Test circuit

Abstract

The utility model discloses a test circuit, which relates to the technical field of communication, and comprises an antenna port for accessing an antenna, a radio frequency transceiver, a change-over switch circuit and a filter circuit, the change-over switch circuit is electrically connected with the radio frequency transceiver and the filter circuit, and the filter circuit is electrically connected with the antenna port. The change-over switch circuit is used for switching and outputting a transmitting signal to the filter circuit when interference exists between a receiving signal and the transmitting signal of the radio frequency transceiver; and the filter circuit is electrically connected with the change-over switch circuit and the antenna port, and the filter circuit is used for filtering the transmitting signal and outputting the filtered transmitting signal to the antenna port. The utility model aims to optimize the sensitivity index of the SCC, ensure the throughput and networking quality of the CA combined signal in actual use, and further improve the user experience.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a test circuit. Background Art

[0002] Band-edge CA (band edge carrier aggregation) refers to an intra-band non-continuous CA scenario, where the TX (transmit signal) of the PCC (primary carrier component) is in the high channel and the RX (receive signal) of the SCC (secondary carrier component) is in the low channel. Since the spacing between the operating frequency bands of the transmit (TX) signal and the receive (RX) signal is only 20 MHz in some frequency bands, such as the TX frequency band of B2 is 1850-1910 MHz, and the RX frequency band is 1930-1990 MHz; it is difficult for the TX or RX filter to suppress the receive frequency band (RX band) or the transmit frequency band (TX band). As a result, when conducting relevant tests in the Band-edge CA working mode, the sensitivity of the SCC will be affected by the noise of the PCC TX falling on the RX, thereby affecting the throughput and data transmission speed of this scenario and reducing the user experience. Utility Model Content

[0003] The main purpose of the utility model is to provide a test circuit, which aims to optimize the sensitivity index of SCC, ensure the throughput and networking quality of CA combination signal in actual use, and thus improve the user experience.

[0004] To achieve the above object, the utility model provides a test circuit, the test circuit comprising an antenna port for accessing an antenna and a radio frequency transceiver, and further comprising:

[0005] A switching circuit, the switching circuit electrically connecting the radio frequency transceiver and the filter circuit, the switching circuit being used for switching the transmission signal to be output to the filter circuit when there is interference between the reception signal and the transmission signal of the radio frequency transceiver;

[0006] A filter circuit is electrically connected to the switching circuit and the antenna port, and is used for filtering the transmission signal and then outputting it to the antenna port.

[0007] In one embodiment, the switching switch circuit includes a first switching switch and a second switching switch, the first switching switch electrically connects the RF transceiver and the filtering circuit, and the second switching switch electrically connects the filtering circuit and the antenna port.

[0008] In one embodiment, the fixed end of the first switch is electrically connected to the output end of the RF transceiver, the active end of the first switch includes a first contact and a second contact, the first contact is electrically connected to the filter circuit, the fixed end of the second switch is electrically connected to the antenna port, the active end of the second switch includes a third contact and a fourth contact, the third contact is electrically connected to the filter circuit, and the fourth contact is electrically connected to the second contact of the first switch.

[0009] In one embodiment, the controlled end of the first switch is electrically connected to the control end of the RF transceiver, and the controlled end of the second switch is electrically connected to the control end of the RF transceiver, so that the RF transceiver controls the switching logic of the first switch and the second switch based on the working state.

[0010] In one embodiment, the test circuit further includes:

[0011] A power amplifier circuit, wherein an input end of the power amplifier circuit is electrically connected to an output end of the radio frequency transceiver, and an output end of the power amplifier circuit is electrically connected to a fixed end of the switching circuit;

[0012] The power amplifier circuit is used to amplify the transmission signal output by the radio frequency transceiver.

[0013] In one embodiment, the test circuit further includes:

[0014] An isolation circuit is electrically connected to the filter circuit and the antenna port, and is used to isolate the transmit signal and the receive signal of the radio frequency transceiver.

[0015] In one embodiment, the isolation circuit includes a duplexer, the fixed end of the second switch is electrically connected to a transmitting port of the duplexer, and the output end of the duplexer is electrically connected to the antenna port.

[0016] In one embodiment, the filtering circuit comprises a notch filter, an input end of the notch filter is electrically connected to a first contact of the first switch, and an output end of the notch filter is electrically connected to a third contact of the second switch.

[0017] The utility model proposes a test circuit, which includes an antenna port for accessing an antenna and a radio frequency transceiver, and also includes a filtering circuit and a switching switch circuit, wherein the switching switch circuit is electrically connected to the radio frequency transceiver and the filtering circuit, and the switching switch circuit is used to switch the transmission signal to the filtering circuit when interference exists between the reception signal and the transmission signal of the radio frequency transceiver; and a filtering circuit, wherein the filtering circuit is electrically connected to the switching switch circuit and the antenna port, and the filtering circuit is used to output the transmission signal to the antenna port after filtering.

[0018] In practical applications, when there is a CA combination signal, if there is interference between the received signal and the transmitted signal emitted by the RF transceiver, the transmitted signal can be output to the filter circuit by switching the path between the fixed end and the first contact of the switch circuit, so that the filter circuit outputs the transmitted signal to the antenna port after filtering. The utility model utilizes the characteristics that the filter circuit only has a strong suppressive effect on the noise within the target frequency range, but has little effect on signals of other frequencies, and effectively reduces the noise of the transmitted signal falling on the received signal. In this way, it is possible to prevent noise of a specific frequency in the transmitted signal emitted by the RF transceiver from entering the path of the received signal, optimize the sensitivity index of the SCC, and ensure the throughput and networking quality of the CA combination signal in actual use, thereby improving the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0020] Figure 1 A schematic diagram of a circuit module of an embodiment of a test circuit of the utility model;

[0021] Figure 2 A schematic diagram of a circuit module of another embodiment of the test circuit of the utility model;

[0022] Figure 3 A schematic diagram of a circuit module of another embodiment of the test circuit of the utility model;

[0023] Figure 4 A schematic diagram of a circuit module of another embodiment of the test circuit of the utility model;

[0024] Figure 5 A schematic diagram of a circuit module of another embodiment of the test circuit of the utility model;

[0025] Figure 6 This is a schematic diagram of a circuit module of another embodiment of the test circuit of the utility model.

[0026] Description of Figure Numbers:

[0027] 10. Antenna port; 20. RF transceiver; 30. Filter circuit; 40. Switching circuit; 41. First switching switch; 42. Second switching switch; 50. Power amplifier circuit; 60. Isolation circuit.

[0028] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0030] In addition, in the present utility model, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0031] It is understandable that CA usually refers to carrier aggregation technology. Carrier aggregation is a key technology used in mobile communication systems such as LTE-Advanced and 5G to increase effective bandwidth and improve data transmission rate. It allows devices to aggregate multiple carriers on one or more continuous or non-continuous frequency bands at the same time to obtain greater throughput.

[0032] Band-edge CA refers to an intra-band non-continuous CA scenario, where the TX of the PCC (primary carrier component) is in a high channel and the RX of the SCC (sencondary carrier component) is in a low channel. Since the distance between the working frequency bands of the transmit (TX) signal and the receive (RX) signal is only 20 MHz in some frequency bands, such as the TX frequency band of B2 is 1850-1910 MHz and the RX frequency band is 1930-1990 MHz; it is difficult for the TX or RX filter to suppress the receive frequency band (RX band) or the transmit frequency band (TX band). As a result, when conducting relevant tests in the band edge carrier aggregation (band-edge CA) working mode, the sensitivity of the SCC will be affected by the noise of the PCC TX falling on the RX, thereby affecting the throughput and data transmission speed of this scenario and reducing the user experience.

[0033] For this purpose, refer to Figure 1 The utility model proposes a test circuit, the test circuit includes an antenna port 10 for accessing an antenna and a radio frequency transceiver 20, and also includes:

[0034] A switching circuit 40, wherein the switching circuit 40 is electrically connected to the RF transceiver 20 and the filter circuit 30, and the switching circuit 40 is used to switch the transmit signal to the filter circuit 30 when there is interference between the receive signal and the transmit signal of the RF transceiver 20;

[0035] The filter circuit 30 is electrically connected to the switch circuit 40 and the antenna port 10 , and is used for filtering the transmission signal and then outputting it to the antenna port 10 .

[0036] In the present embodiment, the filter circuit 30 can be implemented by filtering devices such as a low-pass filter (LPF-Low Pass Filter), a high-pass filter (HPF-High Pass Filter), a band-pass filter (BPF-Band Pass Filter), and a notch filter. The switching circuit 40 can be implemented by switching tubes such as a PIN diode switch and a field effect transistor, or switching devices such as a relay and a contactor, or a radio frequency switch SPDT. In the present embodiment, the switching circuit 40 is implemented by using a radio frequency switch. Among them, the switching circuit 40 includes any one of an SP2T radio frequency switch, an SP4T radio frequency switch, and an SP6T radio frequency switch. The corresponding radio frequency switch can be set according to the number of frequency bands actually required.

[0037] It should be noted that Single Band testing generally refers to testing for a single frequency band in the field of wireless communications. This test is mainly used to verify the performance indicators of wireless devices (such as mobile phones, routers, base stations, etc.) in a specified single frequency band to ensure that they can work normally in this frequency band and comply with relevant industry standards, such as those formulated by 3GPP, IEEE, ETSI, etc. Therefore, when the transmission power of the CA combined signal meets the allowable deviation range of the 3GPP rated carrier output power, the SPDT1 RF switch can be directly added to the signal path of the Single Band test as a switching switch circuit 40, wherein the input end of the SPDT1 RF switch is the fixed end of the switching switch circuit 40, which is used to be electrically connected to the output end of the RF transceiver 20, the first output end of the SPDT1 RF switch is the second contact of the switching switch circuit 40, which is used to be directly electrically connected to the antenna port 10, and the second output end of the SPDT1 RF switch is the first contact of the switching switch circuit 40, which is used to be electrically connected to the output end of the filter circuit 30. In this way, during the Single Band test, the control circuit inside the RF transceiver 20 controls the SPDT1 RF switch to turn on the path between its own input end and the first output end based on the preset switching logic, so that the transmission signal can be output by the RF transceiver 20 and then directly reach the antenna port 10 through the SPDT1 RF switch; under the band-edge CA test, the control circuit inside the RF transceiver 20 controls the SPDT1 RF switch to turn on the path between its own input end and the second output end, so that the transmission signal is output from the RF transceiver 20 through the SPDT1 RF switch to the filter circuit 30, and is output to the antenna port 10 after being filtered by the filter circuit 30.

[0038] Through the above settings, adding a switching circuit 40 and a filtering circuit 30 in the transmission path of the Single Band test can suppress the noise of the transmission signal falling on the receiving signal, the circuit is simple, and the design cost is reduced. At the same time, the transmission signal can still go through the original path during the Single Band test, ensuring the TX performance of the single band test.

[0039] It is understandable that since the notch filter is used to suppress a very narrow frequency band, that is, only a specific interference frequency is deeply attenuated. Compared with other filters, it can more accurately target the frequency of the transmitted signal or its harmonics, avoiding unnecessary loss of signals in non-interference frequency bands, thereby maintaining the integrity of the received signal. In addition, the notch filter can effectively reduce the leakage of the transmitted signal at the edge of its frequency band (out-of-band emission), which is crucial for protecting the received signal of the adjacent channel from interference. Therefore, in this embodiment, the filtering circuit 30 includes a notch filter.

[0040] The notch filter may be an analog notch filter, such as a double-T notch filter, an LC notch filter, etc.; or a digital notch filter, such as an IIR notch filter, a FIR notch filter, etc. It is understood that the antenna port 10 is used to provide a channel for transmitting or receiving signals.

[0041] Specifically, when there is a CA combined signal, if the frequency interval between the transmit signal (TX) of the main carrier (PCC) and the receive signal (RX) of the secondary carrier (SCC) is very small, the energy of the transmit signal of the PCC near the edge of its frequency band may not be completely suppressed, and this part of the energy will leak into the receive frequency band of the SCC, causing interference. At this time, the switching circuit 40 will conduct the path between the filter circuit 30 and the output end of the RF transceiver 20, and output the transmit signal output by the RF transceiver 20 to the filter circuit 30 through the first contact, so that the filter circuit 30 outputs the transmit signal to the antenna port 10 after filtering. In this way, the filter circuit 30 increases the suppression effect of the transmit signal falling on the receive signal, thereby improving the SCC sensitivity. At the same time, if there is no interference between the received signal and the transmitted signal emitted by the RF transceiver 20, for example, the frequency interval between the transmit signal (TX) of the main carrier (PCC) and the receive signal (RX) of the auxiliary carrier (SCC) is large, the transmit signal will not affect the receive signal, and the switching circuit 40 outputs the transmit signal directly to the antenna port 10 via the second contact.

[0042] It should be noted that if a notch filter is used as the filter circuit 30, due to the setting of the notch filter, the suppression of the transmitted signal will be increased, the difference in the working frequency band of the transmitted signal will be increased, and the transmission power will be reduced. However, when implementing carrier aggregation, for each aggregated carrier, its output power should be maintained within a certain range of the rated carrier output power (Prated) declared by the manufacturer. Under the 3GPP standard, the power threshold (threshold) only needs to meet the allowable deviation range of the "+2dB" power gain and the allowable deviation range of the "-3dB" power loss. Among them, "+2dB" means that the output power shall not exceed its rated carrier output power plus 2dB; "-3dB" means that the output power should not be lower than its rated carrier output power minus 3dB. Therefore, due to the relaxation of the 3GPP power threshold, the setting of the notch filter will not have a significant impact on the transmission power.

[0043] In practical applications, when there is a CA combined signal, if there is interference between the received signal and the transmitted signal transmitted by the RF transceiver 20, the transmitted signal can be output to the filter circuit 30 by switching the path between the fixed end and the first contact of the switch circuit 40, so that the filter circuit 30 outputs the transmitted signal to the antenna port 10 after filtering. The utility model utilizes the characteristics that the filter circuit 30 only has a strong suppressive effect on the noise within the target frequency range, and has little effect on signals of other frequencies, and effectively reduces the noise of the transmitted signal falling on the received signal. In this way, it is possible to prevent the noise of a specific frequency in the transmitted signal transmitted by the RF transceiver 20 from entering the path of the received signal, optimize the sensitivity index of the SCC, and ensure the throughput and networking quality of the CA combined signal in actual use, thereby improving the user experience.

[0044] It is understandable that effective long-distance transmission is crucial in wireless communication environments. Since the energy radiated by an antenna is proportional to the square of the current on it, there must be sufficient power to ensure that the signal can reach the receiving end under various propagation conditions while overcoming the energy attenuation caused by factors such as distance, path loss, and multipath fading during transmission.

[0045] For this purpose, refer to Figure 3 , the test circuit comprises:

[0046] A power amplifier circuit 50, wherein an input end of the power amplifier circuit 50 is electrically connected to an output end of the RF transceiver 20, and an output end of the power amplifier circuit 50 is electrically connected to a fixed end of the switching circuit 40;

[0047] The power amplifier circuit 50 is used to amplify the transmission signal output by the RF transceiver 20 .

[0048] In this embodiment, the power amplifier circuit 50 can be implemented by a power amplifier such as a class A amplifier, a class B amplifier, or a class AB amplifier. Alternatively, it can be implemented by a power amplifier chip, such as a CB2401 RF front-end chip, an RFX2411 power amplifier chip, an 8TR8201 RF transceiver circuit, etc. It should be noted that the power amplifier chip in this embodiment not only has a power amplification function, but also integrates the transmission and reception functions.

[0049] Specifically, the power amplifier circuit 50 can amplify the low-power transmission signal output by the RF transceiver 20 and convert it into a high-power signal to the antenna port 10. Whether in single-band testing or CA testing, the power amplifier circuit 50 can amplify the transmission signal output by the RF transceiver 20 and output it. For example, in combination with the above-mentioned embodiment, the output end of the power amplifier circuit 50 can be electrically connected to the fixed end of the switching circuit 40, so that in single-band testing, the power amplifier circuit 50 amplifies the transmission signal output by the RF transceiver 20 and outputs it to the antenna port 10 through the second contact of the switching circuit 40; similarly, in CA testing, the power amplifier circuit 50 amplifies the transmission signal output by the RF transceiver 20 and outputs it to the notch filter through the first contact of the switching circuit 40, so that the notch filter filters it and outputs it to the antenna port 10.

[0050] The power amplifier circuit 50 can amplify the transmission signal (transmission signal) output by the RF transceiver 20, making the signal quality of the communication system more reliable at a preset distance. In this way, the transmission capacity of the transmission signal is enhanced, and the performance and reliability of the entire communication system are improved.

[0051] It is understandable that in order to ensure that the devices in the communication network can effectively distinguish and process the transmitted and received signals, so as to achieve efficient and stable two-way communication. Figure 4 , the test circuit further includes:

[0052] The isolation circuit 60 is electrically connected to the filter circuit 30 and the antenna port 10 , and is used to isolate the transmission signal and the reception signal of the radio frequency transceiver 20 .

[0053] The RF transceiver 20 includes a transmitting end and a receiving end, and the transmitting end is electrically connected to the fixed end of the switching circuit 40. The isolation circuit 60 includes a first isolation circuit and a second isolation circuit, the first isolation circuit has a first input port and a first output port, and the second isolation circuit has a second input port and a second output port;

[0054] The first input port is electrically connected to the output end of the filter circuit 30, and is used to receive the transmission signal output by the filter circuit 30; the first output port is electrically connected to the antenna port 10, and is used to transmit the transmission signal to the antenna port 10; the second input port is electrically connected to the antenna port 10, and is used to receive the reception signal; the second output port is electrically connected to the receiving end of the RF transceiver 20, and is used to output the reception signal to the RF transceiver 20;

[0055] The first isolation circuit and the second isolation circuit are respectively configured to allow signals within a preset frequency range to pass through, so as to isolate the transmission signal and the reception signal and then output them.

[0056] In this embodiment, the isolation circuit 60 can be implemented by a low-frequency isolation circuit 60, an intermediate-frequency isolation circuit 60, a high-frequency isolation circuit 60, etc. It can be understood that since the duplexer has the performance of frequency selectivity, high isolation, etc., in this embodiment, the isolation circuit 60 includes a duplexer. In addition, compared with using two independent filters to achieve isolation of the transmit and receive signals, the duplexer as an integrated device can reduce the required space and cost and simplify the system design.

[0057] It should be noted that the first isolation circuit is located on the transmission signal path, and its purpose is to ensure that the transmission signal is as pure as possible and will not be fed back to the receiving path to cause interference during the process of the transmission signal being output from the filter circuit 30 to the antenna port 10. The transmission signal is first processed by the filter circuit 30 and output to the first input port of the first isolation circuit. The first isolation circuit only allows signals within the preset transmission frequency range to pass through, effectively preventing signals of other frequencies from entering, and ensuring the directional transmission of the signal. The transmission signal is then output from the first output port of the first isolation circuit to the antenna port 10 and transmitted through the antenna port 10. The second isolation circuit is located on the receiving signal path, responsible for receiving external signals (received signals) from the antenna and transmitting them to the receiving end of the RF transceiver 20, while preventing leakage or reflection of the transmission signal from causing interference to the receiving signal. When signals arrive at the antenna port 10 from the outside, these signals (including the expected received signals) enter through the second input port of the second isolation circuit. The second isolation circuit only allows signals within a preset receiving frequency range to pass through, and filters out unnecessary signals, including signals that may have leaked from the transmitting end. The isolated received signal is finally sent to the receiving end of the RF transceiver 20 through the second output port for subsequent processing.

[0058] In this way, the isolation circuit 60 can ensure that the transmission signal outputted from the RF transceiver 20 through the transmitting end can be filtered by the notch filter and then pass through the transmission channel to the antenna port 10 without hindrance and be sent to the outside, and at the same time, it can also ensure that the receiving signal is transmitted from the antenna port 10 through the receiving channel to the receiving end of the RF transceiver 20. The transmission signal and the receiving signal will not affect each other due to the overlapping working frequency bands.

[0059] Combined with the above embodiments, refer to Figure 6The test circuit includes a transceiver, a power amplifier PA, a switching circuit 40SPDT RF switch, a filtering circuit 30Notch filter, a duplexer and an antenna port 10ANT. Among them, the duplexer is an isolation circuit 60. When single band testing and CA testing are required, the isolation circuit 60 can be electrically connected to the first contact and the second contact of the switching circuit 40 respectively to ensure that during the single band test, the internal control circuit of the RF transceiver 20 controls the switching circuit 40 to conduct the path between its own fixed end and the second contact, so that the transmission signal output by the RF transceiver 20 is amplified by the power amplifier circuit 50 (PA) and then output to the isolation circuit 60, that is, the isolation circuit 60 is isolated and then output to the antenna port 10. Similarly, when the communication system is in CA testing, the internal control circuit of the RF transceiver 20 controls the switching circuit 40 to conduct the path between the fixed end and the first contact, so that the transmission signal output by the RF transceiver 20 is output to the notch filter for filtering after being amplified by the PA, and the notch filter outputs the processed signal to the isolation circuit 60, so that the isolation circuit 60 outputs it to the antenna port 10 and sends it to the outside.

[0060] The setting of the isolation circuit 60 ensures that both the transmission and reception of signals can be carried out simultaneously without interfering with each other, whether in single-band testing or CA testing. In this way, full-duplex communication is allowed to be implemented in a device of an antenna system, that is, data can be sent and received at the same time, thereby effectively improving the capacity and efficiency of the communication system.

[0061] In one embodiment, reference Figure 2 The switching switch circuit 40 includes a first switching switch 41 and a second switching switch 42, the first switching switch 41 electrically connects the RF transceiver 20 and the filter circuit 30, and the second switching switch 42 electrically connects the filter circuit 30 and the antenna port 10.

[0062] Among them, the fixed end of the first switching switch 41 is electrically connected to the output end of the RF transceiver 20, the active end of the first switching switch 41 includes a first contact and a second contact, the first contact is electrically connected to the filter circuit 30, the fixed end of the second switching switch 42 is electrically connected to the antenna port 10, the active end of the second switching switch 42 includes a third contact and a fourth contact, the third contact is electrically connected to the filter circuit 30, and the fourth contact is electrically connected to the second contact of the first switching switch 41.

[0063] In this embodiment, the first switch 41 and the second switch 42 can be implemented by a switch tube such as a PIN diode switch, a field effect transistor, or a switch device such as a relay or a contactor, or a radio frequency switch SPDT. In this embodiment, the second switch 42 includes any one of an SP2T radio frequency switch, an SP4T radio frequency switch, and an SP6T radio frequency switch.

[0064] Taking the example that the first switching switch 41 is a SPDT1 RF switch and the second switching switch 42 is a SPDT2 RF switch, combined with the content of the above embodiments, the SPDT1 RF switch can be directly added as the first switching switch 41, the SPDT2 RF switch as the second switching switch 42 and the notch filter as the filtering circuit 30 in the signal path of the Single Band test, wherein the input end of the SPDT1 RF switch is the fixed end of the switching switch circuit 40 electrically connected to the output end of the power amplifier circuit 50, the first output end of the SPDT1 RF switch is electrically connected to the first input end of the SPDT2 RF switch (the fourth contact of the second switching switch 42) as the second contact of the switching switch circuit 40, the second output end of the SPDT1 RF switch is electrically connected to the second input end of the SPDT2 RF switch (the third contact of the second switching switch 42) as the first contact of the switching switch circuit 40 via the notch filter, and the controlled end of the SPDT1 RF switch and the controlled end of the SPDT2 RF switch are both electrically connected to the control end of the RF transceiver 20.

[0065] In this embodiment, the controlled end of the first switch 41 is electrically connected to the control end of the RF transceiver 20, and the controlled end of the second switch 42 is electrically connected to the control end of the RF transceiver 20, so that the RF transceiver 20 controls the switching logic of the first switch 41 and the second switch 42 based on the working state.

[0066] In combination with the above embodiments, the isolation circuit 60 includes a duplexer, the fixed end of the second switch 42 is electrically connected to the transmitting port of the duplexer, and the output end of the duplexer is electrically connected to the antenna port 10 .

[0067] Specifically, refer to Figure 5 and Figure 6During the Single Band test, the control circuit inside the RF transceiver 20 outputs a GPIO control signal to control the SPDT1 RF switch to turn on the path between its own input terminal and the first output terminal, and to turn on the SPDT2 RF switch to turn on the path between the first input terminal and its own output terminal, so that the transmission signal output by the RF transceiver 20 is amplified by the power amplifier circuit 50 and then directly goes to the second isolation circuit for isolation processing after passing through the SPDT1 RF switch and the SPDT2 RF switch, and then is transmitted to the outside through the antenna port 10; similarly, under the band-edge CA test, if the distance between the working frequency bands of the transmitting (TX) signal and the receiving (RX) signal is only 20MHZ in some frequency bands, for example, in this embodiment, the working frequency band range of the transmitting signal is 1850~1910MHz. That is, in the B2 working frequency band, the TX frequency band is 1850~1910MHz, and the RX frequency band is 1930~1990MHz. At this time, since the gap between the TX and RX frequency bands is very small, the SAW cannot suppress the noise of TX falling on RX sufficiently, affecting the sensitivity and T-put index of SCC. Therefore, during the CA test, the control circuit inside the RF transceiver 20 controls the path between the fixed end of the first switching switch 41 and the first contact, that is, controls the SPDT1 RF switch to turn on the path between its own input end and the second output end, and at the same time turns on the path between the fixed end of the second switching switch 42 and the third contact, that is, turns on the SPDT2 RF switch to turn on the path between the second input end and its own input end, so that the transmission signal output by the RF transceiver 20 is amplified by the power amplifier circuit 50 and then reaches the filter circuit 30 for filtering after passing through the SPDT1 RF switch, wherein the filter circuit 30 includes a notch filter, the input end of the notch filter is electrically connected to the first contact of the first switching switch 41, and the output end of the notch filter is electrically connected to the third contact of the second switching switch 42. In this way, when the RF transceiver 20 controls the first switching switch 41 to turn on the path between the fixed end and the first contact based on the working state, the transmission signal is sent from the RF transceiver 20 to the notch filter. At the same time, the RF transceiver 20 controls the second switching switch 42 to turn on the path between the fixed end and the third contact based on the working state, so that the transmission signal after filtering by the notch filter is output to the second isolation circuit of the duplexer through the SPDT2 RF switch, and then output to the outside through the antenna port 10. It should be noted that when in the CA test state, the receiving signal reaches the RF transceiver 20 through the first isolation circuit through another path. The transmitting signal and the receiving signal do not interfere with each other. In this way, when testing the band-edge CA, the transmitting front end is switched to the path where the notch filter is located, which increases the suppression of the noise of TX falling on RX, thereby improving the sensitivity index of SCC.

[0068] It is understandable that at room temperature, in order to ensure the consistency of product indicators and the performance of high and low temperatures, the power of the single band is usually the target power ±1dB, while the power under CA only needs to meet the allowable deviation range of the target power (-3dB, +2dB). Therefore, although adding a notch filter will increase the loss of the transmission signal frequency band and lead to a reduction in transmission power, since the lower limit of the allowable deviation range of the target power under CA is -3dB, it is reduced by 2dB from the original -1dB, so meeting the requirements of 3GPP will not have a significant impact. Among them, the target power is the rated carrier output power.

[0069] Through the above settings, it can be ensured that the single band test is performed according to the original path to ensure the TX performance during the single band test. In addition, under the CA test, when the frequency spacing between the transmitting signal and the receiving signal is small, the suppression of the transmitting signal falling on the receiving signal is increased, and the interference of the transmitting signal on the receiving signal is reduced, thereby improving the sensitivity of SCC to ensure the T-put index and networking quality of CA when it is actually used in the live network, and improve the user experience.

[0070] The above description is only an optional embodiment of the utility model, and does not limit the patent scope of the utility model. All equivalent structural changes made by using the contents of the utility model specification and drawings under the inventive concept of the utility model, or directly / indirectly used in other related technical fields are included in the scope of the utility model.

Claims

1. A test circuit, characterized in that: The test circuit includes an antenna port for accessing an antenna and a radio frequency transceiver, and further includes: A switching circuit, the switching circuit electrically connecting the radio frequency transceiver and the filter circuit, the switching circuit being used for switching the transmission signal to be output to the filter circuit when there is interference between the reception signal and the transmission signal of the radio frequency transceiver; A filter circuit is electrically connected to the switching circuit and the antenna port, and is used for filtering the transmission signal and then outputting it to the antenna port.

2. The test circuit according to claim 1, characterized in that: The switching circuit includes a first switching switch and a second switching switch, the first switching switch electrically connects the RF transceiver and the filter circuit, and the second switching switch electrically connects the filter circuit and the antenna port.

3. The test circuit according to claim 2, characterized in that: The fixed end of the first switching switch is electrically connected to the output end of the RF transceiver, the active end of the first switching switch includes a first contact and a second contact, the first contact is electrically connected to the filter circuit, the fixed end of the second switching switch is electrically connected to the antenna port, the active end of the second switching switch includes a third contact and a fourth contact, the third contact is electrically connected to the filter circuit, and the fourth contact is electrically connected to the second contact of the first switching switch.

4. The test circuit according to claim 2, characterized in that: The controlled end of the first switch is electrically connected to the control end of the RF transceiver, and the controlled end of the second switch is electrically connected to the control end of the RF transceiver, so that the RF transceiver controls the switching logic of the first switch and the second switch based on the working state.

5. The test circuit according to claim 1, characterized in that: The test circuit further comprises: A power amplifier circuit, wherein an input end of the power amplifier circuit is electrically connected to an output end of the radio frequency transceiver, and an output end of the power amplifier circuit is electrically connected to a fixed end of the switching circuit; The power amplifier circuit is used to amplify the transmission signal output by the radio frequency transceiver.

6. The test circuit according to claim 2, characterized in that: The test circuit further comprises: An isolation circuit is electrically connected to the filter circuit and the antenna port, and is used to isolate the transmit signal and the receive signal of the radio frequency transceiver.

7. The test circuit according to claim 6, characterized in that: The isolation circuit includes a duplexer, the fixed end of the second switch is electrically connected to the transmitting port of the duplexer, and the output end of the duplexer is electrically connected to the antenna port.

8. The test circuit according to claim 2, characterized in that: The filtering circuit includes a notch filter, an input end of the notch filter is electrically connected to a first contact of the first switch, and an output end of the notch filter is electrically connected to a third contact of the second switch.

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