A bidirectional amplifier based on LMBA structure and three-coupled transformer

Abstract

The application belongs to the technical field of wireless communication, and relates to an amplifier of a radio frequency front end in a transceiving system, and particularly provides a bidirectional amplifier based on an LMBA structure and three coupled transformers, which is used to improve the PA efficiency of the bidirectional amplifier and reduce the LNA noise coefficient; the three coupled transformers are adopted, the replacement of switches is realized by using the impedance characteristic change of a transistor, compared with the bidirectional amplifier structure with switches, the bidirectional amplifier has lower insertion loss in the radio frequency field, the improvement of the PA efficiency of the bidirectional amplifier and the reduction of the LNA noise coefficient are realized; meanwhile, the PA adopts the LMBA structure, the bidirectional amplification of signals is realized by using a BA path, compared with the previous bidirectional amplifier, the bidirectional amplifier has the characteristics of high efficiency in the power backoff interval.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology and relates to amplifiers in the radio frequency front-end of transceiver systems. Specifically, it provides a bidirectional amplifier based on an LMBA structure and a three-coupling transformer. Background Technology

[0002] With the rapid development of modern communication technology, the radio frequency (RF) front-end, as the core component of a transceiver system, directly determines the quality of the entire system. Amplifiers, as the core component of the RF front-end, naturally face higher performance requirements. RF amplifiers are classified into power amplifiers (PAs) and low-noise amplifiers (LNAs) based on their transmitting or receiving functions. The PA, as the core of the transmitter, can consume up to one-third of the system's power. The LNA, as the first active device in the receiver, largely determines the system's noise figure. Therefore, improving PA efficiency and reducing LNA noise are of significant research value.

[0003] Standalone transceiver amplifier circuits typically occupy a large area, especially in systems like phased arrays that require simultaneous receiving and transmitting functions. Therefore, bidirectional amplifiers integrating switches and both transmit and receive amplifiers have become a research focus. Bidirectional amplifiers allow the transmit and receive links to share up-conversion and down-conversion circuits, resulting in better integration, reduced system area, and lower RF front-end costs. A basic bidirectional amplifier (BDA) is as follows: Figure 1 As shown, a simple switch is used to switch between the power amplifier and the low-noise amplifier. When the single-pole double-throw switch is placed in the transmit path, the amplifier operates in PA mode; when the single-pole double-throw switch is placed in the receive path, the amplifier operates in LNA mode. However, when amplifying peak-to-average power ratio (PA) signals, the low-power output efficiency of the basic bidirectional amplifier (BDA) is low and cannot meet the application requirements. Summary of the Invention

[0004] The purpose of this invention is to provide a bidirectional amplifier based on an LMBA structure and a triple-coupled transformer, which improves the efficiency of the bidirectional amplifier PA while reducing the noise figure of the LNA. This invention uses a triple-coupled transformer and utilizes the impedance characteristics of the transistor to replace the switch. Compared with the bidirectional amplifier structure with a switch, it has lower insertion loss in the radio frequency field, thus improving the efficiency of the bidirectional amplifier PA and reducing the noise figure of the LNA. At the same time, the PA adopts an LMBA structure and uses the BA circuit to achieve bidirectional signal amplification, which has the characteristic of high efficiency in the power back-off range compared with the previous bidirectional amplifier.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A bidirectional amplifier based on an LMBA structure and three-coupling transformers includes: a power divider, quadrature couplers Coupler1 and Coupler2, a CA path, a BA1 path, a BA2 path, an LNA1 path, an LNA2 path, and three-coupling transformers Transformer1 to Transformer4; characterized in that:

[0007] The BA1 path and the LNA1 path form the first bidirectional balanced branch, and the BA2 path and the LNA2 path form the second bidirectional balanced branch. The first bidirectional balanced branch and the second bidirectional balanced branch use the same circuit (the circuit structure and parameters are exactly the same).

[0008] The input terminal of the power divider serves as the input terminal for PA mode and the output terminal for LNA mode. One output of the power divider is connected to the CA path, and the output of the CA path is connected to the isolation terminal of the quadrature coupler Coupler 2. The other output of the power divider is connected to the input terminal of the quadrature coupler Coupler 1. The quadrature terminals (through and coupling terminals) of the quadrature coupler Coupler 1 are respectively connected to the first bidirectional balanced branch and the second bidirectional balanced branch through the three-coupling transformer Transformer 1 and the three-coupling transformer Transformer 2. The first bidirectional balanced branch and the second bidirectional balanced branch are then connected to the quadrature terminals (through and coupling terminals) of the quadrature coupler Coupler 2 through the three-coupling transformer Transformer 3 and the three-coupling transformer Transformer 4. The isolation terminal of the quadrature coupler Coupler 1 is connected to the isolation resistor to ground, and the input terminal of the quadrature coupler Coupler 2 is connected to the transceiver antenna.

[0009] Furthermore, the CA circuit includes: a driver amplifier DA and a power amplifier CA connected in series, the input terminal of the driver amplifier DA being connected to the output terminal of the power divider through a matching transformer, and the output terminal of the power amplifier CA being connected to the isolation terminal of the quadrature coupler Coupler2 through a matching transformer.

[0010] Furthermore, in the first bidirectional balanced branch, BA1 includes a driver amplifier DA and a power amplifier BA1, and LNA1 includes a driver amplifier DA and a low-noise amplifier LNA1. In BA1, the driver amplifier DA and the power amplifier BA1 are connected in series. The input terminal of the driver amplifier DA in BA1 is connected to the third-stage coil of the three-coupling transformer Transformer 1, and the output terminal of the power amplifier BA1 in BA1 is connected to the third-stage coil of the three-coupling transformer Transformer 3. In LNA1, the low-noise amplifier LNA1 is connected in series with the driver amplifier DA. The input terminal of the low-noise amplifier LNA1 in LNA1 is connected to the primary coil of the three-coupling transformer Transformer 3, and the output terminal of the driver amplifier DA in LNA1 is connected to the primary coil of the three-coupling transformer Transformer 1. The secondary coil of the three-coupling transformer Transformer 1 is connected to the through terminal of the quadrature coupler Coupler 1, and the secondary coil of the three-coupling transformer Transformer 3 is connected to the coupling terminal of the quadrature coupler Coupler 2.

[0011] Furthermore, in the second bidirectional balanced branch, BA2 includes a driver amplifier DA and a power amplifier BA2, and LNA2 includes a driver amplifier DA and a low-noise amplifier LNA2. In BA2, the driver amplifier DA and the power amplifier BA2 are connected in series. The input terminal of the driver amplifier DA in BA2 is connected to the third-stage coil of the triple-coupled transformer Transformer 2, and the output terminal of the power amplifier BA2 in BA2 is connected to the third-stage coil of the triple-coupled transformer Transformer 4. In LNA2, the low-noise amplifier LNA2 is connected in series with the driver amplifier DA. The input terminal of the low-noise amplifier LNA2 in LNA2 is connected to the primary coil of the triple-coupled transformer Transformer 4, and the output terminal of the driver amplifier DA in LNA2 is connected to the primary coil of the triple-coupled transformer Transformer 2. The secondary coil of the triple-coupled transformer Transformer 2 is connected to the coupling terminal of the quadrature coupler Coupler 1, and the secondary coil of the triple-coupled transformer Transformer 4 is connected to the through terminal of the quadrature coupler Coupler 2.

[0012] Furthermore, when the bidirectional amplifier operates in PA mode, both LNA1 and LNA2 are biased to zero, BA1 and BA2 are biased in Class-AB mode, and CA is biased in Class-C mode.

[0013] Furthermore, when the bidirectional amplifier operates in LNA mode, the CA, BA1, and BA2 paths are all biased to zero, while the LNA1 and LNA2 paths are biased in Class-A mode.

[0014] Based on the above technical solution, the beneficial effects of the present invention are as follows:

[0015] This invention provides a bidirectional amplifier based on an LMBA structure and a triple-coupled transformer, which achieves bidirectional signal amplification through the LMBA architecture and triple-coupled amplifier. First, by utilizing the LMBA structure, bidirectional signal amplification is achieved on the LMBA architecture, resulting in a significant improvement in PA efficiency compared to traditional bidirectional amplifiers. Second, by utilizing the triple-coupled transformer structure and the impedance change of the transistor, the on / off control of the circuit is achieved. Compared to traditional amplifiers, there is no constraint from the switch, resulting in a significant improvement in the efficiency, noise figure, and other characteristics of the bidirectional amplifier in the radio frequency field.

[0016] In summary, this invention employs a switchless current branch control structure, eliminating the performance degradation caused by switching in traditional bidirectional amplifiers. It balances the high efficiency of a power amplifier (PA) with the low noise figure of an low-noise amplifier (LNA). In PA mode, it exhibits high efficiency in the backoff interval, expanding the application scenarios of bidirectional amplifiers and making it possible to use bidirectional amplifiers in peak-to-average power ratio (PAPR) signal transmission scenarios. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a basic bidirectional amplifier (BDA).

[0018] Figure 2 This is a schematic diagram of a load-modulated balanced amplifier (LMBA).

[0019] Figure 3 This is a model diagram of the coupler in a load-modulated balanced amplifier.

[0020] Figure 4 This is a model diagram of a three-coupled transformer.

[0021] Figure 5 This is a π-shaped model diagram of an integrated inductor.

[0022] Figure 6 This is a simplified model diagram of an integrated inductor.

[0023] Figure 7 This is a simplified model diagram of a three-coupled transformer.

[0024] Figure 8 This is a schematic diagram of the bidirectional amplifier based on the LMBA structure and a three-coupled transformer provided by the present invention.

[0025] Figure 9 The schematic diagram of the PA mode operation of the bidirectional amplifier based on LMBA structure and three-coupled transformer provided by this invention.

[0026] Figure 10The current curves of the BA and CA paths in the bidirectional amplifier based on the LMBA structure and a three-coupled transformer provided by this invention are shown.

[0027] Figure 11 The impedance curves of the BA and CA paths in the bidirectional amplifier based on the LMBA structure and three-coupled transformer provided by this invention are shown.

[0028] Figure 12 The PA mode gain curve of the bidirectional amplifier based on LMBA structure and three-coupled transformer provided by this invention.

[0029] Figure 13 The PA mode PAE curve of the bidirectional amplifier based on LMBA structure and three coupling transformer provided by the present invention.

[0030] Figure 14 The diagram shows the working principle of the LNA mode of the bidirectional amplifier based on the LMBA structure and three coupling transformers provided by this invention.

[0031] Figure 15 The LNA mode gain curve of the bidirectional amplifier based on the LMBA structure and three coupling transformers provided by this invention.

[0032] Figure 16 The LNA mode PAE curve of the bidirectional amplifier based on LMBA structure and three coupling transformer provided by the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0034] This invention proposes a bidirectional amplifier based on an LMBA structure and a three-coupled transformer, which can operate in PA mode and LNA mode respectively.

[0035] In terms of working principle:

[0036] 1. Load-modulated balanced amplifier (LMBA);

[0037] Load-modulated balanced amplifier (LMBA) such as Figure 2 As shown, the LMBA mainly consists of a balanced amplifier (BA), a carrier amplifier (CA), and a quadrature coupler; the quadrature coupler plays a key role in the LMBA structure, and the coupler model is as follows. Figure 3 As shown, an excitation is applied to port 1 of the coupler. Assuming that the remaining ports are all connected to a load impedance Z0, the voltages at the remaining ports are as follows after parity-modulus analysis:

[0038]

[0039] in, Z 0e and Z 0o θ represents the characteristic impedances of the even mode and odd mode, respectively, and θ is the electrical length of the coupler.

[0040] The impedance matrix of the coupler is:

[0041]

[0042] in,

[0043] When the length of the coupler is λ / 4, θ = 90°. The voltage amplitudes at the coupling end and the through end are equal, with a phase difference of 90°; therefore, the impedance matrix of the quadrature coupler is:

[0044]

[0045] Let the current I in the BA circuit be... ba1 =-i ba1 and I ba2 =-j×i ba2 If the CA circuit current I ca Relative to I ba1 The phase shift is α, i.e., I ca =-i ca e jα Substituting this into the impedance matrix of the orthogonal coupler, we can obtain:

[0046]

[0047] Therefore, the impedance seen by the CA circuit is a fixed value and does not change with the current; the impedance seen by the BA circuit changes with the ratio of the currents in the CA and BA circuits. If I ca Relative to I ba1 If the phase shift is α = 0 / π, then the impedance seen by the BA circuit is the pure real part; that is, the load-modulated balanced amplifier (LMBA) can modulate the impedance of the BA circuit by controlling the magnitude and phase of the currents in the CA and BA circuits.

[0048] 2. Three-coupling transformer;

[0049] Inductive coupling plays a crucial role in millimeter-wave circuits and systems. The key focus of inductive coupling is the coupling coefficient and the coil inductance. The coupling process involves changes in the self-inductance and mutual inductance currents between inductors.

[0050] like Figure 4The model shown is a three-coupling transformer, where LP is the primary coil, LS is the secondary coil, LT is the tertiary coil, and k1, k2, and k3 are the coupling coefficients between LP and LS, LS and LT, and LP and LT, respectively.

[0051] like Figure 5 The diagram presents a relatively accurate π-shaped model of an integrated inductor, where L is the coil inductance, Rs is the coil loss, Cx and Cp are the parasitic capacitances of the coil, and Csub and Rsub are the parasitic capacitance and inductance of the substrate. Since the operating frequency is lower than the coil's self-resonant frequency, and the substrate parasitic parameters have little impact on the coil model, the circuit can be simplified. The simplified integrated inductor model is shown below. Figure 6 As shown; based on this, the model of the three-coupled transformer is simplified as follows. Figure 7 As shown, L1 to L3 are the inductances of the primary, secondary, and tertiary coils, respectively, and Rs1 to Rs3 are the losses of the primary, secondary, and tertiary coils, respectively. The primary coil is connected to the external input V1, and the secondary and tertiary coils are connected to transistors. Taking the secondary coil as an example, the equivalent resistance is small when the transistor is on and large when the transistor is off, approximately equivalent to the series connection of the equivalent resistance r2 and the equivalent switch sw2. Similarly, for the tertiary coil, the transistor connected to it is approximately equivalent to the series connection of the equivalent resistance r3 and the equivalent switch sw3.

[0052] Assuming the losses of the primary, secondary, and tertiary coils are the same (Rs1 = Rs2 = Rs3 = Rs), then the relationship between voltage, current, and impedance of the three-coupled transformer is:

[0053]

[0054] Where V1, V2, and V3 represent the port voltages of the primary, secondary, and tertiary coils, and I1, I2, and I3 represent the port currents of the primary, secondary, and tertiary coils; ω represents 2πf, where f is the operating frequency; M12 represents the mutual inductance between the primary and secondary coils; M23 represents the mutual inductance between the secondary and tertiary coils; and M13 represents the mutual inductance between the primary and tertiary coils.

[0055] If sw3 is disconnected, then I3 is 0 and V3 is 0:

[0056]

[0057] 0=jωM13×I1+jωM23×I2

[0058] Since I1 and I2 are not 0, it is not difficult to conclude that M13 and M23 are also 0. Therefore, k2 and k3 are 0, and the three-coupled transformer degenerates into a two-coupled transformer, represented as:

[0059]

[0060] Based on this, the present invention proposes a bidirectional amplifier by combining a load-modulated balanced amplifier (LMBA) and a three-coupling transformer, such as... Figure 8 As shown, it specifically includes: a power divider, quadrature couplers Coupler1 and Coupler2, CA path, BA1 path, BA2 path, LNA1 path, LNA2 path, and three-coupling transformers Transformer1 to Transformer4; BA1 path and LNA1 path form the first bidirectional balanced branch, and BA2 path and LNA2 path form the second bidirectional balanced branch. The first and second bidirectional balanced branches use the same circuit (the circuit structure and parameters are completely identical); wherein: the input terminal of the power divider serves as the input terminal for PA mode and the output terminal for LNA mode, one output of the power divider is connected to CA path, and the output of CA path is connected to the isolation terminal of quadrature coupler Coupler2; the other... One output is connected to the input of the quadrature coupler Coupler1. The quadrature terminals (through and coupling terminals) of the quadrature coupler Coupler1 are connected to the first bidirectional balanced branch and the second bidirectional balanced branch respectively through the three-coupling transformer Transformer1 and Transformer2. The first bidirectional balanced branch and the second bidirectional balanced branch are then connected to the quadrature terminals (through and coupling terminals) of the quadrature coupler Coupler2 respectively through the three-coupling transformer Transformer3 and Transformer4. The isolation terminal of the quadrature coupler Coupler1 is connected to the isolation resistor to ground, and the input terminal of the quadrature coupler Coupler2 is connected to the transmit and receive antenna.

[0061] Furthermore, the CA circuit includes: a driver amplifier DA and a power amplifier CA connected in series, the input terminal of the driver amplifier DA being connected to the output terminal of the power divider through a matching transformer, and the output terminal of the power amplifier CA being connected to the isolation terminal of the quadrature coupler Coupler2 through a matching transformer.

[0062] Furthermore, in the first bidirectional balanced branch, BA1 includes a driver amplifier DA and a power amplifier BA1, and LNA1 includes a driver amplifier DA and a low-noise amplifier LNA1. In BA1, the driver amplifier DA and the power amplifier BA1 are connected in series. The input terminal of the driver amplifier DA in BA1 is connected to the third-stage coil of the three-coupling transformer Transformer 1, and the output terminal of the power amplifier BA1 in BA1 is connected to the third-stage coil of the three-coupling transformer Transformer 3. In LNA1, the low-noise amplifier LNA1 and the driver amplifier DA are connected in series. The input terminal of the low-noise amplifier LNA1 in LNA1 is connected to the primary coil of the three-coupling transformer Transformer 3, and the output terminal of the driver amplifier DA in LNA1 is connected to the primary coil of the three-coupling transformer Transformer 1. The secondary coil of the three-coupling transformer Transformer 1 is connected to the through terminal of the quadrature coupler Coupler 1, and the secondary coil of the three-coupling transformer Transformer 3 is connected to the coupling terminal of the quadrature coupler Coupler 2.

[0063] Similarly, in the second bidirectional balanced branch, BA2 includes a driver amplifier DA and a power amplifier BA2, and LNA2 includes a driver amplifier DA and a low-noise amplifier LNA2. In BA2, the driver amplifier DA and the power amplifier BA2 are connected in series. The input terminal of the driver amplifier DA in BA2 is connected to the third-stage coil of the triple-coupled transformer Transformer 2, and the output terminal of the power amplifier BA2 in BA2 is connected to the third-stage coil of the triple-coupled transformer Transformer 4. In LNA2, the low-noise amplifier LNA2 and the driver amplifier DA are connected in series. The input terminal of the low-noise amplifier LNA2 in LNA2 is connected to the primary coil of the triple-coupled transformer Transformer 4, and the output terminal of the driver amplifier DA in LNA2 is connected to the primary coil of the triple-coupled transformer Transformer 2. The secondary coil of the triple-coupled transformer Transformer 2 is connected to the coupling terminal of the quadrature coupler Coupler 1, and the secondary coil of the triple-coupled transformer Transformer 4 is connected to the through terminal of the quadrature coupler Coupler 2.

[0064] like Figure 9 As shown, when the circuit is working in PA mode: the LNA circuit bias is set to zero, and the input resistance of the LNA transistor is a large impedance. According to the analysis of the three-coupled transformer, the three-coupled transformer degenerates into a two-coupled transformer. The coupling coefficient between the LNA coil and the primary coil is very low, and the power is mainly propagated through the PA circuit. In PA mode, the circuit works as LMBA.

[0065] The input signal first enters the power divider, one path goes to the CA path, and the other path goes to the input of the quadrature coupler Coupler1. Since the CA path is biased in Class-C, it does not work for small signal input power. The power entering the quadrature coupler Coupler1 is split into two signals with a 90° phase difference, which enter BA1 and BA2 from the two outputs respectively. The isolation terminal of the quadrature coupler Coupler1 is connected to a 50Ω impedance. The signals entering Bas (BA1 and BA2) are matched by a two-coupled transformer degenerated from a three-coupled transformer, amplified by the DA and BA amplifiers, and finally reach the output of the quadrature coupler Coupler2. Since the two BA paths are exactly 90° out of phase, the output power is superimposed in phase at the antenna end and canceled out in phase at the CA end. All the output power enters the antenna end and does not flow into the isolation terminal.

[0066] As the input signal gradually increases, the BA amplifier first reaches saturation, and then the CA amplifier will turn on. The CA signal, after being matched by the transformer and amplified by the CA amplifier, flows into the isolation port of the output quadrature coupler. According to the load modulation effect described above, the isolation port impedance of the quadrature coupler Coupler1 is a constant value and equal to the characteristic impedance of the quadrature coupler. The port impedances of the quadrature couplers connected to the two BAs paths are controlled by the magnitudes of the CA and BA currents and their phase difference α, specifically as follows:

[0067]

[0068] Therefore, by setting appropriate current magnitude ratios and phase differences, the impedance of the BA port can be the real part that decreases as the current in the CA increases, thus achieving load modulation.

[0069] like Figure 10 , Figure 11 The figures show the changes in current and port impedance of the BA and CA circuits, respectively. The blue area represents the low-power region, where only the BA circuit is active. The red area represents the power fallback region, where the CA circuit is active and the port impedance of the BA circuit decreases as the current in the CA circuit increases. At the same time, the current in the BA circuit also increases, leading to an expansion of the output power of the BA circuit. The green area represents the saturation region, where both the BA and CA circuit amplifiers have reached their saturation output current and saturation output power.

[0070] like Figure 12 , Figure 13 The figures show the gain curve and PAE curve of the bidirectional amplifier in PA mode, respectively. As can be seen from the figures, the bidirectional amplifier in PA mode has a relatively flat gain curve and a high PAE in the 6dB back-off range.

[0071] like Figure 14As shown, when the circuit is working in LNA mode: the PA circuit amplifier bias is set to zero, and the circuit structure is relatively simple at this time; the received signal enters from the antenna port, is split into two signals with a 90° phase difference by the quadrature coupler, and after matching and LNA amplification, it is combined by the quadrature coupler; at the power divider position, since the CA circuit is not working, the corresponding port is equivalent to a large impedance, so that the signal can pass through the power divider with almost no loss.

[0072] like Figure 15 , Figure 16 The figures show the noise figure curve and S21 curve of the bidirectional amplifier in LNA mode, respectively. As can be seen from the figure, the noise figure of the bidirectional amplifier in LNA mode is low, about 4.5, and the S21 curve is good.

[0073] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. A bidirectional amplifier based on an LMBA structure and a three-coupling transformer, comprising: The power divider, quadrature couplers Coupler1 and Coupler2, CA path, BA1 path, BA2 path, LNA1 path, LNA2 path, and three-coupling transformers Transformer1 to Transformer4 are characterized by: The BA1 path and the LNA1 path form the first bidirectional balanced branch, and the BA2 path and the LNA2 path form the second bidirectional balanced branch. The first bidirectional balanced branch and the second bidirectional balanced branch use the same circuit. The input terminal of the power divider serves as the input terminal for PA mode and the output terminal for LNA mode. One output of the power divider is connected to the CA path, and the output of the CA path is connected to the isolation terminal of the quadrature coupler Coupler 2. The other output of the power divider is connected to the input terminal of the quadrature coupler Coupler 1. The through terminal and the coupling terminal of the quadrature coupler Coupler 1 are respectively connected to the first bidirectional balanced branch and the second bidirectional balanced branch through the three-coupling transformer Transformer 1 and the three-coupling transformer Transformer 2. The first bidirectional balanced branch and the second bidirectional balanced branch are then connected to the coupling terminal and the through terminal of the quadrature coupler Coupler 2 through the three-coupling transformer Transformer 3 and the three-coupling transformer Transformer 4. The isolation terminal of the quadrature coupler Coupler 1 is connected to the isolation resistor to ground, and the input terminal of the quadrature coupler Coupler 2 is connected to the transceiver antenna. In the first bidirectional balanced branch, BA1 includes a driver amplifier DA and a power amplifier BA1, and LNA1 includes a driver amplifier DA and a low-noise amplifier LNA1. In BA1, the driver amplifier DA and the power amplifier BA1 are connected in series. The input terminal of the driver amplifier DA in BA1 is connected to the third-stage coil of a three-coupling transformer Transformer 1, and the output terminal of the power amplifier BA1 in BA1 is connected to the third-stage coil of a three-coupling transformer Transformer 3. In LNA1, the low-noise amplifier LNA1 and the driver amplifier DA are connected in series. The input terminal of the low-noise amplifier LNA1 in LNA1 is connected to the primary coil of a three-coupling transformer Transformer 3, and the output terminal of the driver amplifier DA in LNA1 is connected to the primary coil of a three-coupling transformer Transformer 1. The secondary coil of the three-coupling transformer Transformer 1 is connected to the through terminal of a quadrature coupler Coupler 1, and the secondary coil of the three-coupling transformer Transformer 3 is connected to the coupling terminal of a quadrature coupler Coupler 2. In the second bidirectional balanced branch, BA2 includes a driver amplifier DA and a power amplifier BA2, and LNA2 includes a driver amplifier DA and a low-noise amplifier LNA2. In BA2, the driver amplifier DA and the power amplifier BA2 are connected in series. The input terminal of the driver amplifier DA in BA2 is connected to the third-stage coil of the triple-coupled transformer Transformer 2, and the output terminal of the power amplifier BA2 in BA2 is connected to the third-stage coil of the triple-coupled transformer Transformer 4. In LNA2, the low-noise amplifier LNA2 is connected in series with the driver amplifier DA. The input terminal of the low-noise amplifier LNA2 in LNA2 is connected to the primary coil of the triple-coupled transformer Transformer 4, and the output terminal of the driver amplifier DA in LNA2 is connected to the primary coil of the triple-coupled transformer Transformer 2. The secondary coil of the triple-coupled transformer Transformer 2 is connected to the coupling terminal of the quadrature coupler Coupler 1, and the secondary coil of the triple-coupled transformer Transformer 4 is connected to the through terminal of the quadrature coupler Coupler 2.

2. The bidirectional amplifier based on LMBA structure and three-coupling transformer according to claim 1, characterized in that, The CA circuit includes: a driver amplifier DA and a power amplifier CA connected in series. The input terminal of the driver amplifier DA is connected to the output terminal of the power divider through a matching transformer, and the output terminal of the power amplifier CA is connected to the isolation terminal of the quadrature coupler Coupler2 through a matching transformer.

3. The bidirectional amplifier based on LMBA structure and three-coupling transformer according to claim 1, characterized in that, When the bidirectional amplifier operates in PA mode, both LNA1 and LNA2 are biased to zero, BA1 and BA2 are biased in Class-AB mode, and CA is biased in Class-C mode.

4. The bidirectional amplifier based on LMBA structure and three-coupled transformer according to claim 1, characterized in that, When the bidirectional amplifier operates in LNA mode, the CA, BA1, and BA2 paths are all biased to zero, while the LNA1 and LNA2 paths are biased in Class-A mode.

Images