Four-frequency-band reconfigurable load modulation balanced amplifier structure and regulation and control method thereof

Abstract

The invention provides a four-frequency-band reconfigurable load modulation balanced amplifier structure and a regulation and control method thereof, and aims to solve the problems that in the existing power amplifier technology, the efficiency is low during power back-off, and multi-scene requirements cannot be met. The four-frequency-band reconfigurable load modulation balanced amplifier comprises a 90-degree Lange coupler of an input port and a 90-degree Lange coupler of an output port; a two-stage reconfigurable balanced power amplifier composed of an input matching network, a reconfigurable inter-stage matching network and an output-stage pre-matching network and a two-stage control signal power amplifier are combined through an active load modulation technology and a reconfigurable technology, a compact matching network is utilized, and a reconfigurable power amplifier is formed. The efficiency of output power rollback is greatly improved, and the system requirements in different frequency band application scenes can be met.

Description

Technical Field

[0001] The present invention relates to the field of radio frequency communication, and in particular to a four-band reconfigurable load modulation balanced amplifier structure and a control method thereof. Background Art

[0002] As wireless communication, intelligent sensing and other systems are widely used in people's daily life and military construction, the characteristics of modern communication technology, such as large capacity, multi-carrier, multi-level, wide bandwidth, high peak-to-average ratio, complex working environment, and tight spectrum resources, have put forward higher requirements on the efficiency of RF power amplifiers during power back-off and multi-operating frequency bands.

[0003] Currently, load modulation technology is mainly used to improve the efficiency during power back-off. Common load modulation circuit structures include Doherty architecture and Out-phasing architecture. However, there are still problems such as unsatisfactory modulation effect, high load sensitivity, and inability to apply multi-working frequency band functions. Summary of the invention

[0004] In order to overcome the deficiencies of the prior art, the present invention provides a four-band reconfigurable load-modulated balanced amplifier structure and a control method thereof. The four-band reconfigurable load-modulated balanced amplifier proposed in the present invention is composed of a 90° Lange coupler, a reconfigurable balanced power amplifier, and a control signal power amplifier. It combines a load-modulated balanced amplifier (LMBA) with reconfigurable technology, and controls the amplitude and phase of the signal to make the power amplifier have high linearity, maintain high efficiency performance when the output power is backed off, and can meet application requirements in different scenarios, realize multi-functions, and significantly improve its integration.

[0005] In order to achieve the above object, the present invention provides a four-band reconfigurable load-modulated balanced amplifier structure, which includes:

[0006] A 90° Lange coupler, a pair of reconfigurable balanced power amplifiers, and a control signal power amplifier are arranged at an input port and an output port; the input end and the output end of the pair of reconfigurable balanced power amplifiers are connected between the through end and the coupling end correspondingly connected to the 90° Lange coupler at the input port and the 90° Lange coupler at the output port; the isolation end of the 90° Lange coupler at the input port is connected to an ohmic resistor and then grounded, and the isolation end of the 90° Lange coupler at the output port is connected to the output end of the control signal power amplifier.

[0007] Preferably, the input end of the 90° Lange coupler of the input port receives a radio frequency signal, and the output end of the 90° Lange coupler of the output port outputs a radio frequency signal.

[0008] Preferably, each reconfigurable balanced power amplifier comprises: an input matching network, a reconfigurable inter-stage matching network, a pre-matching network, and bias networks corresponding to the input and output stages, which are connected in sequence.

[0009] Preferably, the reconfigurable inter-stage matching network includes a two-stage reconfigurable bridge switch capacitor structure and an inductor L4 connected between the two-stage reconfigurable bridge switch capacitor structure;

[0010] The equivalent circuit of the reconfigurable bridge switch capacitor structure of the front stage includes: a capacitor C6 and a switch S1 connected in sequence, a capacitor C8 and a switch S2 connected in sequence, the link where the capacitor C6 and the switch S1 are located is connected in parallel with the link where the capacitor C8 and the switch S2 are located; a capacitor C7 is also connected between the two links;

[0011] The equivalent circuit of the reconfigurable bridge switch capacitor structure at the later stage includes: capacitor C 10 and capacitor C 10 The switch S3 and the capacitor C9 are connected in parallel.

[0012] Preferably, the working state of the switch S1 is controlled by the control signal V1 received by its gate, the working state of the switch S2 is controlled by the control signal V2 received by its gate, and the working state of the switch S3 is controlled by the control signal V1 received by its gate.

[0013] Preferably, the input matching network uses broadband matching to achieve impedance matching at the input end.

[0014] Preferably, the control signal power amplifier comprises an input matching network, an inter-stage matching network, an output matching network, and bias networks corresponding to the input stage and the output stage, which are connected in sequence.

[0015] The present invention also provides a control method for controlling a quad-band reconfigurable load modulation balanced amplifier MMIC, wherein the specific control steps include:

[0016] Adjusting the working states of switches S1, S2, and S3 in an equivalent circuit corresponding to a reconfigurable balanced power amplifier or a reconfigurable main power amplifier;

[0017] The amplitude and phase of the control signal power amplifier are adjusted to control switches S1, S2 and S3 to operate in four different frequency bands.

[0018] Preferably, if the switch S1, the switch S2 and the switch S3 are all in short circuit, the corresponding control signal is input to adjust the amplitude and phase of the control signal power amplifier, and the quad-band reconfigurable load modulation balanced amplifier MMIC operates in the first frequency band;

[0019] If the switch S1 is in an open circuit, the switch S2 is in a short circuit, and the switch S3 is in an open circuit, a corresponding control signal is input to adjust the amplitude and phase of the control signal power amplifier, and the quad-band reconfigurable load-modulated balanced amplifier MMIC operates in the second frequency band;

[0020] If the switch S1 is in a short circuit, the switch S2 is in an open circuit, and the switch S3 is in a short circuit, a corresponding control signal is input to adjust the amplitude and phase of the control signal power amplifier, and the quad-band reconfigurable load modulation balanced amplifier MMIC operates in the third frequency band;

[0021] If the switch S1, the switch S2, and the switch S3 are all in an open circuit, and the corresponding control signal is input to adjust the amplitude and phase of the control signal power amplifier, the quad-band reconfigurable load modulation balanced amplifier MMIC operates in the fourth frequency band.

[0022] The invention provides a four-band reconfigurable load modulation balanced amplifier structure and a control method thereof, which has the following beneficial effects:

[0023] 1. Using the active load modulation technology LMBA architecture, by controlling the amplitude control and phase control of the signal power amplifier, the LMBA can achieve better impedance matching in both saturation and back-off states, thereby improving efficiency when the output power is backed off, with high linearity and high efficiency performance in multiple power modes.

[0024] 2. A reconfigurable matching network is added between the stages of the balanced power amplifier. The working states of switches S1, S2, and S3 are adjusted by two independent control signals V1 and V2, so that the function of working in four frequency bands can be realized. The single broadband is discretized into multiple narrowbands through the reconfigurable switch technology, and the gain of the LMBA and the efficiency of the pre-amplifier are improved by combining the two-stage power amplifier.

[0025] 3. A pre-matching structure is added to the output network of the balanced power amplifier to make it closer to the optimal load impedance point under higher power output conditions, and by setting the power ratio of load modulation in a reasonable range, the load modulation effect under high frequency and higher power output conditions is easier to achieve.

[0026] 4. By combining LMBA technology with reconfigurable technology, the 90° Lange coupler, two-stage reconfigurable balanced power amplifier, and two-stage control signal power amplifier are integrated into one, making it multifunctional.

[0027] 5. Use 90° Lange coupler for power distribution and synthesis. The reflected signal will be completely offset at the input and output ports, so that the input and output have good reflection coefficients in a wide frequency band and have good load insensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of the structure of a four-band reconfigurable load-modulated balanced amplifier provided by the present invention;

[0029] Figure 2 A reconfigurable inter-stage matching network and an equivalent schematic diagram in an embodiment of the present invention;

[0030] Figure 3 A schematic diagram of the structure of a Lange coupler in one embodiment of the present invention;

[0031] Figure 4 A schematic diagram of the structure of a quad-band reconfigurable load-modulated balanced amplifier constructed in one embodiment of the present invention;

[0032] Figure 5 A schematic diagram of the structure of a complete four-band reconfigurable load-modulated balanced amplifier formed by cascading various circuits in one embodiment of the present invention;

[0033] Figure 6 The simulation performance diagram of small signal gain, input reflection coefficient and output reflection coefficient of the quad-band reconfigurable load-modulated balanced amplifier in the embodiment provided by the present invention;

[0034] Figure 7 This is a simulation performance diagram of the relationship between power added efficiency and output power obtained at 8 GHz, 8.7 GHz, 9.8 GHz, and 10.8 GHz for a structure of an embodiment provided by the present invention. DETAILED DESCRIPTION

[0035] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0036] like Figure 1As shown, the present invention provides a four-band reconfigurable load modulated balanced amplifier structure, which includes: 90° Lange couplers arranged at the input port and the output port, a pair of reconfigurable balanced power amplifiers, and a control signal power amplifier; the input end and the output end of the pair of reconfigurable balanced power amplifiers are connected between the through end and the coupling end correspondingly connected to the 90° Lange coupler of the input port and the 90° Lange coupler of the output port; the isolation end of the 90° Lange coupler of the input port is connected to an ohmic resistor and then grounded, and the isolation end of the 90° Lange coupler of the output port is connected to the output end of the control signal power amplifier.

[0037] Specifically, the input port of the 90° Lange coupler of the input port is used as the RF input, the isolation port is connected to a 50-ohm resistor, and the through port and the coupling port are respectively connected to the two input ends of the reconfigurable balanced power amplifier; the output port of the 90° Lange coupler of the output port is used as the RF output, the isolation port is connected to the output end of the control signal power amplifier, and the through port and the coupling port are respectively connected to the two output ends of the reconfigurable balanced power amplifier.

[0038] The present invention utilizes the LMBA architecture and adds a pre-matching network structure to the output end of a balanced power amplifier or a main power amplifier, so that it is closer to the optimal load impedance point under a higher power output condition, so that the load modulation effect under a higher power output condition is easier to achieve. At the same time, a reconfigurable switch technology is added to the design of the inter-stage matching network of the balanced power amplifier or the main power amplifier, so that four different inter-stage impedances are formed, thereby dividing the working frequency band into four areas and improving the efficiency of the front-stage power amplifier and the overall gain; in addition, the input end uses broadband matching to complete the input matching, so that it can meet all working frequency bands, thereby maximizing the gain; a reconfigurable balanced power amplifier is constructed by a pre-matching network, a reconfigurable inter-stage matching network, and a broadband input matching network.

[0039] In the present invention, each reconfigurable balanced power amplifier comprises: an input matching network, a reconfigurable inter-stage matching network, a pre-matching network, and bias networks corresponding to the input and output stages, which are connected in sequence.

[0040] Among them, the input matching network includes a resistor R1, a microstrip line TL1, a capacitor C1, an inductor L1, a capacitor C2, an inductor L2, a capacitor C3, a resistor R2 and an inductor L3 connected in sequence; the input matching network adopts broadband matching to complete the impedance matching of the input end so that it can meet all working frequency bands, thereby maximizing the gain.

[0041] The reconfigurable inter-stage matching network includes two symmetrically arranged reconfigurable bridge switch capacitor structures and an inductor L4 connected between the two reconfigurable bridge switch capacitor structures. The reconfigurable bridge switch capacitor structure of the previous stage includes two signal links in parallel, one of which includes a capacitor C6 and a switch tube M2 connected in sequence, a resistor R3 is connected between one end of the capacitor C6 and the switch tube M2 and the ground, a resistor R4 is connected between the other end of the switch tube M2 and the ground, and the control stage of the switch tube M2 receives a control signal V1. Similarly, the structure of the other signal link is the same as the previous signal link, including a capacitor C8, a resistor R5, a switch tube M3 and a resistor R6, and the control stage of the switch tube M3 receives a control signal V2. A capacitor C7 is connected between the parallel points where the two signal links are connected. The reconfigurable bridge switch capacitor structure of the subsequent stage also includes two signal links in parallel, one of which is symmetrical with the signal link in the reconfigurable bridge switch capacitor structure of the previous stage, and includes: a resistor R7, a switch tube M4, a resistor R8 and a capacitor C9, and the other signal link includes a capacitor C 10 The switch tube M4 is controlled by receiving the control signal V2.

[0042] The circuit of the reconfigurable bridge switch capacitor structure of the front stage can be equivalent to: capacitor C6 and switch S1 connected in sequence, capacitor C8 and switch S2 connected in sequence, the link where capacitor C6 and switch S1 are located is connected in parallel with the link where capacitor C8 and switch S2 are located; capacitor C7 is also connected between the two links; the circuit of the reconfigurable bridge switch capacitor structure of the rear stage can be equivalent to: capacitor C 10 and capacitor C 10 The switch S3 and capacitor C9 are connected in parallel. Resistor R3, switch tube M2, and resistor R4 are equivalent to switch S1, resistor R5, switch tube M3, and resistor R6 are equivalent to switch S2, and resistor R7, switch tube M4, and resistor R8 are equivalent to switch S3. The working state of switch S1 is controlled by the control signal V1 received by its gate, the working state of switch S2 is controlled by the control signal V2 received by its gate, and the working state of switch S3 is controlled by the control signal V1 received by its gate. By adjusting the working states of switches S1, S2, and S3 by two independent control signals V1 and control signal V2, the function of working in four frequency bands can be realized. The single broadband is discretized into multiple narrowbands through reconfigurable switch technology, and the gain and efficiency of LMBA are improved in combination with a two-stage power amplifier.

[0043] In the present invention, the pre-matching network is arranged at the output stage, which includes a microstrip line capacitor C connected in sequence 13 , capacitor C 14 , microstrip line TL5, microstrip line capacitance C 13 With capacitor C 14One end of the connection is connected to the inductor L6 and then grounded. By adding a pre-matching structure to the output network of the balanced power amplifier, it is closer to the optimal load impedance point under high power output conditions, and by setting the power ratio of the load modulation in a reasonable range, the load modulation effect under high frequency and high power output conditions is easier to achieve.

[0044] In the present invention, in the bias network at the input stage, the driver tube is composed of a single transistor M1, and the bias network of its gate includes a resistor R2, an inductor L3, a capacitor C4, a gate voltage V g1 The drain bias network consists of microstrip line TL2, capacitor C5, gate voltage V d1 In the bias network of the output stage, the amplifier tube is composed of transistors M5 and M6 connected in parallel, and the bias network of the gates of the two includes resistor R9, inductor L5, capacitor C connected in sequence. 11 , Gate voltage V g2 The bias network of the drain of the two includes the microstrip line TL4, capacitor C 12 , gate voltage V d2 Connect in sequence.

[0045] In the present invention, the control signal power amplifier is composed of a two-stage circuit, including a signal input matching network, an inter-stage matching network, an output matching network, and bias networks corresponding to the input stage and the output stage, which are connected in sequence.

[0046] The signal input matching network includes resistors R 10 , microstrip line TL6, capacitor C 15 , microstrip line TL7 and capacitor C 16 The inter-stage matching network includes a microstrip line TL9, a capacitor C 19 , inductor L8 and capacitor C 20 The output matching network consists of capacitors C 23 、Inductance L 10 , capacitor C 24 and microstrip line TL 11 Located in the bias network of the input stage of the control signal power amplifier, the driver tube consists of a single transistor M7, and the gate bias network includes resistors R 11 , inductor L7, capacitor C 17 , gate voltage V g3 The drain bias network includes the microstrip line TL8, capacitor C 18 , gate voltage V d3 In the bias network of the output stage, the amplifier includes two parallel transistors M8 and M9, and the bias network of the gates of the two transistors includes resistors R 12 , inductor L9, capacitor C21 , gate voltage V g4 The bias network of the drain of the two includes a microstrip line TL connected in sequence 10 , capacitor C 22 , gate voltage V d4 .

[0047] The control signal power amplifier modulates the input signal and outputs the power signal to the isolation end of the output Lange coupler. At the same time, by adjusting the amplitude and phase of the input signal of the control signal power amplifier, the load modulation of the balanced power amplifier can be completed, so that it can still maintain high efficiency performance when the output power is backed off. In addition, the control signal power amplifier has broadband and high efficiency performance, which can meet the modulation of four working frequency bands. The control signal power amplifier can recover power at the output end through the Lange coupler, and improve the overall efficiency by improving the efficiency of the control signal power amplifier.

[0048] The present invention also provides a control method for controlling a quad-band reconfigurable load modulation balanced amplifier MMIC, wherein the specific control steps include:

[0049] Adjusting the working states of switches S1, S2, and S3 in an equivalent circuit corresponding to a reconfigurable balanced power amplifier or a reconfigurable main power amplifier;

[0050] The amplitude and phase of the control signal power amplifier are regulated, and switches S1, S2, and S3 are controlled to operate in four different frequency bands, so as to maintain high efficiency performance when the output power is backed off.

[0051] Specific control methods include:

[0052] If the switch S1, the switch S2 and the switch S3 are all in short circuit, the corresponding control signal is input to adjust the amplitude and phase of the control signal power amplifier, and the four-band reconfigurable load modulation balanced amplifier MMIC operates in the first frequency band;

[0053] If the switch S1 is in an open circuit, the switch S2 is in a short circuit, and the switch S3 is in an open circuit, a corresponding control signal is input to adjust the amplitude and phase of the control signal power amplifier, and the quad-band reconfigurable load-modulated balanced amplifier MMIC operates in the second frequency band;

[0054] If the switch S1 is in a short circuit, the switch S2 is in an open circuit, and the switch S3 is in a short circuit, a corresponding control signal is input to adjust the amplitude and phase of the control signal power amplifier, and the quad-band reconfigurable load modulation balanced amplifier MMIC operates in the third frequency band;

[0055] If the switch S1, the switch S2, and the switch S3 are all in an open circuit, and the corresponding control signal is input to adjust the amplitude and phase of the control signal power amplifier, the quad-band reconfigurable load modulation balanced amplifier MMIC operates in the fourth frequency band.

[0056] If the open circuit and short circuit states of the switches S1, S2 and S3 are controlled by switching the high and low levels of the control signals V1 and V2, the control method specifically includes:

[0057] If the control signal V1 is at a high level and the control signal V2 is at a high level, the quad-band reconfigurable load modulation balanced amplifier MMIC operates in the first frequency band;

[0058] If the control signal V1 is at a low level and the control signal V2 is at a high level, the quad-band reconfigurable load modulation balanced amplifier MMIC operates in the second frequency band;

[0059] If the control signal V1 is at a high level and the control signal V2 is at a low level, the quad-band reconfigurable load modulation balanced amplifier MMIC operates in the third frequency band;

[0060] If the control signal V1 is at a low level and the control signal V2 is at a low level, the quad-band reconfigurable load modulation balanced amplifier MMIC operates in the fourth frequency band.

[0061] Based on a four-band reconfigurable load modulation balanced amplifier structure, the present invention provides a four-band reconfigurable load modulation balanced amplifier structure design example, and the specific design steps include:

[0062] S1: Design of a reconfigurable balanced power amplifier.

[0063] The balanced power amplifier includes two completely symmetrical links. Due to the 90° Lange couplers at the input and output ends, the reflected signals of the two paths will be completely offset at the input and output ports, so that the input and output have good reflection coefficients in a wide frequency band and reduce load sensitivity. The design of a reconfigurable balanced power amplifier needs to comprehensively consider the performance of power, efficiency, gain, stability, reconfigurability, modulation effect, etc., select appropriate transistors, operating voltages and circuit topologies, including the size of transistors at each stage, the pre-matching network of the output stage, the reconfigurable inter-stage matching network, the input matching network and the design of bias networks at each stage.

[0064] S1.1: Design of transistor sizes at each level.

[0065] The design of transistor size needs to consider performance such as output power, drive power, and gain.

[0066] In this embodiment, the (output stage) rear-stage transistor uses two transistors with a total gate width of 400um in parallel to increase the output power and provide a certain amount of gain, and the (input stage) front-stage transistor uses a single transistor with a total gate width of 400um to provide sufficiently large driving power and provide sufficiently large gain.

[0067] S1.2: Design of pre-matching network for output stage.

[0068] The traditional LMBA has no matching at the output stage of the balanced power amplifier and is directly connected to the Lange coupler at the output end. When designing at high frequency and high power, a large control signal needs to be injected for load modulation, which affects the efficiency of the overall circuit. The pre-matching structure of the balanced power amplifier output stage makes it closer to the optimal load impedance point under higher power output conditions, making the load modulation effect under high frequency and higher power output conditions easier to achieve.

[0069] In this embodiment, the optimal impedance value at a higher power in the required operating frequency band is measured by load-pull output stage transistors, and the capacitor C is selected. 13 , inductor L6, capacitor C 14 The formed double L-type topology is matched in series with the microstrip line TL5 to about 30 ohms, which can be close to the optimal impedance at higher power at different operating frequencies.

[0070] S1.3: Design of reconfigurable inter-stage matching network.

[0071] The design of reconfigurable inter-stage matching network needs to consider matching difficulty, efficiency, gain, modulation effect and other performance. By using reconfigurable switching technology, a single broadband is discretized into multiple narrowbands, thereby dividing the operating frequency band into four areas, which can improve the gain and the efficiency of the previous stage.

[0072] In this embodiment, Figure 2 As shown, a reconfigurable inter-stage matching network and an equivalent schematic diagram are shown, wherein resistors R3, R4, R5, R6, R7, and R8 are used to provide 0 potential to the source and drain of the switch tube, resistor R3, switch tube M2, and resistor R4 can be equivalent to switch S1, resistor R5, switch tube M3, and resistor R6 can be equivalent to switch S2, and resistor R7, switch tube M4, and resistor R8 can be equivalent to switch S3.

[0073] The reconfigurable inter-stage matching network can provide four impedances to correspond to the frequencies of the power amplifier in four working states. The first frequency band is 7.8-8.2 GHz, the second frequency band is 8.5-8.9 GHz, the third frequency band is 9.6-10 GHz, and the fourth frequency band is 10.6-11 GHz, represented by f1, f2, f3, and f4 respectively.

[0074] When switch S1 is short-circuited, switch S2 is short-circuited, and switch S3 is short-circuited, the impedance Z1 can be expressed as:

[0075]

[0076] Where j is the imaginary unit, C 6～10 Capacitors C6 to C 10 L4 is the inductance value of inductor L4.

[0077] When switch S1 is open, switch S2 is short, and switch S3 is open, the impedance Z2 can be expressed as:

[0078]

[0079] When switch S1 is short-circuited, switch S2 is open-circuited, and switch S3 is short-circuited, the impedance Z3 can be expressed as:

[0080]

[0081] When switch S1 is open, switch S2 is open, and switch S3 is open, impedance Z4 can be expressed as:

[0082]

[0083] S1.4: Input matching network design.

[0084] The design of the input matching network needs to meet broadband matching and port matching to maximize gain.

[0085] In this embodiment, the input matching adopts multi-branch broadband matching, which is composed of resistor R1, microstrip line TL1, capacitor C1, inductor L1, capacitor C2, inductor L2, capacitor C3, resistor R2, and inductor L3 connected in sequence. Among them, resistor R1 can increase the real part of the input impedance, reduce the matching difficulty, and increase the circuit stability. The input matching composed of resistors, inductors, capacitors, and microstrip lines can achieve conjugate matching with the through end and the coupled end of the coupler, reducing the gain loss of the power amplifier.

[0086] S1.5: Design of bias networks corresponding to the input and output stages.

[0087] The design of the bias network corresponding to the input stage and output stage needs to consider the operating characteristics of the transistor and the circuit stability to ensure that the circuit can work normally.

[0088] In this embodiment, the front stage (input stage) driver tube is composed of a single transistor M1, and the gate bias network is composed of a resistor R2, an inductor L3, a capacitor C4, and a gate voltage V g1 The drain bias network consists of microstrip line TL2, capacitor C5, gate voltage Vd1 The post-stage (output stage) amplifier consists of two transistors M5 and M6 connected in parallel, and the gate bias network consists of resistor R9, inductor L5, capacitor C 11 , gate voltage V g2 The subsequent drain bias network consists of microstrip line TL4, capacitor C 12 , gate voltage V d2 The resistors in the bias network at each level are used to increase the low-frequency stability of the circuit. The inductor L3, microstrip line TL2, inductor L5, and TL4 can suppress the leakage of AC signals (the microstrip line is theoretically selected to have a quarter wavelength, which can achieve the effect of DC short circuit and fundamental wave open circuit). The parallel capacitors C4, C5, and C 11 , C 12 The interference signal of the voltage source can be filtered out, and both transistors are biased in deep class AB working state.

[0089] Step 2: Design of control signal power amplifier.

[0090] The control signal power amplifier needs to have high efficiency performance to improve the overall power amplifier efficiency, and consider the performance such as broadband, power, gain, stability, modulation effect, etc., select appropriate transistors, operating voltage and circuit topology, including the size of transistors at each stage, output matching network, inter-stage matching network, input matching network and the design of bias networks at each stage.

[0091] In this embodiment, the control signal power amplifier is designed as a 7.5-11.5GHz two-stage broadband high-efficiency power amplifier. The rear stage (output stage) transistor uses two transistors with a total gate width of 400um in parallel to increase the output power and provide a certain amount of gain. The front stage (input stage) transistor uses a single transistor with a total gate width of 400um to provide a sufficiently large driving power and provide a sufficiently large gain. The output matching network is connected to the isolation end of the Lange coupler of the rear stage, completing the matching of the optimal load impedance of the rear stage transistor with the port; the inter-stage matching network realizes the matching of the optimal load impedance of the front stage transistor with the optimal source impedance of the rear stage transistor, achieving maximum efficiency; the input matching network constructs a broadband matching network, realizes conjugate matching with the port, and reduces gain loss. The bias network of each level adds resistors to increase stability, inductors / microstrip lines to prevent signal leakage, and capacitors to filter out interference signals. Both transistors are biased in a deep AB working state. The control signal power amplifier plays the role of load modulation and active matching.

[0092] Step 3: Design of 90° Lange coupler.

[0093] like Figure 3As shown, it is a 90° Lange coupler structure, which consists of 4 ports, port 1 is the input port, port 2 is the through port, port 3 is the isolation port, and port 4 is the coupling port. The through port and the coupling port have a 90° phase difference.

[0094] In this embodiment, a microstrip line is used to design a lange coupler, and the working frequency band is controlled by adjusting the coupler length L, and the coupling strength and direct loss are controlled by adjusting the spacing S and the line width W (the line width of the rear-stage coupler needs to consider the power tolerance), so that the working frequency band includes 7.5-12GHz, and the coupling strength and direct loss are close to 3dB. The input port of the 90° lange coupler at the input port is used as the RF input, the isolation port is connected to a 50 ohm resistor, and the direct port and the coupling port are respectively connected to the two input ends of the balanced power amplifier, which can be used to divide the input power equally. The output port of the 90° lange coupler at the output port is used as the RF output, the isolation port is connected to the output end of the control signal power amplifier, and the direct port and the coupling port are respectively connected to the two output ends of the balanced power amplifier, which can be used for the synthesis of the output power of the balanced power amplifier and the control power amplifier output power.

[0095] Step 4: Connect the 90° Lange couplers at the input and output ports, the reconfigurable balanced power amplifier, and the control signal power amplifier to obtain a complete four-band reconfigurable load modulated balanced amplifier for debugging and optimization, such as Figure 4 As shown, it is a quad-band reconfigurable load-modulated balanced amplifier structure.

[0096] Among them, the 90° Lange coupler structure of the output port, port 2 and port 4 are input ports, port 3 is an isolation port, port 1 is an output port, and the Z matrix and voltage and current relationships corresponding to the four ports are:

[0097]

[0098] Port 4 and port 2 correspond to the equivalent current sources I4 and I2 of the reconfigurable balanced power amplifier, and the control power amplifier of the isolated port 3 is equivalent to the current source I3. 1～4 is the equivalent voltage corresponding to ports 1 to 4. b1 and Z b2 is the impedance of the input port, Z0 is the characteristic impedance of the coupler, and the output current amplitude of the reconfigurable balanced power amplifier is equal, and the phase difference is 90 degrees, that is, I4=-I b , I2=-jI b , j is the imaginary unit, I b Indicates the current amplitude of ports 2 and 4, and the current amplitude of port 3 is I c , the phase difference with the output current I2 is φ, I3=-jI c ejφ , combined with the Z matrix impedance of the output Lange coupler (5), the port impedance can be expressed as:

[0099]

[0100] According to the above formula, the load impedance of the load modulation balanced amplifier can be modulated by the amplitude ratio and phase difference of the output current of the control signal power amplifier and the main power amplifier, which can theoretically contain the entire Smith chart. Port 1 power P b1 , the power P of port 2 b2 and the power P injected into the isolation port of the Lange coupler cs It can be expressed as:

[0101]

[0102]

[0103] Theoretically, the power P injected into the isolation port of the Lange coupler is cs can be fully recovered at the Lange coupler output port, and the total output power P out It can be expressed as:

[0104] P out =P b1 +P b2 +P cs ......(9),

[0105] Define the power ratio factor β between the control signal power amplifier and the single-branch balanced power amplifier:

[0106]

[0107] Reflection coefficient ρ viewed from port 2 or port 4:

[0108]

[0109] From (10) and (11), we can get:

[0110]

[0111] The power ratio factor β of the control signal and the main signal can be mapped on a set of reflection coefficient circles to represent the position of load impedance modulation. When the power ratio factor β is constant, the corresponding reflection coefficient is The center of the circle is the origin of the Simth circle. When the power phase difference θ between the control signal power amplifier signal and the balanced power amplifier signal increases, the reflection coefficient rotates counterclockwise on the circle. Amplitude modulation and phase modulation can be achieved based on the power ratio factor β and the phase difference θ.

[0112] In this embodiment, each circuit is cascaded to obtain a complete four-band reconfigurable load-modulated balanced amplifier, such as Figure 5 As shown, the overall circuit performance is simulated and the pre-matching network, reconfigurable inter-stage matching network, input matching network, and bias networks at each stage of the reconfigurable balanced power amplifier, as well as the output matching network, inter-stage matching network, input matching network, and bias networks at each stage of the auxiliary power amplifier are optimized respectively, and the optimization is iterated in a continuous cycle to obtain the optimal value of each device.

[0113] In view of the above-mentioned embodiment, the present invention also provides a control method for a four-band reconfigurable load-modulated balanced amplifier. The steps include: controlling the open circuit and short circuit states of switches S1 and S3 by control signal V1, controlling the open circuit and short circuit states of switch S2 by switching the high and low levels of control signal V2, adjusting the working states of switches S1, S2, and S3, and maintaining high efficiency performance when output power is backed off by amplitude control and phase control of the control signal power amplifier.

[0114] like Figure 6 As shown, the small signal gain, input reflection coefficient, and output reflection coefficient simulation performance of the quad-band reconfigurable load-modulated balanced amplifier.

[0115] Combined with the simulated amplitude control, phase control, and switch control strategies, the input signal RF in Sweep from -2dBm to 13dBm, 1dBm interval, control signal CS in Scan from -5dBm to 13dBm, with an interval of 1dBm, and scan the phase from 0 degree to 360 degrees, with an interval of 10 degrees. Adjust the control signal V1 and the control signal V2 to work in different frequency bands.

[0116] like Figure 7 As shown in the figure, the simulation performance of the relationship between power added efficiency and output power obtained at 8 GHz, 8.7 GHz, 9.8 GHz and 10.8 GHz respectively. The maximum point of power added efficiency corresponding to each output power is the optimal modulation effect at the output power. Compared with the efficiency of the normalized ideal class B power amplifier when the output power is backed off by 6 dB, the efficiency is improved by 6% at 8 GHz, 10% at 8.7 GHz, 15% at 9.8 GHz and 13% at 10.8 GHz.

[0117] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

Claims

1. A quad-band reconfigurable load-modulated balanced amplifier structure, characterized in that: include: 90° Lange couplers, a pair of reconfigurable balanced power amplifiers, and a control signal power amplifier are provided at the input port and the output port; A pair of reconfigurable balanced power amplifier input and output ends are connected between the through end and the coupling end correspondingly connected to the 90° Lange coupler of the input port and the 90° Lange coupler of the output port; the isolation end of the 90° Lange coupler of the input port is connected to an ohmic resistor and then grounded, and the isolation end of the 90° Lange coupler of the output port is connected to the output end of the control signal power amplifier.

2. The quad-band reconfigurable load-modulated balanced amplifier structure according to claim 1, characterized in that: The input end of the 90° Lange coupler of the input port receives a radio frequency signal, and the output end of the 90° Lange coupler of the output port outputs a radio frequency signal.

3. The quad-band reconfigurable load-modulated balanced amplifier structure according to claim 1, characterized in that: Each reconfigurable balanced power amplifier comprises: an input matching network, a reconfigurable inter-stage matching network, a pre-matching network, and bias networks corresponding to the input and output stages, which are connected in sequence.

4. The quad-band reconfigurable load-modulated balanced amplifier structure according to claim 3, characterized in that: The reconfigurable inter-stage matching network includes a two-stage reconfigurable bridge switch capacitor structure and an inductor L4 connected between the two-stage reconfigurable bridge switch capacitor structure; The equivalent circuit of the reconfigurable bridge switch capacitor structure of the front stage includes: a capacitor C6 and a switch S1 connected in sequence, a capacitor C8 and a switch S2 connected in sequence, the link where the capacitor C6 and the switch S1 are located is connected in parallel with the link where the capacitor C8 and the switch S2 are located; a capacitor C7 is also connected between the two links; The equivalent circuit of the reconfigurable bridge switch capacitor structure at the later stage includes: capacitor C 10 and capacitor C 10 The switch S3 and the capacitor C9 are connected in parallel.

5. The quad-band reconfigurable load-modulated balanced amplifier structure according to claim 4, characterized in that: The working state of the switch S1 is controlled by the control signal V1 received at its gate, the working state of the switch S2 is controlled by the control signal V2 received at its gate, and the working state of the switch S3 is controlled by the control signal V1 received at its gate.

6. The quad-band reconfigurable load-modulated balanced amplifier structure according to claim 3, characterized in that: The input matching network uses broadband matching to achieve impedance matching at the input end.

7. The quad-band reconfigurable load-modulated balanced amplifier structure according to claim 1, characterized in that: The control signal power amplifier comprises an input matching network, an inter-stage matching network, an output matching network, and bias networks corresponding to the input stage and the output stage, which are connected in sequence.

8. A control method for controlling the quad-band reconfigurable load modulated balanced amplifier MMIC according to any one of claims 1 to 7, characterized in that: The specific control steps include: Adjusting the working states of switches S1, S2, and S3 in an equivalent circuit corresponding to a reconfigurable balanced power amplifier or a reconfigurable main power amplifier; The amplitude and phase of the control signal power amplifier are adjusted to control switches S1, S2 and S3 to operate in four different frequency bands.

9. The control method according to claim 8, characterized in that: If the switch S1, the switch S2 and the switch S3 are all in short circuit, the corresponding control signal is input to adjust the amplitude and phase of the control signal power amplifier, and the four-band reconfigurable load modulation balanced amplifier MMIC operates in the first frequency band; If the switch S1 is in an open circuit, the switch S2 is in a short circuit, and the switch S3 is in an open circuit, a corresponding control signal is input to adjust the amplitude and phase of the control signal power amplifier, and the quad-band reconfigurable load-modulated balanced amplifier MMIC operates in the second frequency band; If the switch S1 is in a short circuit, the switch S2 is in an open circuit, and the switch S3 is in a short circuit, a corresponding control signal is input to adjust the amplitude and phase of the control signal power amplifier, and the quad-band reconfigurable load modulation balanced amplifier MMIC operates in the third frequency band; If the switch S1, the switch S2, and the switch S3 are all in an open circuit, and the corresponding control signal is input to adjust the amplitude and phase of the control signal power amplifier, the quad-band reconfigurable load modulation balanced amplifier MMIC operates in the fourth frequency band.

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