Bridge-based frequency division duplex balanced low noise amplifier and radio frequency receiver

Abstract

The invention discloses a bridge-based frequency division duplex balanced low noise amplifier and a radio frequency receiver, comprising a bridge A and a bridge B. The bridge A and the bridge B are both dual-frequency bridges, a port P1 of the bridge A receives signals, a port P4 of the bridge A is connected with a load, a port P2 and a port P3 are respectively connected with an input end of the low noise amplifier, and a port P2 and a port P4 of the bridge B are respectively connected with an output end of the low noise amplifier. The output end of the low noise amplifier is respectively connected with a port P5 and a port P8 of the bridge B, a port P6 outputs a frequency f1 signal, a port P7 can output a frequency f2 signal, or the port P6 outputs the frequency f2 signal, and the port P7 outputs the frequency f1 signal; the output ports of the bridge A are opposite in phase, and the output ports of the bridge B are the same in phase; and the duplex effect is realized under the working of the two bridges. Compared with the design of a traditional balanced duplex low-noise amplifier, an additional traditional duplexer is not needed to realize a duplex function, so that the system integration level is improved, the component cost is reduced, and the system performance is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of radio frequency communication, and particularly relates to a frequency division duplex balanced low-noise amplifier based on a bridge and a radio frequency receiver. Background Art

[0002] Currently, duplexers are commonly used in the design of radio frequency receivers to achieve precise separation and efficient transmission of dual-frequency signals. In a multi-band receiver system, the duplexer works in coordination with its internally integrated transmit filter and receive filter to effectively suppress spurious signals in non-target frequency bands and accurately allocate signals in different frequency bands to their respective independent transceiver channels. This ingenious design based on frequency division enables the radio frequency front-end to support the transmission of high-frequency signals and the reception of low-frequency signals simultaneously, or to achieve concurrent processing of multiple communication bands. The core role of the duplexer in the system is mainly reflected in the following three aspects: First, transceiver isolation. It uses the frequency selectivity of the band-pass filter to strictly physically isolate the high-power signals in the transmit link from the weak signals in the receive link, effectively avoiding reverse interference of the transmit signal on the front-end of the receiver. Second, path optimization. In application scenarios with limited space such as cellular base stations, the duplexer multiplexes the same antenna to complete the transceiver tasks of multi-band signals, significantly reducing the number of antennas and the system complexity. Third, anti-aliasing processing. Combining with the duplexing mechanism in the frequency division duplex (FDD) mode, the duplexer uses the guard bandwidth between frequency bands to effectively suppress adjacent frequency interference and image frequency interference, ensuring the spectral purity of each signal path.

[0003] However, the use of a duplexer also brings some challenges. First, the addition of a duplexer usually leads to a more complex system structure, requiring more components for interconnection and debugging. Second, the duplexer increases the system cost, especially in high-frequency and high-power applications, where the design and manufacturing cost of the duplexer is relatively high. In addition, the volume and size of the duplexer also increase the overall size of the radio frequency receiver, affecting the miniaturization requirements of the system. More importantly, the duplexer itself may introduce additional signal losses. Especially in the transmission of high-frequency signals, the duplexer will cause a certain degree of insertion loss, thereby affecting the overall performance of the system.

[0004] As the core of the receiver, the loss at the front stage of the low-noise amplifier (LNA) will greatly affect the noise performance of the system. In recent years, integrated solutions have become an important direction for research and development to improve the noise performance of the low-noise amplifier. Summary of the Invention

[0005] To solve the problems existing in the prior art, the present invention provides a dual-band and duplex balanced low-noise amplifier with integrated functions. The core concept is to achieve the dual-band and duplex functions through a clever coupler design, without the need for an additional traditional duplexer, thereby improving the integration and performance of the RF receiver and realizing the miniaturization of the circuit.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a frequency-division duplex balanced low-noise amplifier based on a bridge, including bridge A and bridge B. Both bridge A and bridge B are dual-frequency bridges. The port P1 of bridge A receives a signal, the port P4 is connected to a load, the ports P2 and P3 are respectively connected to the input ends of the low-noise amplifier, the output ends of the low-noise amplifier are respectively connected to the ports P5 and P8 of bridge B, the port P6 outputs a signal of frequency f1, the P7 port can output a signal of frequency f2 or the P6 port outputs a signal of frequency f2, and the P7 port outputs a signal of frequency f1; the output ports of bridge A have opposite phases, and the output ports of bridge B have the same phase.

[0007] Further, the operating frequencies of bridge A are f1 and f2, and a 90-degree coupler is loaded with four quarter-wavelength microstrip lines to achieve a 90-degree and -90-degree differential coupling for the dual frequencies. Among them, two half-wavelength @f0 microstrip lines TL1 and two half-wavelength @f0 microstrip lines TL3 are connected to form a traditional 90-degree bridge. Four quarter-wavelength @f0 microstrip lines TL2 cross to connect the port P1 and the port P3, and connect the port P2 and the port P4. At the same time, the port P1 and the port P2, and the port P4 and the port P3 are connected by a half-wavelength @f0 microstrip line TL1, and the port P1 and the port P4, and the port P2 and the port P3 are connected by a half-wavelength @f0 microstrip line TL3.

[0008] Further, when the input port is port P1 and the circuit operates at frequencies f1 and f2, at the operating frequency f1, there is a 90-degree phase difference between the through port P2 and the coupled port P3 of bridge A. At the operating frequency f2, there is a -90-degree phase difference between the through port P2 and the coupled port P3 of bridge A, or at the operating frequency f1, there is a -90-degree phase difference between the through port P2 and the coupled port P3 of bridge A, and at the operating frequency f2, there is a 90-degree phase difference between the through port and the coupled port of bridge A.

[0009] Further, f1, f2, and the bandwidth of the operating frequency band can all be controlled by adjusting the impedances of the three microstrip lines: the half-wavelength @f0 microstrip line TL1, the quarter-wavelength @f0 microstrip line TL2, and the half-wavelength @f0 microstrip line TL3.

[0010] Further, the bridge B is implemented by a 90-degree coupler loaded with four quarter-wavelength open stubs to achieve dual-frequency 90-degree differential coupling. Among them, two quarter-wavelength @f0 microstrip lines TL2 and two quarter-wavelength @f0 microstrip lines TL3 are connected as shown in the figure to form a traditional 90-degree bridge. Four quarter-wavelength @f0 microstrip lines TL1 are loaded between the input port and the quarter-wavelength @f0 microstrip lines TL2 and TL3.

[0011] Further, the bridge B is a dual-frequency bridge with operating frequencies of f1 and f2. At the operating frequency f1, there is a 90-degree phase difference between the through port P6 and the coupled port P7 of the bridge B. At the operating frequency f2, there is also a 90-degree phase difference between the through port P6 and the coupled port P7 of the bridge B.

[0012] Further, when the signal frequency received at port P1 is f1&f2, port P6 and port P7 output f1-frequency signals and f2-frequency signals respectively, or output f2-frequency signals and f1-frequency signals respectively.

[0013] Further, among the two operating frequencies of bridge A and bridge B, f 1A is the same as f 1B and f 2A is the same as f 2B

[0014] Further, the low-noise amplifier adopts a two-stage transistor amplifier circuit.

[0015] The present invention can also provide a radio frequency receiver that employs the above-mentioned bridge-based frequency-division duplex balanced low-noise amplifier.

[0016] ​Compared with the prior art, the present invention has at least the following beneficial effects: The present invention realizes a balanced amplifier circuit through two different dual-frequency bridges A and B and two identical low-noise amplifiers LNA. At the same time, based on the phase characteristics of bridges A and B, the balanced amplifier integrates the duplex effect; it can significantly improve the performance of the RF receiver, reduce system complexity, and provide a new technical path for the implementation of future multi-band and high-frequency communication systems; in the design of the dual-frequency duplex balanced low-noise amplifier of the present invention, by integrating the dual-frequency duplex function in the 90-degree coupler part, the complex design of the traditional duplexer is omitted. Compared with the traditional balanced duplex low-noise amplifier design, there is no need for an additional traditional duplexer to achieve the duplex function. After removing the duplexer, the system integration degree is greatly improved, the overall design is more concise, and the cost is lower; through the balanced design, the anti-interference performance of the low-noise amplifier is improved, the influence of circulator mismatch on the front-stage balanced low-noise amplifier is solved, the stability and anti-interference characteristics of the system are improved, and efficient and stable communication is ensured; this design supports the simultaneous processing of signals in multiple frequency bands, improves the spectrum utilization rate, and meets the multi-band requirements of modern wireless communication systems; due to the removal of the duplexer, the design of the entire RF receiver becomes more compact, reducing the complexity and the number of components inside the system, and improving the maintainability and reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0018] Figure 1 It is a schematic circuit diagram of a frequency-division duplex balanced low-noise amplifier based on a bridge.

[0019] Figure 2 It is a circuit schematic diagram of bridge A used in the present invention.

[0020] Figure 3 It is the four-port S-parameter curve of bridge A used in the present invention.

[0021] Figure 4 It is the phase difference curve between port P2 and port P3 of bridge A used in the present invention.

[0022] Figure 5 It is a circuit schematic diagram of bridge B used in the present invention.

[0023] Figure 6 It is the four-port S-parameter curve of bridge B used in the present invention.

[0024] Figure 7 The phase difference curve between port P6 and port P7 of the bridge B used in the present invention.

[0025] Figure 8 The gain curve of the frequency division duplex balanced low noise amplifier based on the bridge.

[0026] Figure 9 The noise curve of the frequency division duplex balanced low noise amplifier based on the bridge.

[0027] Figure 10 The simulation result of the four-port noise figure of the frequency division duplex balanced low noise amplifier.

[0028] Figure 11 A block diagram of a radio frequency receiver based on the frequency division duplex balanced low noise amplifier described in the present invention. Specific embodiments

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] The foregoing and other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of the specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a more in-depth and specific understanding of the technical means and effects adopted by the present invention to achieve the predetermined purpose can be obtained. However, the accompanying drawings are only for reference and explanation, and are not used to limit the technical solutions of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0031] The present invention provides a frequency division duplex balanced low noise amplifier based on a bridge, including bridge A and bridge B. Both bridge A and bridge B are dual-frequency bridges. The signal is received at port P1 of bridge A, the load is connected to port P4, ports P2 and P3 are respectively connected to the input end of the low noise amplifier, the output end of the low noise amplifier is respectively connected to ports P5 and P8 of bridge B, frequency f1 signal is output at port P6, frequency f2 signal can be output at port P7 or frequency f2 signal is output at port P6, and frequency f1 signal is output at port P7; the output ports of bridge A are opposite in phase, and the output ports of bridge B are the same in phase.

[0032] The bridge A is based on a dual - frequency 90 - degree configuration with a 180 - degree phase difference between port 2 and port 3, that is, the phases are opposite; the bridge B is based on a dual - frequency 90 - degree configuration with a 0 - degree phase difference between port 2 and port 3, that is, the phases are the same. The circuit operates at two frequencies f1 and f2, which are selected as 1.58 GHz and 2.68 GHz here. The specific circuit framework is as Figure 1 shown. The signal is received at port P1 of bridge A, the load is connected to port P4, ports P2 and P3 are respectively connected to the input terminals of a low - noise amplifier (LNA). The output terminals of the LNA are respectively connected to input port P5 and input port P8 of bridge B. Port P6 can output the f1 signal, and port P8 can output the f2 signal, thus achieving a duplex effect under the operation of the two bridges.

[0033] Figure 1 Specifically, a circuit structure of bridge A that can achieve a positive / negative 90 - degree phase difference between port 2 and port 3 for dual - frequency coupling is as Figure 2 shown: It includes port P1, port P2, port P3, and port P4. Assuming port P1 is the input port, then port P2 is the through port, port P3 is the coupling port, and port P4 is the isolation port. This circuit is implemented by loading four quarter - wavelength microstrip lines on a traditional 90 - degree coupler to achieve a dual - frequency 90 - degree and - 90 - degree phase - difference coupling. Two half - wavelength @f0 microstrip lines TL1 and two half - wavelength @f0 microstrip lines TL3 are connected as shown to form a traditional 90 - degree bridge. Four quarter - wavelength @f0 microstrip lines TL2 cross - connect port P1 and port P3 and connect port P2 and port P4. At the same time, port P1 and port P2, and port P4 and port P3 are connected by half - wavelength @f0 microstrip line TL1, and port P1 and port P4, and port P2 and port P3 are connected by half - wavelength @f0 microstrip line TL3, as Figure 1 shown. This coupler is completely symmetric. When the input port is port P1 and the circuit operates at frequencies f1 and f2, equal - power distribution is achieved between port P2 and port P3. At the same time, when bridge A operates at frequency f1, there is a 90 - degree phase difference between port P2 and port P3. When bridge A operates at frequency f2, there is a - 90 - degree (270 - degree) phase difference between port P2 and port P3. The operating frequencies f1 and f2 of this circuit are related to f0, and f1, f2, and the bandwidth of the operating frequency band can all be freely controlled by adjusting the impedances of the three microstrip lines: half - wavelength @f0 microstrip line TL1, quarter - wavelength @f0 microstrip line TL2, and half - wavelength @f0 microstrip line TL3.

[0034] To verify the feasibility of the above - mentioned bridge A, the circuit structure is simulated, and the simulation results of the four - port S - parameters are as Figure 3As shown, it can be seen from the figure that the circuit well realizes the dual-frequency equal power splitting effect. Within the working frequency bands f1 and f2, the S11 of the circuit is less than -20 dB, indicating good matching characteristics. The transmission characteristics S between port 2 and port 3 of the circuit 21 and S 31 are almost the same in magnitude, about -3.39 dB or so, and the insertion loss is about 0.39 dB, which is basically caused by dielectric loss.

[0035] The phase difference between the through port 2 and the coupled port P3 of the bridge A is as Figure 4 shown. It can be seen from the figure that the phase difference between the through coupled port 2 and the coupled port 3 is 270 degrees (-90 degrees) at the working frequency f1 and 90 degrees at the working frequency f2, with good effects and meeting the expected design requirements.

[0036] Or at the working frequency f1, there is a 90-degree phase difference between the through port 2 and the coupled port 3 of the bridge A, and at the working frequency f2, there is a -90-degree phase difference between the through port 2 and the coupled port 3 of the bridge A.

[0037] The circuit of the bridge B is as Figure 5 shown, which includes port P5, port P6, port P7, and port P8. Assuming that port P5 is the input, then port P6 is the through port, port P7 is the coupled port, and port P8 is the isolation port. This circuit realizes dual-frequency 90-degree differential coupling by loading four quarter-wavelength open stubs on a traditional 90-degree coupler. Two quarter-wavelength @f0 microstrip lines TL2 and two quarter-wavelength @f0 microstrip lines TL3 are connected as shown to form a traditional 90-degree bridge, and four quarter-wavelength @f0 microstrip lines TL1 are loaded between the input port and the quarter-wavelength @f0 microstrip lines TL2 and the quarter-wavelength @f0 microstrip lines TL3, as Figure 1 shown. This coupler is completely symmetric. When the input port is port P5 and the circuit works at frequencies f1 and f2, equal power distribution is achieved between port P6 and port P7. At the same time, when the bridge B works at frequency f1, there is a 90-degree (-270-degree) phase difference between port P5 and port P6, and when the bridge B works at frequency f2, there is a 90-degree (-270-degree) phase difference between port P5 and port P6. The working frequencies f1 and f2 of this circuit are related to f0 and can be controlled by adjusting the impedances of the three microstrip lines: the quarter-wavelength @f0 microstrip line TL1, the quarter-wavelength @f0 microstrip line TL2, and the quarter-wavelength @f0 microstrip line TL3.

[0038] Figure 6The simulation results of the four-port S-parameters of coupler B. As can be seen from the figure, the circuit well realizes the dual-frequency equal power splitting effect. Within the operating frequency bands f1 and f2, the S11 of the circuit is less than -20 dB, indicating good matching characteristics. The transmission characteristics S 21 between port P6 and port P6 in the circuit 31 are almost the same in magnitude, approximately -3.41 dB, and the insertion loss is approximately 0.41 dB, which is basically caused by dielectric loss.

[0039] The phase difference between the through port P6 and the coupled port P7 of bridge B is as Figure 7 shown. As can be seen from the figure, the phase difference between the through coupled port 6 and the coupled port 7 is -270 degrees (90 degrees) at both the operating frequency f1 and the operating frequency f2, with good results and achieving the expected design effect.

[0040] Figure 8 The circuit schematic diagram of the low-noise amplifier LNA. To prove the feasibility of the theory described above, a broadband low-noise amplifier covering f1 and f2 is adopted in this design. The amplifier adopts a two-stage transistor amplification design. Among them, RF in is the input microstrip line, which is connected to the low-noise input matching network L1, C1, and then connected to the gate of transistor 1, and is connected to the gate bias circuit in the middle. The drain of the output of transistor 1 is connected to C2, R1, C3, C4, L2, R2, and is connected to the drain bias circuit in the middle. C3, L2, R2, C4 are the inter-stage matching networks. To achieve a larger gain and adjust the flatness, its output is connected to the gate of transistor 2, and at the same time, it is connected to the gate bias circuit of transistor 2 in the middle. The drain of the output of transistor 2 is connected to C5, R3, C6, L3, and is connected to the drain bias circuit of transistor 2 in the middle. C6, L3 are the output matching networks, which are connected to the RF out output microstrip line. The output matching network is used to make the reflection coefficient of port P2 less than -10 dB and adjust the gain flatness at the same time. C2, R1 and C5, R3 can improve the stability of the amplifier. At the same time, high-impedance lines are added to the sources of the two transistors to further improve the stability of the transistors. L g1 and L d1 and L b1 and L c1 are choke inductors. The simulation RF signal enters the DC path, and each DC path has two bypass capacitors to filter out low-frequency noise interference. The ADS software is used for simulation. The simulation results show that the low-noise amplifier can achieve a gain of more than 21 dB in the broadband range of 1.3 GHz - 2.9 GHz, and the simulation noise figure is between 0.4 dB - 0.6 dB, with good performance.

[0041] Figure 9The simulation results of the four-port S parameters of the frequency division duplex balanced low-noise amplifier. Through the ingenious design of the previous two dual-frequency bridges and the LNA simulation, as Figure 9 (a) shows, S 21 and S 31 The results show that at the working frequency band f1, the output is from port P6, and the circuit gain is 20.9 dB. At the working frequency band f2, the output is from port P7, and the circuit gain is 20.1 dB, indicating that the port balance is good and the expected duplex effect is achieved. As Figure 9 (b) shows, S 11 is less than -10 dB within the working frequency band, indicating good port matching.

[0042] Figure 10 The simulation results of the four-port noise figure of the frequency division duplex balanced low-noise amplifier. The results show that at the working frequency band f1, the output is from port P6, and the circuit noise figure is 0.72 dB. At the working frequency band f2, the output is from port P7, and the circuit noise figure is 0.96 dB, indicating good duplex effect of the circuit. And due to the system function integration, the use of the duplexer is reduced, and both the system gain and the noise performance are better.

[0043] Embodiment 2. Based on the frequency division duplex balanced low-noise amplifier based on the bridge, the present invention can also provide a radio frequency receiver, which does not require the use of a duplexer in the working state, improves the performance of the radio frequency receiver, and reduces the system complexity. Referring to Figure 11 , the radio frequency receiver includes a dual-frequency antenna, a filter, a frequency division duplex balanced low-noise amplifier based on the bridge, and a load. The antenna is sequentially connected to the switch filter and port P1 of the frequency division duplex balanced low-noise amplifier based on the bridge, and the load is connected to port P4.

[0044] In summary, the frequency-division duplex balanced low-noise amplifier based on a bridge provided by the present invention includes bridge A and bridge B. Both bridge A and bridge B are dual-frequency bridges. The port P1 of bridge A receives a signal, the port P4 is connected to a load, the ports P2 and P3 are respectively connected to the input end of the low-noise amplifier, the output ends of the low-noise amplifier are respectively connected to the ports P5 and P8 of bridge B, the port P6 outputs a signal of frequency f1, the port P7 can output a signal of frequency f2 or the port P6 outputs a signal of frequency f2 and the port P7 outputs a signal of frequency f1; the output ports of bridge A have opposite phases, and the output ports of bridge B have the same phase; through the ingenious application of a coupler, replacing the traditional duplexer, reducing the dependence on the duplexer, achieving the dual-frequency duplex effect. Compared with the traditional dual-frequency receiver architecture, this integrated design can not only reduce the cost and size of the system, but also reduce the interconnection loss and insertion loss of components, reduce the front-stage noise of the receiver, and improve the signal gain. Through this innovative design, the radio-frequency receiver can achieve higher integration and lower power consumption while improving the performance of the system. Since the duplexer is removed, the structure of the entire system becomes more compact and can adapt to a wider range of application scenarios, such as wireless communication, radar systems, and satellite communication and other fields.

[0045] The above content is only to illustrate the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention fall within the protection scope of the claims of the present invention.

Claims

1. A frequency division duplex balanced low noise amplifier based on a bridge, characterized in that: It includes bridge A and bridge B, both bridge A and bridge B are dual-frequency bridges, port P1 of bridge A receives signals, port P4 is connected to a load, ports P2 and P3 are respectively connected to the input of a low-noise amplifier, the output of the low-noise amplifier is respectively connected to ports P5 and P8 of bridge B, port P6 outputs a frequency f1 signal, port P7 can output a frequency f2 signal or port P6 outputs a frequency f2 signal, port P7 outputs a frequency f1 signal; the output ports of bridge A are in opposite phases, and the output ports of bridge B are in the same phase.

2. A frequency division duplex balanced low noise amplifier based on a bridge according to claim 1, characterized in that: The operating frequencies of bridge A are f1 and f2. Four quarter-wavelength microstrip lines are loaded by a 90-degree coupler to realize dual-frequency 90-degree and -90-degree phase difference coupling. Two half-wavelength @f0 microstrip lines TL1 are connected with two half-wavelength @f0 microstrip lines TL3 to form a traditional 90-degree bridge. Four quarter-wavelength @f0 microstrip lines TL2 cross to connect port P1 with port P3 and port P2 with port P4. At the same time, port P1 is connected to port P2 and port P4 is connected to port P3 through half-wavelength @f0 microstrip line TL1, and port P1 is connected to port P4 and port P2 is connected to port P3 through half-wavelength @f0 microstrip line TL3.

3. A frequency division duplex balanced low noise amplifier based on a bridge according to claim 2, characterized in that: When the input port is port P1 and the circuit operates at frequencies f1 and f2, at the operating frequency f1, there is a 90-degree phase difference between the through port and the coupled port of bridge A, and at the operating frequency f2, there is a -90-degree phase difference between the through port and the coupled port of bridge A, or at the operating frequency f1, there is a -90-degree phase difference between the through port and the coupled port of bridge A, and at the operating frequency f2, there is a 90-degree phase difference between the through port and the coupled port of bridge A.

4. A bridge-based frequency division duplex balanced low noise amplifier according to claim 2, characterized in that: f1 and f2 as well as the bandwidth of the working frequency band can be controlled by adjusting the impedance of three microstrip lines: half wavelength @ f0 microstrip line TL1, quarter wavelength @ f0 microstrip line TL2, and half wavelength @ f0 microstrip line TL3.

5. A frequency division duplex balanced low noise amplifier based on a bridge according to claim 1, characterized in that: Bridge B is composed of a 90-degree coupler loaded with four quarter-wavelength open branches to achieve dual-frequency 90-degree phase difference coupling, where two quarter-wavelength @f0 microstrip lines TL2 and two quarter-wavelength @f0 microstrip lines TL3 are connected as shown in the figure to form a traditional 90-degree bridge, and four quarter-wavelength @f0 microstrip lines TL1 are loaded between the input port and the quarter-wavelength @f0 microstrip lines TL2 and the quarter-wavelength @f0 microstrip lines TL3.

6. A bridge-based frequency division duplex balanced low noise amplifier according to claim 5, characterized in that: Bridge B is a dual-frequency bridge with operating frequencies of f1 and f2. At operating frequency f1, there is a 90-degree phase difference between the through port and the coupled port of bridge B. At operating frequency f2, there is a 90-degree phase difference between the through port and the coupled port of bridge B.

7. A bridge-based frequency division duplex balanced low noise amplifier according to claim 1, characterized in that: When the port P1 receives a signal with a frequency of f1 & f2, the port P6 and the port P7 respectively output the f1 frequency signal and the f2 frequency signal or respectively output the f2 frequency signal and the f1 frequency signal.

8. The bridge-based frequency division duplex balanced low noise amplifier according to claim 1, characterized in that: The two operating frequencies of bridge A and bridge B are 1A With f 1B Same, f 2A With f 2B same.

9. A bridge-based frequency division duplex balanced low noise amplifier according to claim 1, characterized in that: The low noise amplifier adopts a two-stage transistor amplification circuit.

10. A radio frequency receiver, characterized in that: A frequency division duplex balanced low noise amplifier based on a bridge as described in any one of claims 1 to 9 is used.

Images