A Millimeter-Wave Load Modulation Balanced Amplifier Based on Variable Cross-Coupled Pairs

Abstract

The present invention discloses a millimeter-wave load modulation balanced amplifier based on a variable cross-coupled pair, which is characterized by comprising an adaptive bias circuit, a first balanced-end amplifier module, a second balanced-end amplifier module, a control-end amplifier module, a first driver amplifier module, a second driver amplifier module, a third driver amplifier module, a variable cross-coupled pair, a resistor R5, a resistor R6, a differential 90° coupler Q1, a differential 90° coupler Q2 and a differential 90° coupler Q3; compared with only using the adaptive bias technology, the combination of the structure of the variable cross-coupled pair proposed by the present invention and the adaptive bias can improve the overall linearity of the load modulation balanced amplifier and will not deteriorate the efficiency in the power back-off region.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and specifically includes a millimeter-wave load modulation balanced amplifier based on a variable cross-coupled pair. Background Art

[0002] With the formation of the fifth-generation wireless communication system, the requirement for data rate is getting higher and higher. Due to the scarcity of spectrum resources, low-latency and high-capacity wireless connections require advanced modulation schemes to improve spectrum utilization. However, these complexly modulated radio waves have a high peak-to-average power ratio, resulting in a significant reduction in the efficiency of traditional power amplifiers. To improve the efficiency of power amplifiers in amplifying signals with a high peak-to-average power ratio, a load modulation balanced amplifier has been proposed recently. The load modulation balanced amplifier includes a balanced-end amplifier and a control-end amplifier, and realizes load modulation by changing the ratio of the output power of the control-end amplifier to the output power of the balanced-end amplifier. The balanced-end amplifier operates in class C mode, and the control-end amplifier operates in class AB mode.

[0003] Since the gain difference between class AB amplifiers and class C amplifiers in the millimeter-wave band is large, and the gain of class C amplifiers is very low, the overall gain of the amplifier will decrease sharply with the increase of the input power after the balanced-end amplifier is turned on, so its linearity is severely deteriorated, which limits the application of the load modulation balanced amplifier in the millimeter-wave band. Summary of the Invention

[0004] Aiming at the above deficiencies in the prior art, a millimeter-wave load modulation balanced amplifier based on a variable cross-coupled pair provided by the present invention solves the problem that the large gain difference between class AB amplifiers and class C amplifiers in the millimeter-wave band limits the application of the load modulation balanced amplifier in the millimeter-wave band.

[0005] To achieve the above invention purpose, the technical solution adopted by the present invention is: a millimeter-wave load modulation balanced amplifier based on a variable cross-coupled pair, including an adaptive bias circuit, a first balanced-end amplifier module, a second balanced-end amplifier module, a control-end amplifier module, a first driver amplifier module, a second driver amplifier module, a third driver amplifier module, a variable cross-coupled pair, a resistor R5, a resistor R6, a differential 90° coupler Q1, a differential 90° coupler Q2, and a differential 90° coupler Q3;

[0006] The input terminal of the adaptive bias circuit and the third input terminal of the differential 90° coupler Q1 serve as the input terminals of the amplifier; one end of the isolation terminal of the differential 90° coupler Q1 is connected to the other end of the isolation terminal of the differential 90° coupler Q1 through the resistor R5; one end of the through terminal of the differential 90° coupler Q1 is connected to the first input terminal of the differential 90° coupler Q2; the other end of the through terminal of the differential 90° coupler Q1 is connected to the second input terminal of the differential 90° coupler Q2; one end of the isolation terminal of the differential 90° coupler Q2 is connected to the other end of the isolation terminal of the differential 90° coupler Q2 through the resistor R6;; the third output terminal of the differential 90° coupler Q1 is connected to the input terminal of the third drive amplifier module; the output terminal of the third drive amplifier module is connected to the input terminal of the control terminal amplifier module; one end of the coupled terminal of the differential 90° coupler Q2 is connected to the first input terminal of the first drive amplifier module; the other end of the coupled terminal of the differential 90° coupler Q2 is connected to the second input terminal of the first drive amplifier module; one end of the through terminal of the differential 90° coupler Q2 is connected to the first input terminal of the second drive amplifier module; the other end of the through terminal of the differential 90° coupler Q2 is connected to the second input terminal of the second drive amplifier module; the output terminal of the first drive amplifier module is connected to the input terminal of the first balanced terminal amplifier module; the output terminal of the second drive amplifier module is connected to the input terminal of the second balanced terminal amplifier module; the first output terminal and the second output terminal of the first balanced terminal amplifier module are connected to one end and the other end of the through terminal of the differential 90° coupler Q3; the first output terminal of the second balanced terminal amplifier module is connected to one end of the coupled terminal of the differential 90° coupler Q3; the second output terminal of the second balanced terminal amplifier module is connected to the other end of the coupled terminal of the differential 90° coupler Q3; the output terminal of the control terminal amplifier module is connected to the isolation terminal of the differential 90° coupler Q3; the output terminal of the differential 90° coupler Q3 serves as the output terminal of the millimeter-wave load modulation balanced amplifier based on the variable cross-coupled pair.

[0007] Further, the adaptive bias circuit includes transistor M4, resistor R LP , capacitor C LP , transistor M 4n , transistor M 5n , transistor M 6n , transistor M 4p , transistor M 5p , transistor M 6p , resistor R1, resistor R2, capacitor C1, capacitor C2, capacitor C3 and capacitor C4;

[0008] One end of the capacitor C1 serves as the input end of the adaptive bias circuit; the other end of the capacitor C1 is connected to one end of the resistor R1 and the base of the transistor M4; the other end of the resistor R1 is connected to the detection voltage; the emitter of the transistor M4 is grounded; the collector of the transistor M4 is connected to one end of the resistor R LP ; one end of the capacitor C LP ; one end of the transistor M 4n ; the base of the transistor M 5n ; the base of the transistor M 6n ; the base of the transistor M 4p ; the base of the transistor M 5p ; the base of the transistor M 6p ; the base of the transistor M LP ; the other end of the resistor R is connected to the 1V power supply and the other end of the capacitor C LP ; the collector of the transistor M 4p is connected to the bias voltage V cnt1 ; the collector of the transistor M 5p is connected to the bias voltage V cnt1 ; the collector of the transistor M 6p is connected to the bias voltage V cnt2 ; the collector of the transistor M 4p ; the emitter is connected to one end of the capacitor C4, one end of the resistor R2 and the collector of the transistor M 4n ; the other end of the capacitor C4 is grounded; the emitter of the transistor M 4n is grounded; the emitter of the transistor M 5p ; the emitter is connected to one end of the capacitor C3, one end of the resistor R3 and the collector of the transistor M 5n ; the other end of the capacitor C3 is grounded; the emitter of the transistor M 5n is grounded; the emitter of the transistor M 6p ; the emitter is connected to one end of the capacitor C2, one end of the resistor R4 and the collector of the transistor M 6n ; the other end of the capacitor C2 is grounded; the emitter of the transistor M 6n is grounded; the other end of the resistor R2 serves as the first output end of the adaptive bias circuit; the other end of the resistor R3 serves as the second output end of the adaptive bias circuit; the other end of the resistor R4 serves as the third output end of the adaptive bias circuit.

[0009] Further, the first drive amplifier module includes a transformer Xfrm1 and a drive amplifier DA1; the primary side of the transformer Xfrm1 is the input end of the first drive amplifier module; the first end of the secondary side of the transformer Xfrm1 is connected to the first input end of the drive amplifier DA1; the second end of the secondary side of the transformer Xfrm1 is connected to the second input end of the drive amplifier DA1; the third end of the secondary side of the transformer Xfrm1 is connected to the output end of the adaptive bias circuit; the first output end and the second output end of the drive amplifier DA1 are connected to the first balanced-end amplifier module.

[0010] Further, the second drive amplifier module includes a transformer Xfrm2 and a drive amplifier DA2; the primary side of the transformer Xfrm2 is the input end of the second drive amplifier module; the first end of the secondary side of the transformer Xfrm2 is connected to the first input end of the drive amplifier DA2; the second end of the secondary side of the transformer Xfrm2 is connected to the second input end of the drive amplifier DA2; the third end of the secondary side of the transformer Xfrm2 is connected to the output end of the adaptive bias circuit; the first output end and the second output end of the drive amplifier DA2 are connected to the second balanced-end amplifier module.

[0011] Further, the third drive amplifier module includes a transformer Xfrm3 and a drive amplifier DA3; the primary side of the transformer Xfrm3 is the input end of the third drive amplifier module; one end of the secondary side of the transformer Xfrm3 is connected to the first input end of the drive amplifier DA3; the other end of the secondary side of the transformer Xfrm3 is connected to the second input end of the drive amplifier DA3; the first output end and the second output end of the drive amplifier DA3 are connected to the variable cross-coupled pair.

[0012] Further, the first balanced-end amplifier module includes a balanced-end amplifier BA1, a transformer Xfmr4 and a transformer Xfmr7; the primary side of the transformer Xfmr4 is the input end of the first balanced amplifier module; the first end of the secondary side of the transformer Xfmr4 is connected to the first input end of the balanced-end amplifier BA1; the second end of the secondary side of the transformer Xfmr4 is connected to the second input end of the balanced-end amplifier BA1; the third end of the secondary side of the transformer Xfrm4 is connected to the output end of the adaptive bias circuit; the first output end of the balanced-end amplifier BA1 is connected to one end of the primary side of the transformer Xfmr7; the second output end of the balanced-end amplifier BA1 is connected to the other end of the primary side of the transformer Xfmr7; one end of the secondary side of the transformer Xfmr7 is connected to one end of the through-end of the differential 90° coupler Q3; the other end of the secondary side of the transformer Xfmr7 is connected to the other end of the through-end of the differential 90° coupler Q3.

[0013] Further, the second balanced-end amplifier module includes a balanced-end amplifier BA2, a transformer Xfmr5, and a transformer Xfmr8; the primary side of the transformer Xfmr5 is the input end of the second balanced amplifier module; the first end of the secondary side of the transformer Xfmr5 is connected to the first input end of the balanced-end amplifier BA2; the second end of the secondary side of the transformer Xfmr5 is connected to the second input end of the balanced-end amplifier BA2; the third end of the secondary side of the transformer Xfrm5 is connected to the output end of the adaptive bias circuit; the first output end of the balanced-end amplifier BA2 is connected to one end of the primary side of the transformer Xfmr8; the second output end of the balanced-end amplifier BA2 is connected to the other end of the primary side of the transformer Xfmr8; one end of the secondary side of the transformer Xfmr8 is connected to one end of the coupled end of the differential 90° coupler Q3; the other end of the secondary side of the transformer Xfmr8 is connected to the other end of the coupled end of the differential 90° coupler Q3.

[0014] Further, the variable cross-coupled pair includes a transistor M1, a transistor M2, and a transistor M3; the base-collector of the transistor M1 is connected to the second output end of the drive amplifier DA3, the collector of the transistor M2, and the control-end amplifier module; the base-collector of the transistor M2 is connected to the first output end of the drive amplifier DA3, the collector of the transistor M1, and the control-end amplifier module; the emitter of the transistor M1 is connected to the collector of the transistor M3 and the emitter of the transistor M2; the emitter of the transistor M3 is grounded; the base-collector of the transistor M3 is connected to the output end of the adaptive bias circuit.

[0015] Further, the control-end amplifier module includes a control-end amplifier CA, a transformer Xfmr6, and a transformer Xfmr9; the primary side of the transformer Xfmr6 serves as the input end of the control-end amplifier module; one end of the secondary side of the transformer Xfmr6 is connected to the first input end of the control-end amplifier CA; the other end of the secondary side of the transformer Xfmr6 is connected to the second input end of the control-end amplifier CA; the first output end of the control-end amplifier CA is connected to one end of the primary side of the transformer Xfmr9; the second output end of the control-end amplifier CA is connected to the other end of the primary side of the transformer Xfmr9; one end of the secondary side of the transformer Xfmr9 is connected to one end of the isolation end of the differential 90° coupler Q3 of the 90° coupler Q3; the other end of the secondary side of the transformer Xfmr9 is connected to the other end of the isolation end of the 90° coupler Q1.

[0016] The beneficial effects of the present invention are as follows: The structure of the variable cross-coupled pair proposed by the present invention makes the load impedance of the common-source amplifier increase with the increase of power, thereby compensating for the trend of the gain of the common-source amplifier to decrease with power, thus improving the linearity of the amplifier, and this technology will not deteriorate the efficiency in the power back-off area. Description of the Drawings

[0017] Figure 1 It is a structural diagram of the present invention;

[0018] Figure 2 Schematic diagram of an adaptive bias circuit;

[0019] Figure 3 Schematic diagram of an equivalent circuit of a variable cross-coupled pair;

[0020] Figure 4 Schematic diagram for improving the linearity of a variable cross-coupled pair;

[0021] Figure 5 Comparison chart of the linearity and power added efficiency of a load-modulated balanced amplifier with or without using a variable cross-coupled pair. Specific implementation manners

[0022] The specific implementation manners of the present invention will be described below to facilitate those skilled in the art of this technology to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation manners. For those ordinary skilled in the art of this technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are within the scope of protection.

[0023] As Figure 1 shown, a millimeter-wave load-modulated balanced amplifier based on a variable cross-coupled pair includes an adaptive bias circuit, a first balanced-terminal amplifier module, a second balanced-terminal amplifier module, a control-terminal amplifier module, a first driver amplifier module, a second driver amplifier module, a third driver amplifier module, a variable cross-coupled pair, a resistor R5, a resistor R6, a differential 90° coupler Q1, a differential 90° coupler Q2, and a differential 90° coupler Q3;

[0024] The input end of the adaptive bias circuit and the third input end of the differential 90° coupler Q1 serve as the input end of the amplifier; one end of the isolation end of the differential 90° coupler Q1 is connected to the other end of the isolation end of the differential 90° coupler Q1 through the resistor R5; one end of the through end of the differential 90° coupler Q1 is connected to the first input end of the differential 90° coupler Q2; the other end of the through end of the differential 90° coupler Q1 is connected to the second input end of the differential 90° coupler Q2; one end of the isolation end of the differential 90° coupler Q2 is connected to the other end of the isolation end of the differential 90° coupler Q2 through the resistor R6;; the third output end of the differential 90° coupler Q1 is connected to the input end of the third driver amplifier module; the output end of the third driver amplifier module is connected to the input end of the control end amplifier module; one end of the coupled end of the differential 90° coupler Q2 is connected to the first input end of the first driver amplifier module; the other end of the coupled end of the differential 90° coupler Q2 is connected to the second input end of the first driver amplifier module; one end of the through end of the differential 90° coupler Q2 is connected to the first input end of the second driver amplifier module; the other end of the through end of the differential 90° coupler Q2 is connected to the second input end of the second driver amplifier module; the output end of the first driver amplifier module is connected to the input end of the first balanced end amplifier module; the output end of the second driver amplifier module is connected to the input end of the second balanced end amplifier module; the first output end and the second output end of the first balanced end amplifier module are connected to one end and the other end of the through end of the differential 90° coupler Q3; the first output end of the second balanced end amplifier module is connected to one end of the coupled end of the differential 90° coupler Q3; the second output end of the second balanced end amplifier module is connected to the other end of the coupled end of the differential 90° coupler Q3; the output end of the control end amplifier module is connected to the isolation end of the differential 90° coupler Q3; the output end of the differential 90° coupler Q3 serves as the output end of the millimeter-wave load modulation balanced amplifier based on the variable cross-coupled pair.

[0025] The first driver amplifier module includes a transformer Xfrm1 and a driver amplifier DA1; the primary side of the transformer Xfrm1 is the input end of the first driver amplifier module; the first end of the secondary side of the transformer Xfrm1 is connected to the first input end of the driver amplifier DA1; the second end of the secondary side of the transformer Xfrm1 is connected to the second input end of the driver amplifier DA1; the third end of the secondary side of the transformer Xfrm1 is connected to the output end of the adaptive bias circuit; the first output end and the second output end of the driver amplifier DA1 are connected to the first balanced end amplifier module.

[0026] The second drive amplifier module includes a transformer Xfrm2 and a drive amplifier DA2; the primary side of the transformer Xfrm2 is the input end of the second drive amplifier module; the first end of the secondary side of the transformer Xfrm2 is connected to the first input end of the drive amplifier DA2; the second end of the secondary side of the transformer Xfrm2 is connected to the second input end of the drive amplifier DA2; the third end of the secondary side of the transformer Xfrm2 is connected to the output end of the adaptive bias circuit; the first output end and the second output end of the drive amplifier DA2 are connected to the second balanced-end amplifier module.

[0027] The third drive amplifier module includes a transformer Xfrm3 and a drive amplifier DA3; the primary side of the transformer Xfrm3 is the input end of the third drive amplifier module; one end of the secondary side of the transformer Xfrm3 is connected to the first input end of the drive amplifier DA3; the other end of the secondary side of the transformer Xfrm3 is connected to the second input end of the drive amplifier DA3; the first output end and the second output end of the drive amplifier DA3 are connected to a variable cross-coupled pair.

[0028] The first balanced-end amplifier module includes a balanced-end amplifier BA1, a transformer Xfmr4, and a transformer Xfmr7; the primary side of the transformer Xfmr4 is the input end of the first balanced amplifier module; the first end of the secondary side of the transformer Xfmr4 is connected to the first input end of the balanced-end amplifier BA1; the second end of the secondary side of the transformer Xfmr4 is connected to the second input end of the balanced-end amplifier BA1; the third end of the secondary side of the transformer Xfrm4 is connected to the output end of the adaptive bias circuit; the first output end of the balanced-end amplifier BA1 is connected to one end of the primary side of the transformer Xfmr7; the second output end of the balanced-end amplifier BA2 is connected to the other end of the primary side of the transformer Xfmr7; one end of the secondary side of the transformer Xfmr7 is connected to one end of the through end of the differential 90° coupler Q3; the other end of the secondary side of the transformer Xfmr7 is connected to the other end of the through end of the differential 90° coupler Q3.

[0029] The second balanced-end amplifier module includes a balanced-end amplifier BA2, a transformer Xfmr5, and a transformer Xfmr8; the primary side of the transformer Xfmr5 is the input end of the second balanced amplifier module; the first end of the secondary side of the transformer Xfmr5 is connected to the first input end of the balanced-end amplifier BA2; the second end of the secondary side of the transformer Xfmr5 is connected to the second input end of the balanced-end amplifier BA2; the third end of the secondary side of the transformer Xfrm5 is connected to the output end of the adaptive bias circuit; the first output end of the balanced-end amplifier BA2 is connected to one end of the primary side of the transformer Xfmr8; the second output end of the balanced-end amplifier BA2 is connected to the other end of the primary side of the transformer Xfmr8; one end of the secondary side of the transformer Xfmr8 is connected to one end of the coupled end of the differential 90° coupler Q3; the other end of the secondary side of the transformer Xfmr8 is connected to the other end of the coupled end of the differential 90° coupler Q3.

[0030] The variable cross-coupling pair includes transistors M1, M2, and M3; the base-collector of transistor M1 is connected to the second output terminal of drive amplifier DA3, the collector of transistor M2, and the control terminal amplifier module; the base-collector of transistor M2 is connected to the first output terminal of drive amplifier DA3, the collector of transistor M1, and the control terminal amplifier module; the emitter of transistor M1 is connected to the collector of transistor M3 and the emitter of transistor M2; the emitter of transistor M3 is grounded; the base-collector of transistor M3 is connected to the output terminal of the adaptive bias circuit.

[0031] The control terminal amplifier module includes control terminal amplifier CA, transformer Xfmr6, and transformer Xfmr9; the primary side of transformer Xfmr6 serves as the input terminal of the control terminal amplifier module; one end of the secondary side of transformer Xfmr6 is connected to the first input terminal of control terminal amplifier CA; the other end of the secondary side of transformer Xfmr6 is connected to the second input terminal of control terminal amplifier CA; the first output terminal of control terminal amplifier CA is connected to one end of the primary side of transformer Xfmr9; the second output terminal of control terminal amplifier CA is connected to the other end of the primary side of transformer Xfmr9; one end of the secondary side of transformer Xfmr9 is connected to one end of the isolation terminal of differential 90° coupler Q3 of 90° coupler Q3; the other end of the secondary side of transformer Xfmr9 is connected to the other end of the isolation terminal of 90° coupler Q1.

[0032] As Figure 2 shown, the adaptive bias circuit includes transistors M4, resistor R LP , capacitor C LP , transistor M 4n , transistor M 5n , transistor M 6n , transistor M 4p , transistor M 5p , transistor M 6p , resistor R1, resistor R2, capacitor C1, capacitor C2, capacitor C3, and capacitor C4;

[0033] One end of capacitor C1 serves as the input terminal of the adaptive bias circuit; the other end of capacitor C1 is connected to one end of resistor R1 and the base of transistor M4; the other end of resistor R1 is connected to the detection voltage; the emitter of transistor M4 is grounded; the collector of transistor M4 is connected to one end of resistor R LP , one end of capacitor C LP , the base of transistor M 4n , the base of transistor M 5n , the base of transistor M 6n , the base of transistor M 4p , the base of transistor M 5p , the base of transistor M 6pThe base of; resistor R LP The other end is connected to a 1V power supply and capacitor C LP The other end of; transistor M 4p The collector of is connected to the bias voltage V cnt1 ; transistor M 5p The collector of is connected to the bias voltage V cnt1 ; transistor M 6p The collector of is connected to the bias voltage V cnt2 ; transistor M 4p The emitter of is connected to one end of capacitor C4, one end of resistor R2, and transistor M 4n The other end of capacitor C4 is grounded; transistor M 4n The emitter of is grounded; transistor M 5p The emitter of is connected to one end of capacitor C3, one end of resistor R3, and transistor M 5n The other end of capacitor C3 is grounded; transistor M 5n The emitter of is grounded; transistor M 6p The emitter of is connected to one end of capacitor C2, one end of resistor R4, and transistor M 6n The other end of capacitor C2 is grounded; transistor M 6n The other end of resistor R2 is used as the first output terminal of the adaptive bias circuit; the other end of resistor R3 is used as the second output terminal of the adaptive bias circuit; the other end of resistor R4 is used as the third output terminal of the adaptive bias circuit.

[0034] As Figure 3 shown, the drive amplifier DA3 can be equivalent to the current source I in the figure out , whose parasitic capacitance is C out ; the control amplifier CA is equivalent to the input resistor R in and the input capacitance C in ; the variable cross-coupled pair is equivalent to a variable resistor, obtaining

[0035]

[0036] After inserting a variable cross-coupled pair between DA3 and Xfmr6, the load impedance of DA3 changes from Z L to Z Lv

[0037]

[0038] DA3 linearly amplifies its input voltage V in , whose transconductance is G m , obtaining:

[0039] V1 = I out ×Z Lv= G m V in Z Lv

[0040]

[0041] As Figure 4 shown, the variable cross-coupled pair structure improves the linearity of the control-end amplifier CA when it operates in the saturation region. BA1 / 2 uses an adaptive biasing technique to increase its gain in the saturation region. Due to the use of the variable cross-coupled pair structure, the voltage threshold of the adaptive biasing is set relatively high, avoiding the deterioration of the efficiency in the power back-off region caused by the premature turn-on of BA1 / 2. Figure 4 (b) shows that only the adaptive biasing technique is used to improve the overall linearity. Due to the large power back-off range, to compensate for the severely compressed gain of CA in saturation, the voltage threshold of the adaptive biasing needs to be set relatively low to increase the gain after BA is turned on, which will cause the premature turn-on of BA1 / 2 and lead to the deterioration of the power back-off efficiency.

[0042] As Figure 5 shown, the solid line is the simulation test result of the present invention using the variable cross-coupled pair structure, the dashed line is the simulation test result of the same circuit parameters without using the variable cross-coupled pair structure, and the dotted line is the simulation test result of only using the adaptive biasing technique to improve the linearity. The combination of the variable cross-coupled pair structure and the adaptive biasing technique (solid line) improves the overall linearity of the amplifier; turning off the cross-coupled pair structure and maintaining the same adaptive biasing voltage threshold (dashed line) deteriorates the linearity of the amplifier and slightly decreases the power back-off efficiency; turning off the cross-coupled pair and increasing the voltage threshold of the adaptive biasing (dotted line) improves the linearity of the amplifier but severely deteriorates the power back-off efficiency. The combination of the variable cross-coupled pair structure and the adaptive biasing technique avoids the deterioration of the power back-off efficiency caused by the premature turn-on of BA1 / 2 due to the high adaptive biasing voltage threshold.

[0043] In an embodiment of the present invention, the present invention achieves an 8.5 dB improvement in power back-off efficiency at 28 GHz; compared with only using the adaptive biasing technique, the variable cross-coupled pair structure improves the linearity of the millimeter-wave load modulation balanced amplifier and increases the back-off efficiency. A DC voltage that increases with the increase of the input signal power is output through the adaptive biasing ADB to control the gate of the transistor M3, so that g mc increases and thus Z Lv increases, while G m decreases with the increase of the input signal power. The changing trends of the two with the increase of the input signal power are opposite, making V1 remain relatively constant. Therefore, the trend of the gain G DA3 of DA3 being compressed with the increase of the input power is slowed down.

[0044] The structure of the variable cross-coupled pair proposed by the present invention makes the load impedance of the common-source amplifier increase with power, thus compensating for the trend of the gain of the common-source amplifier to decrease with power, thereby improving the linearity of the amplifier, and this technology will not deteriorate the efficiency in the power back-off region.

Claims

1. A millimeter-wave load-modulated balanced amplifier based on a variable cross-coupling pair, characterized in that: The system comprises an adaptive bias circuit, a first balanced-end amplifier module, a second balanced-end amplifier module, a control-end amplifier module, a first driver amplifier module, a second driver amplifier module, a third driver amplifier module, a variable cross-coupling pair, a resistor R5, a resistor R6, a differential 90° coupler Q1, a differential 90° coupler Q2, and a differential 90° coupler Q3; The input end of the adaptive bias circuit and the third input end of the differential 90° coupler Q1 serve as the input end of the amplifier. The output end of the adaptive bias circuit is respectively connected to the bias end of the first driver amplifier module, the bias end of the second driver amplifier module, the bias end of the first balanced-end amplifier module, the bias end of the second balanced-end amplifier module, and the variable cross-coupling pair. One end of the isolation end of the differential 90° coupler Q1 is connected to the other end of the isolation end of the differential 90° coupler Q1 through the resistor R5. One end of the through end of the differential 90° coupler Q1 is connected to the differential 90° coupler Q1. The first input terminal of the differential 90° coupler Q2 is connected; the other end of the through-terminal of the differential 90° coupler Q1 is connected to the second input terminal of the differential 90° coupler Q2; one end of the isolated terminal of the differential 90° coupler Q2 is connected to the other end of the isolated terminal of the differential 90° coupler Q2 through the resistance of the resistor R6; the third output terminal of the differential 90° coupler Q1 is connected to the input terminal of the third driver amplifier module; the output terminal of the third driver amplifier module is connected to the input terminal of the variable cross-coupling pair, and the output terminal of the variable cross-coupling pair is connected to the input terminal of the control-end amplifier module; the coupling terminal of the differential 90° coupler Q2 is connected to the input terminal of the control-end amplifier module. One end of the differential 90° coupler Q2 is connected to the first input end of the first driver amplifier module; the other end of the coupling end of the differential 90° coupler Q2 is connected to the second input end of the first driver amplifier module; one end of the straight-through end of the differential 90° coupler Q2 is connected to the first input end of the second driver amplifier module; the other end of the straight-through end of the differential 90° coupler Q2 is connected to the second input end of the second driver amplifier module; the output end of the first driver amplifier module is connected to the input end of the first balanced-end amplifier module; the output end of the second driver amplifier module is connected to the input end of the second balanced-end amplifier module; the first balanced-end amplifier The first output end and the second output end of the module are connected to one end of the straight-through end of the differential 90° coupler Q3 and the other end of the straight-through end of the differential 90° coupler Q3; the first output end of the second balanced-end amplifier module is connected to one end of the coupled end of the differential 90° coupler Q3; the second output end of the second balanced-end amplifier module is connected to the other end of the coupled end of the differential 90° coupler Q3; the output end of the control-end amplifier module is connected to the isolation end of the differential 90° coupler Q3; the output end of the differential 90° coupler Q3 serves as the output end of the millimeter-wave load-modulated balanced amplifier based on the variable cross-coupling pair.

2. The millimeter-wave load-modulated balanced amplifier based on a variable cross-coupling pair according to claim 1, characterized in that: The adaptive bias circuit includes a transistor M4, a resistor R LP , capacitor C LP , transistor M 4n , transistor M 5n , transistor M 6n , transistor M 4p , transistor M 5p , transistor M 6p , resistor R1, resistor R2, resistor R3, resistor R4, capacitor C1, capacitor C2, capacitor C3 and capacitor C4; One end of the capacitor C1 serves as the input end of the adaptive bias circuit; the other end of the capacitor C1 is connected to one end of the resistor R1 and the base of the transistor M4; the other end of the resistor R1 is connected to the detection voltage; The emitter of transistor M4 is grounded; the collector of transistor M4 is connected to resistor R LP One end of the capacitor C LP One end of transistor M 4n The base of transistor M 5n The base of transistor M 6n The base of transistor M 4p The base of transistor M 5p The base of transistor M 6p The base of the resistor R LP The other end is connected to a 1V power supply and capacitor C LP The other end of transistor M 4p The emitter is connected to the bias voltage V cnt1 ; Transistor M 5p The emitter is connected to the bias voltage V cnt1 ; Transistor M 6p The emitter is connected to the bias voltage V cnt2 ; Transistor M 4p The collector of the transistor M is connected to one end of the capacitor C4, one end of the resistor R2 and the 4n The collector of the capacitor C4 is grounded; the other end of the transistor M 4n The emitter of transistor M is grounded; 5p The collector of the transistor M is connected to one end of the capacitor C3, one end of the resistor R3 and the 5n The collector of the capacitor C3 is grounded; the other end of the transistor M 5n The emitter of transistor M is grounded; 6p The collector of the transistor M is connected to one end of the capacitor C2, one end of the resistor R4 and the 6n The collector of the capacitor C2 is grounded; the other end of the transistor M 6n The emitter of the resistor R2 is grounded; the other end of the resistor R2 serves as the first output end of the adaptive bias circuit; the other end of the resistor R3 serves as the second output end of the adaptive bias circuit; and the other end of the resistor R4 serves as the third output end of the adaptive bias circuit.

3. The millimeter-wave load-modulated balanced amplifier based on a variable cross-coupling pair according to claim 1, characterized in that: The first driver amplifier module includes a transformer Xfrm1 and a driver amplifier DA1; the primary side of the transformer Xfrm1 is the input end of the first driver amplifier module; the first end of the secondary side of the transformer Xfrm1 is connected to the first input end of the driver amplifier DA1; the second end of the secondary side of the transformer Xfrm1 is connected to the second input end of the driver amplifier DA1; the third end of the secondary side of the transformer Xfrm1 is connected to the output end of the adaptive bias circuit; the first output end and the second output end of the driver amplifier DA1 are connected to the first balanced end amplifier module.

4. The millimeter-wave load-modulated balanced amplifier based on a variable cross-coupling pair according to claim 3, characterized in that: The second driving amplifier module includes a transformer Xfrm2 and a driving amplifier DA2; the primary side of the transformer Xfrm2 is the input end of the second driving amplifier module; the first end of the secondary side of the transformer Xfrm2 is connected to the first input end of the driving amplifier DA2; the second end of the secondary side of the transformer Xfrm2 is connected to the second input end of the driving amplifier DA2; the third end of the secondary side of the transformer Xfrm2 is connected to the output end of the adaptive bias circuit; the first output end and the second output end of the driving amplifier DA2 are connected to the second balanced end amplifier module.

5. The millimeter-wave load-modulated balanced amplifier based on a variable cross-coupling pair according to claim 3, characterized in that: The third driver amplifier module includes a transformer Xfrm3 and a driver amplifier DA3; the primary side of the transformer Xfrm3 is the input end of the third driver amplifier module; one end of the secondary side of the transformer Xfrm3 is connected to the first input end of the driver amplifier DA3; the other end of the secondary side of the transformer Xfrm3 is connected to the second input end of the driver amplifier DA3; the first output end and the second output end of the driver amplifier DA3 are connected to a variable cross-coupling pair.

6. The millimeter-wave load-modulated balanced amplifier based on a variable cross-coupling pair according to claim 3, characterized in that: The first balanced-end amplifier module includes a balanced-end amplifier BA1, a transformer Xfmr4 and a transformer Xfmr7; the primary side of the transformer Xfmr4 is the input end of the first balanced amplifier module; the first end of the secondary side of the transformer Xfmr4 is connected to the first input end of the balanced-end amplifier BA1; the second end of the secondary side of the transformer Xfmr4 is connected to the second input end of the balanced-end amplifier BA1; the third end of the secondary side of the transformer Xfmr4 is connected to the output end of the adaptive bias circuit; the first output end of the balanced-end amplifier BA1 is connected to one end of the primary side of the transformer Xfmr7; the second output end of the balanced-end amplifier BA1 is connected to the other end of the primary side of the transformer Xfmr7; one end of the secondary side of the transformer Xfmr7 is connected to one end of the through-end of the differential 90° coupler Q3; and the other end of the secondary side of the transformer Xfmr7 is connected to the other end of the through-end of the differential 90° coupler Q3.

7. The millimeter-wave load-modulated balanced amplifier based on a variable cross-coupling pair according to claim 3, characterized in that: The second balanced-end amplifier module includes a balanced-end amplifier BA2, a transformer Xfmr5 and a transformer Xfmr8; the primary side of the transformer Xfmr5 is the input end of the second balanced amplifier module; the first end of the secondary side of the transformer Xfmr5 is connected to the first input end of the balanced-end amplifier BA2; the second end of the secondary side of the transformer Xfmr5 is connected to the second input end of the balanced-end amplifier BA2; the third end of the secondary side of the transformer Xfmr5 is connected to the output end of the adaptive bias circuit; the first output end of the balanced-end amplifier BA2 is connected to one end of the primary side of the transformer Xfmr8; the second output end of the balanced-end amplifier BA2 is connected to the other end of the primary side of the transformer Xfmr8; one end of the secondary side of the transformer Xfmr8 is connected to one end of the coupled end of the differential 90° coupler Q3; and the other end of the secondary side of the transformer Xfmr8 is connected to the other end of the coupled end of the differential 90° coupler Q3.

8. The millimeter-wave load-modulated balanced amplifier based on a variable cross-coupling pair according to claim 5, wherein the variable cross-coupling pair comprises a transistor M1, a transistor M2, and a transistor M3; The base set of the transistor M1 is connected to the second output terminal of the driver amplifier DA3, the collector of the transistor M2 and the control end amplifier module; The base set of the transistor M2 is connected to the first output terminal of the driver amplifier DA3, the collector of the transistor M1 and the control end amplifier module; The emitter of the transistor M1 is connected to the collector of the transistor M3 and the emitter of the transistor M2; the emitter of the transistor M3 is grounded; and the base-collector of the transistor M3 is connected to the output end of the adaptive bias circuit.

9. According to the millimeter-wave load-modulated balanced amplifier based on a variable cross-coupling pair described in claim 8, the control-end amplifier module includes a control-end amplifier CA, a transformer Xfmr6 and a transformer Xfmr9; the primary side of the transformer Xfmr6 serves as the input end of the control-end amplifier module; one end of the secondary side of the transformer Xfmr6 is connected to the first input end of the control-end amplifier CA; the other end of the secondary side of the transformer Xfmr6 is connected to the second input end of the control-end amplifier CA; the first output end of the control-end amplifier CA is connected to one end of the primary side of the transformer Xfmr9; the second output end of the control-end amplifier CA is connected to the other end of the primary side of the transformer Xfmr9; one end of the secondary side of the transformer Xfmr9 is connected to one end of the isolation end of the differential 90° coupler Q3; and the other end of the secondary side of the transformer Xfmr9 is connected to the other end of the isolation end of the differential 90° coupler Q3.

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