A mobile phone RF circuit device suitable for B40 / B41 frequency bands

Abstract

The utility model provides a kind of mobile phone RF circuit device suitable for B40 / B41 frequency band, including RF circuit component, the RF circuit component includes high pass filter, low pass filter, radio frequency power amplifier, radio frequency transceiver and antenna;The signal output end of radio frequency transceiver is electrically connected with the input end of radio frequency power amplifier.The utility model replaces traditional double SAW filter by the combination of high pass filter+low pass filter+single radio frequency switch, reduces at least one SAW filter use, reduces component quantity, reduces PCB occupied area about 30%, adapts smartphone ultrathin compact design;Through radio frequency switch time-sharing switch transmission and receiving path, avoid signal link too long, HPF and LPF optimization filtering, reduce insertion loss and impedance matching complexity, improve signal stability;By omitting high-cost SAW filter, using LC lumped parameter filter etc., hardware cost reduces about 30%, and reduces component quantity and assembly procedure, reduces scale production procurement and process cost.

Description

Technical Field

[0001] This utility model relates to the field of mobile phone radio frequency communication technology, and in particular to a mobile phone RF circuit device suitable for the B40 / B41 frequency band. Background Technology

[0002] In the field of LTE communication, the B40 / B41 band (2300-2690MHz) is an important frequency band for TDD-LTE and is widely used in wireless communication of smartphones. Traditional mobile phone RF circuits typically employ a discrete component architecture for signal processing in this band. A typical design requires separate transceiver filters (TRX SAW) to process the transmit and receive signals of the B40 and B41 bands respectively. For example, a traditional circuit block diagram would need to include components such as a B40 TRX SAW, a B41 TRX SAW, independent RF switches, and a power amplifier. This approach suffers from the following technical bottlenecks:

[0003] First, the use of multiple SAW filters leads to a surge in the number of RF front-end components, occupying too much PCB layout space and making it difficult to adapt to the design trend of ultra-thin and compact smartphones.

[0004] Secondly, both the transmission and reception paths rely on cascaded independent filters, resulting in excessively long signal links and increased insertion loss. At the same time, the impedance matching problem caused by the cascaded multi-components further affects signal stability.

[0005] In addition, SAW filters are expensive, and the cost of materials (BOM) is increased by the matching RF switches, matching components, etc., especially in large-scale production, where the cost disadvantage is more significant.

[0006] Therefore, a mobile phone RF circuit device suitable for the B40 / B41 frequency band is proposed. Utility Model Content

[0007] In view of this, the present invention aims to provide a mobile phone RF circuit device suitable for the B40 / B41 frequency band, so as to solve or alleviate the technical problems existing in the prior art, or at least provide a beneficial alternative.

[0008] The technical solution of this utility model embodiment is implemented as follows: a mobile phone RF circuit device suitable for the B40 / B41 frequency band, including an RF circuit assembly, wherein the RF circuit assembly includes a high-pass filter, a low-pass filter, an RF power amplifier, an RF transceiver, an RF switch and an antenna;

[0009] The signal output terminal of the RF transceiver is electrically connected to the input terminal of the RF power amplifier. The signal input terminal of the RF transceiver is electrically connected to the output terminal of the low-pass filter. The RF transceiver is used to generate and process B40 / B41 band signals. The output terminal of the RF power amplifier is electrically connected to the input terminal of the high-pass filter. The passband frequency of the high-pass filter is 2300-2690MHz. The output terminal of the high-pass filter is electrically connected to the signal input terminal of the RF switch. The antenna terminal of the RF switch is connected to the antenna port. The signal output terminal of the RF switch is electrically connected to the input terminal of the low-pass filter. The passband frequency of the low-pass filter is 673-2690MHz. The RF switch has a time-division switching function and is used to switch the transmission and reception paths of B40 / B41 band signals.

[0010] More preferably, the high-pass filter is a thin-film bulk acoustic wave filter with an insertion loss ≤1.5dB and out-of-band rejection ≥30dB.

[0011] More preferably, the low-pass filter is an LC lumped parameter filter with a cutoff frequency of 2700MHz.

[0012] More preferably, the gain of the radio frequency power amplifier is ≥25dB, and the output power is controlled at 23dBm±2dB.

[0013] More preferably, the RF switch is a single-pole double-throw structure with a switching speed ≤50ns and an insertion loss ≤0.8dB@2.4GHz.

[0014] More preferably, a 50Ω impedance matching line is used between the RF power amplifier and the high-pass filter.

[0015] More preferably, the antenna end of the RF switch is positioned close to the antenna port, and shielded wiring is used between the low-pass filter and the RF transceiver.

[0016] More preferably, the device is suitable for TDD (Time Division Multiple Access) operation mode, and the radio frequency switch switches the transmission and reception paths in a time-division manner.

[0017] The present invention has the following advantages due to the adoption of the above technical solution:

[0018] 1. This utility model replaces the traditional dual SAW filter with a combination of high-pass filter + low-pass filter + single RF switch, reducing the use of at least one SAW filter, significantly reducing the number of components, and reducing the PCB area occupied by about 30%, effectively adapting to the design requirements of ultra-thin and compact smartphones.

[0019] 2. This utility model uses a radio frequency switch to time-division switch the transmission and reception paths, avoiding the problem of excessively long signal links caused by traditional multi-component cascading; at the same time, HPF and LPF are optimized for transmission / reception frequency bands respectively, reducing insertion loss and impedance matching complexity, and improving signal purity and transmission stability.

[0020] 3. This utility model reduces hardware costs by approximately 30% by omitting the high-cost SAW filter and using low-cost components such as the LC lumped parameter filter; at the same time, it reduces the number of components and assembly steps, further reducing procurement and process costs in large-scale production.

[0021] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the present invention will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A block diagram of a novel B40 / B41 band RF circuit design provided for embodiments of this utility model;

[0024] Figure 2 A block diagram of a conventional B40 / B41 band RF circuit design provided for an embodiment of this utility model.

[0025] Reference numerals: 1. RF circuit assembly; 11. High-pass filter; 12. Low-pass filter; 13. RF power amplifier; 14. RF transceiver; 15. RF switch; 16. Antenna. Detailed Implementation

[0026] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this invention. Therefore, the drawings and description are considered exemplary in nature and not restrictive.

[0027] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0028] like Figure 1As shown, this utility model embodiment provides a mobile phone RF circuit device suitable for the B40 / B41 frequency band, including an RF circuit component 1, which includes a high-pass filter 11, a low-pass filter 12, an RF power amplifier 13, an RF transceiver 14, an RF switch 15, and an antenna 16.

[0029] The signal output terminal of RF transceiver 14 is electrically connected to the input terminal of RF power amplifier 13, and the signal input terminal of RF transceiver 14 is electrically connected to the output terminal of low-pass filter 12. RF transceiver 14 is used to generate and process B40 / B41 band signals. The output terminal of RF power amplifier 13 is electrically connected to the input terminal of high-pass filter 11, and the passband frequency of high-pass filter 11 is 2300-2690MHz. The output terminal of high-pass filter 11 is electrically connected to the signal input terminal of RF switch 15. The antenna terminal of RF switch 15 is connected to the port of antenna 16. The signal output terminal of RF switch 15 is electrically connected to the input terminal of low-pass filter 12, and the passband frequency of low-pass filter 12 is 673-2690MHz. RF switch 15 has a time-division switching function and is used to switch the transmission and reception paths of B40 / B41 band signals.

[0030] Among them, the high-pass filter 11 has a passband of 2300-2690MHz, which only allows the transmit frequency band signal to pass through and filters out low-frequency interference (such as Wi-Fi and GSM signals); the low-pass filter 12 has a passband of 673-2690MHz, which covers the B40 / B41 receive frequency band (2300-2690MHz) and compatible frequency bands such as B34 / B39, and filters out high-frequency noise.

[0031] In one embodiment, specifically: the high-pass filter 11 is a thin-film bulk acoustic wave filter with an insertion loss ≤1.5dB and out-of-band rejection ≥30dB;

[0032] Insertion loss directly affects the power efficiency of the transmitted signal. The output power of the RF power amplifier 13 is 23dBm±2dB. After passing through the thin-film bulk acoustic wave filter, the signal power loss is ≤1.5dB, that is, the antenna-end transmit power is ≥21.5dBm, which meets the requirements of the LTE system for the transmit power of the mobile terminal (typical value ≥20dBm). The low loss characteristic avoids the loss superposition problem caused by multi-stage cascading of traditional SAW filters (such as the B40 TRX SAW insertion loss ≥2dB in the traditional scheme, and the total loss after multi-stage cascading ≥4dB), thus improving the overall efficiency of the RF link.

[0033] In one embodiment, specifically: the low-pass filter 12 is an LC lumped parameter filter with a cutoff frequency of 2700MHz;

[0034] The LC lumped parameter filter consists of inductors (L) and capacitors (C), requiring no complex semiconductor processes and significantly lower cost than SAW or FBAR filters, thus meeting the core objective of this invention: "reducing hardware costs." The received signal frequency in the B40 / B41 band is 2300-2690MHz, while the LC lumped parameter filter can achieve low insertion loss (≤2dB) and linear phase response within the 673-2700MHz range through proper selection (such as multilayer ceramic capacitors and wire-wound inductors), meeting the filtering requirements of the received signal.

[0035] In one embodiment, specifically: the gain of the RF power amplifier 13 is ≥25dB, and the output power is controlled at 23dBm±2dB;

[0036] Among them, 23dBm±2dB is the typical transmit power range of mobile terminals in LTE systems, which meets the requirements of base station receiving sensitivity and electromagnetic radiation (SAR) specifications, ensuring communication quality while complying with regulatory restrictions; the ±2dB tolerance control can avoid signal distortion or adjacent channel interference caused by excessive power fluctuations. Especially in TDD mode, stable transmit power helps to improve the reliability of time division multiplexing.

[0037] In one embodiment, specifically: the RF switch 15 is a single-pole double-throw structure with a switching speed ≤50ns and an insertion loss ≤0.8dB@2.4GHz;

[0038] Among them, the single-pole double-throw (SPDT) structure can realize time-division switching of the transmit (TX) and receive (RX) signal paths:

[0039] Transmit time slot: Open the path "RF power amplifier 13 → high-pass filter 11 → antenna 16";

[0040] Receive time slot: Open the path "Antenna 16 → Low-pass filter 12 → RF transceiver 14";

[0041] This structure is perfectly matched with the TDD (Time Division Multiple Access) mode. It avoids signal collisions through time division multiplexing and simplifies the complex topology of traditional multi-component cascade (such as the traditional solution which requires an independent RF switch 15 in conjunction with dual SAW filters).

[0042] In one embodiment, specifically: a 50Ω impedance matching line is used between the RF power amplifier 13 and the high-pass filter 11;

[0043] Among them, 50Ω is the standard characteristic impedance of the radio frequency circuit. Through matching circuit design, the output impedance of the power amplifier can be made consistent with the input impedance of the high-pass filter 11, reducing the signal reflection coefficient and avoiding signal power loss due to impedance mismatch (reflected power will be converted into heat or interference).

[0044] In one embodiment, specifically: the antenna end of the RF switch 15 is positioned close to the port of the antenna 16, and shielded wiring is used between the low-pass filter 12 and the RF transceiver 14.

[0045] Specifically, the antenna end of the RF switch 15 is positioned close to the port of the antenna 16. Its core purpose is to shorten the RF signal transmission path, reduce insertion loss and electromagnetic interference during signal transmission, and optimize the impedance matching of the RF link (such as a 50Ω impedance design) to improve the efficiency of transmitting and receiving signals. The low-pass filter 12 and the RF transceiver 14 are connected by shielded wiring, mainly to isolate high-frequency electromagnetic interference (EMI). Since the received signal has already been filtered out by high-frequency noise after passing through the low-pass filter 12, the shielded wiring can prevent it from being subjected to secondary interference from external electromagnetic noise during transmission to the RF transceiver 14, ensuring the purity of the received signal and improving demodulation performance.

[0046] In one embodiment, specifically: the device is adapted to TDD (Time Division Multiple Access) operating mode, and switches the transmit and receive paths in 15-minute intervals via a radio frequency switch;

[0047] Specifically, in TDD mode, the transmit and receive signals operate in different time slots:

[0048] Transmit time slot: RF switch 15 turns on the path "RF power amplifier 13 → high-pass filter 11 → antenna 16";

[0049] Receive time slot: RF switch 15 opens the path "antenna 16 → low-pass filter 12 → RF transceiver 14";

[0050] The time-division multiplexing mechanism ensures that there is no conflict between transmitted and received signals.

[0051] When this utility model is in operation:

[0052] Transmission Procedure (B40 / B41 Band Signal Generation to Transmission via Antenna 16)

[0053] The RF transceiver 14, as the core of signal processing, internally generates a transmit signal in the B40 / B41 band (frequency range 2300-2690MHz) and converts it into an analog electrical signal. At this point, the signal power is relatively weak (approximately -2 to 2dBm). This signal is transmitted to the input of the RF power amplifier 13 through the signal output terminal, completing the first step of the transmission process. The RF power amplifier 13 amplifies the received weak signal with a gain ≥25dB, increasing the signal power to 23dBm±2dB (meeting the typical power requirements of mobile phone RF transmission). The amplified signal is then transmitted to... The input terminal of the high-pass filter 11; the high-pass filter 11 is a thin-film bulk acoustic wave filter (FBAR) with a passband frequency of 2300-2690MHz, allowing only the transmission signals of the B40 / B41 band to pass through, filtering out low-frequency interference signals (such as noise below 2300MHz); the filtered clean signal is transmitted to the signal input terminal of the RF switch 15 through the output terminal; the RF switch 15 switches to the transmit mode in the TDD transmit time slot, and its internal conduction signal input terminal → antenna terminal path is turned on; the signal is transmitted to the antenna 16 through the antenna terminal, and the antenna 16 radiates the RF signal into space, completing the transmission process;

[0054] Reception process (B40 / B41 band signals are received and processed from antenna 16)

[0055] Antenna 16 captures B40 / B41 band RF signals (frequency range 673-2690MHz, including B40 / B41 receiving bands and other compatible bands such as B34 / B39) in space and transmits them to the antenna end of RF switch 15. RF switch 15 switches to receive mode in the TDD receiving time slot, internally opening the path from the antenna end to the signal output end, and the signal enters the input end of low-pass filter 12. Low-pass filter 12 is an LC lumped parameter filter with a cutoff frequency of 2700MHz, allowing signals of 673-2690MHz to pass through while filtering out high-frequency interference (such as noise from other bands) above 2690MHz. The filtered signal is transmitted to the signal input end of RF transceiver 14 through the output end. RF transceiver 14 amplifies, filters, and performs analog-to-digital conversion (ADC) on the received signal, converting the analog signal into a digital signal so that the mobile phone baseband system can demodulate and decode it, ultimately restoring it into voice, data, and other information.

[0056] like Figure 2 As shown, a traditional B40 / B41 band RF circuit includes the following key components:

[0057] Antenna: Used to transmit and receive radio frequency signals;

[0058] B40 TRX SAW Filter: Independently processes transmit and receive signals in the B40 band (2300-2400MHz);

[0059] B41 TRX SAW Filter: Independently processes transmit and receive signals in the B41 band (2500-2690MHz);

[0060] Radio frequency power amplifier (PA): amplifies the power of the transmitted signal;

[0061] RF switch: Switches the transmit and receive signal paths;

[0062] Radio frequency transceiver: generates and processes radio frequency signals.

[0063] The signal connection relationship in the traditional solution is as follows:

[0064] Transmission path (taking the B40 band as an example)

[0065] The RF transceiver generates a B40 band transmit signal → the RF power amplifier amplifies the signal → the B40 TRX SAW filter filters the signal → the RF switch switches to the antenna path → the antenna transmits the signal.

[0066] Reception path (taking B41 band as an example)

[0067] Antenna receives B41 band signal → RF switch switches to B41 TRX SAW filter path → B41 TRX SAW filter filters → RF transceiver processes signal;

[0068] Among them, the B40 and B41 frequency bands each use independent TRX SAW filters to form two independent transmit and receive links;

[0069] Each link contains components such as "SAW filter → PA → SAW filter → RF switch", resulting in a complex circuit topology.

[0070] Compared with traditional B40 / B41 band RF circuits, the RF circuit device for mobile phones provided by this utility model has the following advantages:

[0071] 1. It eliminates the need for the B40 TRX SAW and B41 TRX SAW found in traditional solutions, achieving equivalent functionality through a combination of "HPF+LPF+single RF switch," thus reducing the number of components.

[0072] 2. Saves on SAW filter costs and PCB space, meeting the miniaturization and low-cost requirements of smartphones;

[0073] 3. The combination of FBAR and LC filters has low insertion loss (HPF≤1.5dB, LPF≤2dB) and high out-of-band rejection (HPF≥30dB) in the passband, ensuring signal purity.

[0074] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in this utility model, and these should all be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A mobile phone RF circuit device suitable for the B40 / B41 frequency band, characterized in that: It includes an RF circuit assembly (1), which includes a high-pass filter (11), a low-pass filter (12), an RF power amplifier (13), an RF transceiver (14), an RF switch (15), and an antenna (16); The signal output terminal of the RF transceiver (14) is electrically connected to the input terminal of the RF power amplifier (13). The signal input terminal of the RF transceiver (14) is electrically connected to the output terminal of the low-pass filter (12). The RF transceiver (14) is used to generate and process B40 / B41 band signals. The output terminal of the RF power amplifier (13) is electrically connected to the input terminal of the high-pass filter (11). The passband frequency of the high-pass filter (11) is 2300-2690MHz. The output terminal of the oscillator (11) is electrically connected to the signal input terminal of the RF switch (15). The antenna terminal of the RF switch (15) is connected to the port of the antenna (16). The signal output terminal of the RF switch (15) is electrically connected to the input terminal of the low-pass filter (12). The passband frequency of the low-pass filter (12) is 673-2690MHz. The RF switch (15) has a time-division switching function. The RF switch (15) is used to switch the transmission and reception paths of the B40 / B41 band signals.

2. The mobile phone RF circuit device suitable for the B40 / B41 frequency band according to claim 1, characterized in that: The high-pass filter (11) is a thin-film bulk acoustic filter with an insertion loss ≤1.5dB and out-of-band rejection ≥30dB.

3. The mobile phone RF circuit device suitable for the B40 / B41 frequency band according to claim 1, characterized in that: The low-pass filter (12) is an LC lumped parameter filter with a cutoff frequency of 2700MHz.

4. The mobile phone RF circuit device suitable for the B40 / B41 frequency band according to claim 1, characterized in that: The gain of the radio frequency power amplifier (13) is ≥25dB ​​and the output power is controlled at 23dBm±2dB.

5. A mobile phone RF circuit device suitable for the B40 / B41 frequency band according to claim 1, characterized in that: The radio frequency switch (15) is a single-pole double-throw structure with a switching speed ≤50ns and an insertion loss ≤0.8dB@2.4GHz.

6. A mobile phone RF circuit device suitable for the B40 / B41 frequency band according to claim 1, characterized in that: A 50Ω impedance matching line is used between the RF power amplifier (13) and the high-pass filter (11).

7. A mobile phone RF circuit device suitable for the B40 / B41 frequency band according to claim 1, characterized in that: The antenna end of the RF switch (15) is positioned close to the port of the antenna (16), and the low-pass filter (12) and the RF transceiver (14) are connected by shielded wiring.

8. A mobile phone RF circuit device suitable for the B40 / B41 frequency band according to claim 1, characterized in that: The device is suitable for TDD (Time Division Multiple Access) operation mode, and the transmission and reception paths are switched in time-division by the radio frequency switch (15).

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