the third radio frequency receiving signal processing module is used to connect to the signal receiving end of the radio frequency transceiver.

[0210] The seventh filter 1501 is used to filter out out-of-band signals of the uplink frequency band received signals;

[0211] The fifth switch module is configured to control the on / off state of the third radio frequency receiving link 15.

[0212] Specifically, this embodiment utilizes the filtering effect of the seventh filter 1501 to suppress the out-of-band blocking signal strength of the downlink frequency band transmission signal that leaks to the third RF receiving link 15 through the third circulator 16, thereby avoiding blocking interference to the RF transceiver. Furthermore, the fifth switch module is configured to control the on / off state of the third RF receiving link 15. Understandably, during the uplink time slot in TDD mode, the fifth switch module controls the third RF receiving link 15 to be on, allowing the uplink frequency band received signal to be transmitted to the third RF receiving signal processing module. The third RF receiving signal processing module then processes the uplink frequency band received signal, enabling it to be received by the RF transceiver and processed further. During the downlink time slot in TDD mode, since the uplink frequency band is only used for RF signal transmission, the third RF receiving link 15 is not in operation. To prevent uplink and downlink transmission signals from mistakenly entering the third RF receiving link 15, the fifth switch module controls the third RF receiving link 15 to be off, diverting any potential transmission leakage signals to the grounded matching impedance, thus protecting the third RF receiving link 15 from interference.

[0213] As a preferred embodiment, the third radio frequency receiving signal processing module includes a third low noise amplifier 1504, a third gain module 1505, and a third analog-to-digital converter 1506.

[0214] The input port of the third low-noise amplifier 1504 is connected to the other end of the fifth switch module. The output port of the third low-noise amplifier 1504 is connected to the input port of the third gain module 1505. The output port of the third gain module 1505 is connected to the input port of the third analog-to-digital converter 1506. The output port of the third analog-to-digital converter 1506 is used to connect to the signal receiving end of the RF transceiver.

[0215] Specifically, such as Figure 11 As shown, the third RF receiving signal processing module in this embodiment further includes a third low-noise amplifier 1504, a third gain module 1505, and a third analog-to-digital converter 1506. It is worth noting that because the uplink received signal from the antenna experiences significant attenuation during transmission, resulting in a weak signal strength upon reaching the RF front-end circuit, the third low-noise amplifier 1504 is first used to amplify the uplink received signal, bringing it to a processable level. Furthermore, the third low-noise amplifier 1504 introduces very low noise during signal amplification, a crucial characteristic. Introducing excessive noise while amplifying the uplink received signal would degrade its quality, affecting subsequent demodulation and decoding, and ultimately reducing communication quality. The third low-noise amplifier 1504 ensures a high signal-to-noise ratio for the amplified uplink received signal, laying the foundation for accurate original signal reconstruction.

[0216] Furthermore, the third gain module 1505 can further adjust the gain of the uplink received signal after initial amplification by the third low-noise amplifier 1504. The third gain module 1505 can finely adjust the gain of the uplink received signal according to the actual needs of the circuit, ensuring that the strength of the uplink received signal reaches the input level range required by the subsequent third analog-to-digital converter 1506. Under different communication environments and signal strengths, the third gain module 1505 can flexibly adjust the gain to ensure the stability and reliability of the system. In addition, the uplink received signal will experience certain losses during transmission due to transmission lines, filters, and other components. The third gain module 1505 can compensate for these losses, ensuring that the uplink received signal maintains sufficient strength throughout the entire third RF receiving link 15, successfully completing the conversion from analog to digital signals and subsequent processing.

[0217] Furthermore, since the signal received by the RF transceiver is a digital signal, this embodiment needs to use a third analog-to-digital converter 1506 to convert the uplink frequency band received signal, which is an analog signal, into a digital signal, and then output it to the signal receiving end of the RF transceiver.

[0218] As a preferred embodiment, the fifth switch module includes a fifth single-pole double-throw switch 1502 and a third resistor 1503;

[0219] The movable terminal of the fifth single-pole double-throw switch 1502 is connected to the output port of the seventh filter 1501, the first fixed terminal of the fifth single-pole double-throw switch 1502 is connected to the input port of the third radio frequency receiving signal processing module, the second fixed terminal of the fifth single-pole double-throw switch 1502 is connected to one end of the third resistor 1503, and the other end of the third resistor 1503 is grounded.

[0220] Specifically, such as Figure 11 As shown, the fifth switch module in this embodiment further includes a fifth single-pole double-throw switch 1502 and a third resistor 1503. It can be understood that during the uplink time slot in TDD mode, the active terminal of the fifth single-pole double-throw switch 1502 is connected to the first fixed terminal, enabling the third RF receiving link 15 to conduct, thus allowing the uplink frequency band received signal to be transmitted to the third RF receiving signal processing module via the fifth single-pole double-throw switch 1502. During the downlink time slot in TDD mode, since the uplink frequency band is only used for RF signal transmission, the third RF receiving link 15 is not working. To prevent the uplink frequency band transmitted signal from mistakenly entering the third RF receiving link 15, the active terminal of the fifth single-pole double-throw switch 1502 is connected to the second fixed terminal, causing the third RF receiving link 15 to disconnect, guiding any potential transmission leakage signal to the grounded third resistor 1503, protecting the third RF receiving link 15 from interference.

[0221] As a preferred embodiment, the passband of the fourth filter 17 is an uplink frequency band and a downlink frequency band; wherein, the uplink frequency band is the frequency band in which the uplink transmitted signal and the uplink received signal are located, and the downlink frequency band is the frequency band in which the downlink transmitted signal is located.

[0222] The radio frequency front-end circuit provided in this embodiment of the present invention can transmit radio frequency signals using the downlink frequency band by utilizing the fifth radio frequency transmission link 14. Furthermore, through the fifth radio frequency transmission link 14 and the third radio frequency reception link 15, it can also adopt TDD duplex mode in the uplink frequency band. Thus, in the uplink time slot of TDD mode, it can receive radio frequency signals in the uplink frequency band and transmit radio frequency signals in the downlink frequency band. In the downlink time slot of TDD mode, it can simultaneously utilize the uplink and downlink frequency bands to transmit radio frequency signals, which significantly improves the utilization rate of uplink and downlink frequency band resources and avoids the phenomenon of insufficient downlink frequency band resources and idle uplink frequency band in FDD duplex mode.

[0223] Furthermore, by designing a fifth RF transmit link 14 for transmitting downlink and / or uplink transmit signals, the RF transceiver can be configured with only one signal transmitter, which can transmit both downlink and uplink transmit signals. This ensures that the number of signal transmit ports of the RF transceiver is equal to the number of signal receive ports, avoiding the problem of existing receive interfaces being idle or the need to customize RF transceiver chips.

[0224] Please see Figure 12 A fourth aspect of this utility model provides a radio frequency system, including a radio frequency transceiver 100, an antenna 300, and a radio frequency front-end circuit 200 as described in any embodiment of the first aspect; the radio frequency transceiver 100 has an uplink frequency band signal transmitting end, a downlink frequency band signal transmitting end, and an uplink frequency band signal receiving end; the downlink frequency band signal transmitting end is connected to the input port of a first radio frequency transmission link in the radio frequency front-end circuit 200, the uplink frequency band signal transmitting end is connected to the input port of a first TDD radio frequency transmission link in the radio frequency front-end circuit 200, and the uplink frequency band signal receiving end is connected to the output port of the first TDD radio frequency transmission link; the antenna 300 is connected to the first antenna port of a first duplexer in the radio frequency front-end circuit 200.

[0225] It is worth noting that in this embodiment, the input port of the first TDD radio frequency transmission link is the same as the input port of the second radio frequency transmission link, and the output port of the first TDD radio frequency transmission link is the same as the output port of the first radio frequency receiving link.

[0226] Please see Figure 12 The fifth aspect of this utility model provides a radio frequency system, including a radio frequency transceiver 100, an antenna 300, and a radio frequency front-end circuit 200 as described in any embodiment of the second aspect; the radio frequency transceiver 100 has a signal transmitting end and a signal receiving end; the signal transmitting end is connected to the input port of a first transmit signal receiving link in the radio frequency front-end circuit 200, and the signal receiving end is connected to the output port of a second TDD radio frequency transmission link in the radio frequency front-end circuit 200; the antenna 300 is connected to the second antenna port of a third duplexer in the radio frequency front-end circuit 200.

[0227] It is worth noting that in this embodiment, the output port of the second TDD radio frequency transmission link is the same as the output port of the second radio frequency receiving link.

[0228] Please see Figure 12The sixth aspect of this utility model provides a radio frequency system, including a radio frequency transceiver 100, an antenna 300, and a radio frequency front-end circuit 200 as described in any embodiment of the third aspect; the radio frequency transceiver 100 has a signal transmitting end and a signal receiving end; the signal transmitting end is connected to the input port of the fifth radio frequency transmitting link in the radio frequency front-end circuit 200, and the signal receiving end is connected to the output port of the third radio frequency receiving link in the radio frequency front-end circuit 200; the antenna 300 is connected to the other end of the fourth filter in the radio frequency front-end circuit 200.

[0229] A seventh aspect of this utility model provides a communication device, including a radio frequency system as described in any of the embodiments of the fourth to sixth aspects.

[0230] In addition to the radio frequency system described above, the communication device in this embodiment may also include a memory, a processor, and a computer program stored in the memory and capable of running on the processor.

[0231] For example, the computer program may be divided into one or more modules / units, which are stored in the memory and executed by the processor. The one or more modules / units may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program in the communication device.

[0232] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the communication device, connecting various parts of the communication device through various interfaces and lines.

[0233] The memory can be used to store the computer programs and / or modules. The processor implements various functions of the communication device by running or executing the computer programs and / or modules stored in the memory and by calling data stored in the memory. The memory may mainly include a program storage area and a data storage area. The program storage area may store the operating system, at least one application program required for a function (such as sound playback function, image playback function, etc.), etc.; the data storage area may store data created according to the use of the mobile phone (such as audio data, phonebook, etc.). In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as hard disk, memory, plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0234] The above description is the preferred embodiment of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this utility model, and these improvements and modifications are also considered to be within the protection scope of this utility model.

Claims

1. A radio frequency front-end circuit, characterized in that, It includes a first radio frequency transmission link, a first TDD radio frequency transmission link, and a first duplexer; The first duplexer has a first port, a second port, and a first antenna port for connecting an antenna; The first radio frequency transmission link is used to transmit downlink frequency band transmission signals, and the first radio frequency transmission link is connected to the first port; The first TDD radio frequency transmission link is used to transmit uplink frequency band transmit signals or uplink frequency band receive signals, and the first TDD radio frequency transmission link is connected to the second port.

2. The radio frequency front-end circuit as described in claim 1, characterized in that, The first TDD radio frequency transmission link includes a second radio frequency transmission link, a first radio frequency reception link, and a first circulator; The second radio frequency transmitting link is used to transmit the uplink frequency band transmitted signal, and the first radio frequency receiving link is used to transmit the uplink frequency band received signal. The output port of the second radio frequency transmitting link and the input port of the first radio frequency receiving link are connected to the second port through the first circulator. The first circulator is used to connect the second radio frequency transmitting link to the first duplexer and to the first radio frequency receiving link to the first duplexer.

3. The radio frequency front-end circuit as described in claim 1, characterized in that, The first radio frequency transmission link includes a first radio frequency transmission signal processing module and a first isolator; The input port of the first radio frequency transmission signal processing module is used to connect to the downlink frequency band signal transmission end of the radio frequency transceiver, the output port of the first radio frequency transmission signal processing module is connected to one end of the first isolator, and the other end of the first isolator is connected to the first port.

4. The radio frequency front-end circuit as described in claim 3, characterized in that, The first radio frequency transmission signal processing module includes a first digital-to-analog converter, a first filter, a first power amplifier, and a second power amplifier; The input port of the first digital-to-analog converter is used to connect to the downlink frequency band signal transmitting end of the radio frequency transceiver. The output port of the first digital-to-analog converter is connected to the input port of the first filter. The output port of the first filter is connected to the input port of the first power amplifier. The output port of the first power amplifier is connected to the input port of the second power amplifier. The output port of the second power amplifier is connected to one end of the first isolator.

5. The radio frequency front-end circuit as described in claim 2, characterized in that, The second radio frequency transmission link includes a second digital-to-analog converter, a second filter, a third power amplifier, and a fourth power amplifier; The input port of the second digital-to-analog converter is used to connect to the uplink signal transmitter of the RF transceiver. The output port of the second digital-to-analog converter is connected to the input port of the second filter. The output port of the second filter is connected to the input port of the third power amplifier. The output port of the third power amplifier is connected to the input port of the fourth power amplifier. The output port of the fourth power amplifier is connected to the first circulator.

6. The radio frequency front-end circuit as described in claim 2, characterized in that, The first radio frequency receiving link includes a first radio frequency receiving signal processing module and a first switching module; One end of the first switch module is connected to the first circulator, and the other end of the first switch module is connected to the input port of the first radio frequency receiving signal processing module. The output port of the first radio frequency receiving signal processing module is used to connect to the uplink frequency band signal receiving end of the radio frequency transceiver. The first switch module is configured to control the on / off state of the first radio frequency receiving link.

7. The radio frequency front-end circuit as described in claim 6, characterized in that, The first radio frequency receiving signal processing module includes a first low noise amplifier, a first gain module, and a first analog-to-digital converter; The input port of the first low-noise amplifier is connected to the other end of the first switching module, the output port of the first low-noise amplifier is connected to the input port of the first gain module, the output port of the first gain module is connected to the input port of the first analog-to-digital converter, and the output port of the first analog-to-digital converter is used to connect to the uplink signal receiving end of the RF transceiver.

8. The radio frequency front-end circuit as described in claim 6, characterized in that, The first switch module includes a first single-pole double-throw switch and a first resistor; The active terminal of the first single-pole double-throw switch is connected to the first circulator, the first fixed terminal of the first single-pole double-throw switch is connected to the input port of the first radio frequency receiving signal processing module, the second fixed terminal of the first single-pole double-throw switch is connected to one end of the first resistor, and the other end of the first resistor is grounded.

9. The radio frequency front-end circuit as described in claim 1 or 2, characterized in that, The first duplexer has a first filter chamber and a second filter chamber inside. The first port is connected to the first filter chamber, and the second port is connected to the second filter chamber. The first filter chamber and the second filter chamber are combined at the first antenna port. The filter in the first filter chamber is used to filter out out-of-band spurious signals of the downlink transmitted signal, and the filter in the second filter chamber is used to filter out out-of-band spurious signals of the uplink transmitted signal and the uplink received signal.

10. A radio frequency front-end circuit, characterized in that, It includes a first transmit signal receiving link, a third radio frequency transmit link, a second TDD radio frequency transmission link, a second duplexer, and a third duplexer; The input port of the first transmit signal receiving link is used to connect to the signal transmitting end of the radio frequency transceiver and to receive downlink frequency band transmit signals and / or uplink frequency band transmit signals; The output port of the first transmit signal receiving link is connected to the third radio frequency transmit link and the second TDD radio frequency transmission link respectively through the second duplexer; The third duplexer has a third port, a fourth port, and a second antenna port for connecting an antenna. The third radio frequency transmission link is used to transmit the downlink frequency band transmission signal, and the third radio frequency transmission link is connected to the third port; The second TDD radio frequency transmission link is used to transmit the uplink frequency band transmit signal or the uplink frequency band receive signal, and the second TDD radio frequency transmission link is connected to the fourth port.

11. The radio frequency front-end circuit as described in claim 10, characterized in that, The second TDD radio frequency transmission link includes a fourth radio frequency transmit link, a second radio frequency receive link, and a second circulator; The fourth radio frequency transmitting link is used to transmit the uplink frequency band transmitted signal, and the second radio frequency receiving link is used to transmit the uplink frequency band received signal. The input port of the fourth radio frequency transmitting link is connected to the output port of the first transmitted signal receiving link through the second duplexer. The output port of the fourth radio frequency transmitting link and the input port of the second radio frequency receiving link are connected to the fourth port through the second circulator. The second circulator is used to connect the fourth radio frequency transmitting link to the third duplexer and to the second radio frequency receiving link to the third duplexer.

12. The radio frequency front-end circuit as described in claim 11, characterized in that, The first transmit signal receive link includes a third digital-to-analog converter, a third filter, and a fifth power amplifier; The input port of the third digital-to-analog converter is used to connect to the signal transmitting end of the RF transceiver and receive the downlink frequency band transmission signal and the uplink frequency band transmission signal; the output port of the third digital-to-analog converter is connected to the input port of the third filter, the output port of the third filter is connected to the input port of the fifth power amplifier, and the output port of the fifth power amplifier is connected to the third RF transmission link and the fourth RF transmission link respectively through the second duplexer.

13. The radio frequency front-end circuit as described in claim 12, characterized in that, The third radio frequency transmission link includes a sixth power amplifier and a second isolator; The input port of the sixth power amplifier is connected to the output port of the fifth power amplifier through the second duplexer, the output port of the sixth power amplifier is connected to one end of the second isolator, and the other end of the second isolator is connected to the third port.

14. The radio frequency front-end circuit as described in claim 12, characterized in that, The fourth radio frequency transmission link includes a seventh power amplifier; The input port of the seventh power amplifier is connected to the output port of the fifth power amplifier through the second duplexer, and the output port of the seventh power amplifier is connected to the second circulator.

15. The radio frequency front-end circuit as described in claim 11, characterized in that, The second radio frequency receiving link includes a second radio frequency receiving signal processing module and a second switching module; One end of the second switch module is connected to the second circulator, and the other end of the second switch module is connected to the input port of the second radio frequency receiving signal processing module. The output port of the second radio frequency receiving signal processing module is used to connect to the signal receiving end of the radio frequency transceiver. The second switch module is configured to control the on / off state of the second radio frequency receiving link.

16. The radio frequency front-end circuit as described in claim 15, characterized in that, The second radio frequency receiving signal processing module includes a second low-noise amplifier, a second gain module, and a second analog-to-digital converter; The input port of the second low-noise amplifier is connected to the other end of the second switching module, the output port of the second low-noise amplifier is connected to the input port of the second gain module, the output port of the second gain module is connected to the input port of the second analog-to-digital converter, and the output port of the second analog-to-digital converter is used to connect to the signal receiving end of the RF transceiver.

17. The radio frequency front-end circuit as described in claim 15, characterized in that, The second switching module includes a second single-pole double-throw switch and a second resistor; The active terminal of the second single-pole double-throw switch is connected to the second circulator, the first fixed terminal of the second single-pole double-throw switch is connected to the input port of the second radio frequency receiving signal processing module, the second fixed terminal of the second single-pole double-throw switch is connected to one end of the second resistor, and the other end of the second resistor is grounded.

18. The radio frequency front-end circuit as described in claim 11, characterized in that, The second duplexer has a transmit signal input port, a downlink frequency band signal output port, and an uplink frequency band signal output port; the output port of the first transmit signal receiving link is connected to the transmit signal input port, the input port of the third radio frequency transmit link is connected to the downlink frequency band signal output port, and the input port of the fourth radio frequency transmit link is connected to the uplink frequency band signal output port.

19. The radio frequency front-end circuit as described in claim 18, characterized in that, The second duplexer has a third filter chamber and a fourth filter chamber inside. The downlink frequency band signal output port is connected to the third filter chamber, and the uplink frequency band signal output port is connected to the fourth filter chamber. The third filter chamber and the fourth filter chamber are combined at the transmit signal input port. The filter in the third filter chamber is used to filter out out-of-band spurious signals of the downlink frequency band transmit signal, and the filter in the fourth filter chamber is used to filter out out-of-band spurious signals of the uplink frequency band transmit signal.

20. The radio frequency front-end circuit as described in claim 10 or 11, characterized in that, The third duplexer contains a fifth filter chamber and a sixth filter chamber. The third port is connected to the fifth filter chamber, and the fourth port is connected to the sixth filter chamber. The fifth and sixth filter chambers are combined at the second antenna port. The filter in the fifth filter chamber is used to filter out out-of-band spurious signals of the downlink transmitted signal, and the filter in the sixth filter chamber is used to filter out out-of-band spurious signals of the uplink transmitted signal and the uplink received signal.

21. A radio frequency front-end circuit, characterized in that, It includes a fifth radio frequency transmit link, a third radio frequency receive link, a switching assembly, a third circulator, and a fourth filter; The input port of the fifth RF transmit link is used to connect to the signal transmitting end of the RF transceiver and to receive downlink frequency band transmit signals and / or uplink frequency band transmit signals; the third RF receive link is used to transmit uplink frequency band receive signals; the output port of the fifth RF transmit link and the input port of the third RF receive link are connected to one end of the fourth filter through the third circulator, and the other end of the fourth filter is used to connect to the antenna; The third circulator is used to connect the fifth radio frequency transmit link to the fourth filter, and to connect the third radio frequency receive link to the fourth filter; The switching component is disposed in the fifth radio frequency transmission link. The switching component is used to select whether to send the downlink frequency band transmission signal and the uplink frequency band transmission signal to the fourth filter, or to send the downlink frequency band transmission signal to the fourth filter.

22. The radio frequency front-end circuit as described in claim 21, characterized in that, The fifth radio frequency transmission link includes a second transmission signal receiving link, a first radio frequency transmission branch, and a second radio frequency transmission branch; the switching assembly includes a third switching module; The input port of the second transmit signal receiving link is used to connect to the signal transmitting end of the radio frequency transceiver and to receive the downlink frequency band transmit signal and / or the uplink frequency band transmit signal; The output port of the second transmit signal receive link is connected to the first RF transmit branch and the second RF transmit branch respectively through the third switch module; the output ports of the first RF transmit branch and the second RF transmit branch are both connected to the third circulator; The first radio frequency transmission branch is used to transmit the downlink frequency band transmission signal, and the second radio frequency transmission branch is used to transmit the downlink frequency band transmission signal and the uplink frequency band transmission signal; The third switch module is used to select whether to connect the second transmit signal receiving link to the first radio frequency transmit branch, or to connect the second transmit signal receiving link to the second radio frequency transmit branch.

23. The radio frequency front-end circuit as described in claim 21, characterized in that, The fifth radio frequency transmission link includes a second transmission signal receiving link, a first radio frequency transmission branch, and a second radio frequency transmission branch; the switching assembly includes a fourth switching module; The input port of the second transmit signal receiving link is used to connect to the signal transmitting end of the radio frequency transceiver and to receive the downlink frequency band transmit signal and / or the uplink frequency band transmit signal; The output port of the second transmit signal receive link is connected to the first RF transmit branch and the second RF transmit branch respectively; the output ports of the first RF transmit branch and the second RF transmit branch are respectively connected to the third circulator through the fourth switch module; The first radio frequency transmission branch is used to transmit the downlink frequency band transmission signal, and the second radio frequency transmission branch is used to transmit the downlink frequency band transmission signal and the uplink frequency band transmission signal; The fourth switch module is used to select whether to connect the first radio frequency transmission branch to the third circulator or the second radio frequency transmission branch to the third circulator.

24. The radio frequency front-end circuit as described in claim 21, characterized in that, The fifth radio frequency transmission link includes a second transmission signal receiving link, a first radio frequency transmission branch, and a second radio frequency transmission branch; the switching assembly includes a third switching module and a fourth switching module; The input port of the second transmit signal receiving link is used to connect to the signal transmitting end of the radio frequency transceiver and to receive the downlink frequency band transmit signal and / or the uplink frequency band transmit signal; The output port of the second transmit signal receive link is connected to the first RF transmit branch and the second RF transmit branch respectively through the third switch module; the output ports of the first RF transmit branch and the second RF transmit branch are connected to the third circulator respectively through the fourth switch module. The first radio frequency transmission branch is used to transmit the downlink frequency band transmission signal, and the second radio frequency transmission branch is used to transmit the downlink frequency band transmission signal and the uplink frequency band transmission signal; The third switch module is used to select whether to connect the second transmit signal receiving link to the first radio frequency transmit branch or to the second transmit signal receiving link; the fourth switch module is used to select whether to connect the first radio frequency transmit branch to the third circulator or to the second radio frequency transmit branch.

25. The radio frequency front-end circuit as described in claim 22 or 24, characterized in that, The third switch module is specifically a third single-pole double-throw switch; The movable terminal of the third single-pole double-throw switch is connected to the output port of the second transmit signal receiving link, the first fixed terminal of the third single-pole double-throw switch is connected to the input port of the first radio frequency transmit branch, and the second fixed terminal of the third single-pole double-throw switch is connected to the input port of the second radio frequency transmit branch.

26. The radio frequency front-end circuit as described in claim 23 or 24, characterized in that, The fourth switch module is specifically a fourth single-pole double-throw switch; The movable terminal of the fourth single-pole double-throw switch is connected to the third circulator, the first fixed terminal of the fourth single-pole double-throw switch is connected to the output port of the first radio frequency transmission branch, and the second fixed terminal of the fourth single-pole double-throw switch is connected to the output port of the second radio frequency transmission branch.

27. The radio frequency front-end circuit according to any one of claims 22 to 24, characterized in that, The second transmit signal receive link includes a fourth digital-to-analog converter, a fifth filter, an eighth power amplifier, and a ninth power amplifier; The input port of the fourth digital-to-analog converter is used to connect to the signal transmitting end of the RF transceiver and receive the downlink frequency band transmission signal and / or the uplink frequency band transmission signal; the output port of the fourth digital-to-analog converter is connected to the input port of the fifth filter, the output port of the fifth filter is connected to the input port of the eighth power amplifier, the output port of the eighth power amplifier is connected to the input port of the ninth power amplifier, and the output port of the ninth power amplifier is used to connect to the first RF transmission branch and the second RF transmission branch respectively.

28. The radio frequency front-end circuit as described in any one of claims 22 to 24, characterized in that, The first radio frequency transmission branch is provided with a sixth filter, which is used to filter out out-of-band spurious signals of the downlink frequency band transmission signal.

29. The radio frequency front-end circuit as described in claim 21, characterized in that, The third radio frequency receiving link includes a third radio frequency receiving signal processing module, a fifth switching module, and a seventh filter; The input port of the seventh filter is connected to the third circulator, the output port of the seventh filter is connected to one end of the fifth switch module, the other end of the fifth switch module is connected to the input port of the third radio frequency receiving signal processing module, and the output port of the third radio frequency receiving signal processing module is used to connect to the signal receiving end of the radio frequency transceiver. The seventh filter is used to filter out out-of-band signals of the uplink frequency band received signals; The fifth switch module is configured to control the on / off state of the third radio frequency receiving link.

30. The radio frequency front-end circuit as described in claim 29, characterized in that, The third radio frequency receiving signal processing module includes a third low-noise amplifier, a third gain module, and a third analog-to-digital converter. The input port of the third low-noise amplifier is connected to the other end of the fifth switch module, the output port of the third low-noise amplifier is connected to the input port of the third gain module, the output port of the third gain module is connected to the input port of the third analog-to-digital converter, and the output port of the third analog-to-digital converter is used to connect to the signal receiving end of the RF transceiver.

31. The radio frequency front-end circuit as described in claim 29, characterized in that, The fifth switch module includes a fifth single-pole double-throw switch and a third resistor; The active terminal of the fifth single-pole double-throw switch is connected to the output port of the seventh filter, the first fixed terminal of the fifth single-pole double-throw switch is connected to the input port of the third radio frequency receiving signal processing module, the second fixed terminal of the fifth single-pole double-throw switch is connected to one end of the third resistor, and the other end of the third resistor is grounded.

32. The radio frequency front-end circuit as described in claim 21, characterized in that, The passband of the fourth filter is an uplink frequency band and a downlink frequency band; wherein, the uplink frequency band is the frequency band in which the uplink transmitted signal and the uplink received signal are located, and the downlink frequency band is the frequency band in which the downlink transmitted signal is located.

33. A radio frequency system, characterized in that, The device includes a radio frequency transceiver, an antenna, and a radio frequency front-end circuit as described in any one of claims 1 to 9; the radio frequency transceiver has an uplink frequency band signal transmitter, a downlink frequency band signal transmitter, and an uplink frequency band signal receiver; the downlink frequency band signal transmitter is connected to the input port of a first radio frequency transmission link in the radio frequency front-end circuit, the uplink frequency band signal transmitter is connected to the input port of a first TDD radio frequency transmission link in the radio frequency front-end circuit, and the uplink frequency band signal receiver is connected to the output port of the first TDD radio frequency transmission link; the antenna is connected to the first antenna port of a first duplexer in the radio frequency front-end circuit.

34. A radio frequency system, characterized in that, The device includes a radio frequency transceiver, an antenna, and a radio frequency front-end circuit as described in any one of claims 10 to 20; the radio frequency transceiver has a signal transmitting end and a signal receiving end; the signal transmitting end is connected to the input port of a first transmit signal receiving link in the radio frequency front-end circuit, and the signal receiving end is connected to the output port of a second TDD radio frequency transmission link in the radio frequency front-end circuit; the antenna is connected to the second antenna port of a third duplexer in the radio frequency front-end circuit.

35. A radio frequency system, characterized in that, The device includes a radio frequency transceiver, an antenna, and a radio frequency front-end circuit as described in any one of claims 21 to 32; the radio frequency transceiver has a signal transmitting end and a signal receiving end; the signal transmitting end is connected to the input port of a fifth radio frequency transmitting link in the radio frequency front-end circuit, and the signal receiving end is connected to the output port of a third radio frequency receiving link in the radio frequency front-end circuit; the antenna is connected to the other end of a fourth filter in the radio frequency front-end circuit.

36. A communication device, characterized in that, Including the radio frequency system as described in any one of claims 33 to 35.

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