A cascaded dual-control class D power amplifier based on adaptive frequency conversion

Abstract

The present invention discloses a cascade dual-control Class D power amplifier based on adaptive frequency conversion, belonging to the technical field of amplifiers. The amplifier includes an error integration unit, a signal modulation unit and a signal demodulation unit, and also includes an adaptive frequency conversion control unit and a logic processing unit. The present invention overcomes the problem of excessively high fixed frequency and low efficiency of traditional power amplifiers under realistic working conditions with given low distortion through a frequency control loop formed by an adaptive frequency conversion control unit, and also solves the problem of insufficient bandwidth of traditional single-stage control when amplifying high-order harmonics and irregular complex waveforms by designing a cascade dual closed-loop control, successfully achieving low distortion, high bandwidth and strong load-carrying capacity of the power amplifier when processing high-order harmonics and irregular complex waveforms.

Description

Technical Field

[0001] The invention belongs to the technical field of amplifiers, and in particular relates to a class D power amplifier. Background Art

[0002] A power amplifier is an electronic device whose main function is to boost the power of an input signal to the required output power level. Depending on the voltage and current of the transistor in the amplified state (i.e. the position of the transistor's static operating point), power amplifiers can be divided into different types such as Class A, Class B, Class AB, Class C and Class D.

[0003] With the continuous advancement of industrial technology and the diversification of actual needs, the need to transform and improve traditional high-frequency modulation and control technology is becoming increasingly urgent. At present, the high-frequency modulation method commonly used in Class D power amplifiers is a fixed frequency method. Under the condition of ensuring low distortion, the problem of too high fixed frequency often occurs, resulting in reduced efficiency. In addition, most of the existing control methods are single-stage control. When amplifying signals containing high-order harmonics and irregular complex waveforms, it will lead to insufficient bandwidth and cannot meet the needs, thus affecting the quality and accuracy of the signal. Summary of the invention

[0004] The present invention proposes a cascade dual-control class D power amplifier based on adaptive frequency conversion, the purpose of which is: 1. to solve the problem of reduced efficiency caused by the fixed frequency mode; 2. to solve the problem of insufficient bandwidth existing in single-stage control.

[0005] The technical solution of the present invention is as follows:

[0006] A cascaded dual-control class D power amplifier based on adaptive frequency conversion, comprising an error integration unit, a signal modulation unit and a signal demodulation unit, and also comprising an adaptive frequency conversion control unit and a logic processing unit;

[0007] The first input terminal of the error integration unit is connected to the input terminal of the power amplifier, and the second input terminal is connected to the output terminal of the power amplifier; the error integration unit is used to eliminate the voltage deviation between the output signal and the input signal of the power amplifier;

[0008] The first input terminal of the adaptive frequency conversion control unit is connected to the output terminal of the error integration unit, and the second input terminal is connected to the output terminal of the logic processing unit; the adaptive frequency conversion control unit is used for frequency modulation of the amplitude signal output of the power amplifier;

[0009] The first input end of the signal modulation unit is connected to the output end of the adaptive frequency conversion control unit, and the second input end is connected to the output end of the power amplifier; the signal modulation unit is used to modulate the output signal of the adaptive frequency conversion control unit into a high-frequency carrier signal;

[0010] The input end of the logic processing unit is connected to the output end of the signal modulation unit to realize high-frequency carrier signal latching and level conversion;

[0011] The input end of the signal demodulation unit is connected to the output end of the logic processing unit, and is used to filter out the high-frequency component in the high-frequency carrier signal and output the signal to the output end of the power amplifier.

[0012] As a further improvement of the cascade dual-control Class D power amplifier based on adaptive frequency conversion: the error integration unit includes an operational amplifier D2B, a capacitor C1 and a resistor R5, the first input terminal of the error integration unit is connected to the inverting input terminal of the operational amplifier D2B through the resistor R5, and the inverting input terminal of the operational amplifier D2B is also connected to the output terminal of the operational amplifier D2B through the capacitor C1; the non-inverting input terminal of the operational amplifier D2B is the second input terminal of the error integration unit, and the output terminal of the operational amplifier D2B is the output terminal of the error integration unit.

[0013] As a further improvement of the cascade dual-control class D power amplifier based on adaptive frequency conversion: the adaptive frequency conversion control unit includes an adaptive frequency conversion control circuit, a subtraction circuit and an addition circuit.

[0014] As a further improvement of the cascade dual-control class D power amplifier based on adaptive frequency conversion: the input end of the adaptive frequency conversion control circuit is the second input end of the adaptive frequency conversion control unit, and the output end of the adaptive frequency conversion control circuit is connected to the second input end of the subtraction circuit and also connected to the second input end of the addition circuit;

[0015] The first input terminal of the subtraction circuit and the first input terminal of the addition circuit are both connected to the first input terminal of the adaptive frequency conversion control unit;

[0016] The output end of the subtraction circuit and the output end of the addition circuit are respectively the first output end and the second output end of the adaptive frequency conversion control unit.

[0017] As a further improvement of the cascade dual-control class D power amplifier based on adaptive frequency conversion: the adaptive frequency conversion control circuit includes a resistor R7, a resistor R10, a capacitor C2, a resistor C4 and an operational amplifier D5B;

[0018] The input end of the adaptive frequency conversion control circuit is connected to the non-inverting input end of the operational amplifier D5B through the resistor R7, and the non-inverting input end of the operational amplifier D5B is also grounded through the capacitor C2; the inverting input end of the operational amplifier D5B is connected to the output end of the operational amplifier D5B through the resistor R10, and the capacitor C4 is connected in parallel with the resistor R10; the output end of the operational amplifier D5B is the output end of the adaptive frequency conversion control circuit.

[0019] As a further improvement of the cascade dual-control class D power amplifier based on adaptive frequency conversion: the subtraction circuit includes a resistor R1, a resistor R2, a resistor R3, a resistor R6 and an operational amplifier D1B;

[0020] The first input terminal of the subtraction circuit is connected to the non-inverting input terminal of the operational amplifier D1B through the resistor R2, and the non-inverting input terminal of the operational amplifier D1B is also grounded through the resistor R1; the second input terminal of the subtraction circuit is connected to the inverting input terminal of the operational amplifier D1B through the resistor R3, and the inverting input terminal of the operational amplifier D1B is also connected to the output terminal of the operational amplifier D1B through the resistor R6; the output terminal of the operational amplifier D1B is the output terminal of the subtraction circuit.

[0021] As a further improvement of the cascade dual-control class D power amplifier based on adaptive frequency conversion: the adding circuit includes a resistor R8, a resistor R11, a resistor R12, a resistor R13 and an operational amplifier D6B;

[0022] The first input terminal of the adding circuit is connected to the non-inverting input terminal of the operational amplifier D6B through a resistor R8, the second input terminal of the adding circuit is connected to the non-inverting input terminal of the operational amplifier D6B through a resistor R11, the inverting input terminal of the operational amplifier D6B is grounded through a resistor R12, and is also connected to the output terminal of the operational amplifier D6B through a resistor R13; the output terminal of the operational amplifier D6B is the output terminal of the adding circuit.

[0023] As a further improvement of the cascade dual-control class D power amplifier based on adaptive frequency conversion: the first input end of the signal modulation unit includes a first sub-input end and a second sub-input end connected to the first output end and the second output end of the adaptive frequency conversion control unit respectively;

[0024] The signal modulation unit includes a voltage comparator D3 and a voltage comparator D4; the non-inverting input terminal of the voltage comparator D3 and the inverting input terminal of the voltage comparator D4 are respectively the first sub-input terminal and the second sub-input terminal of the signal modulation unit;

[0025] The inverting input terminal of the voltage comparator D3 and the non-inverting input terminal of the voltage comparator D4 are simultaneously connected to the second input terminal of the signal modulation unit;

[0026] The output terminal of the voltage comparator D3 and the output terminal of the voltage comparator D4 are respectively the first output terminal and the second output terminal of the signal modulation unit.

[0027] As a further improvement of the cascade dual-control class D power amplifier based on adaptive frequency conversion: the logic processing unit includes a NOR gate circuit D7B and a NOR gate circuit D4B, and also includes a resistor R4 and a resistor R9;

[0028] The first input end of the NOR gate circuit D7B is connected to the second output end of the signal modulation unit, and is also connected to the positive pole of the power supply through the resistor R4; the output end of the NOR gate circuit D7B is connected to the second input end of the NOR gate circuit D4B; the first input end of the NOR gate circuit D4B is connected to the first output end of the signal modulation unit, and is also connected to the positive pole of the power supply through the resistor R9; the output end of the NOR gate circuit D4B is connected to the second input end of the NOR gate circuit D7B; the output end of the NOR gate circuit D4B is the output end of the logic processing unit.

[0029] As a further improvement of the cascade dual-control class D power amplifier based on adaptive frequency conversion: the signal demodulation unit includes a field effect transistor V1, a field effect transistor V2, an inductor L1 and a capacitor C3;

[0030] The gate of the field effect tube V1 and the gate of the field effect tube V2 are both connected to the input end of the signal demodulation unit; the drain of the field effect tube V1 is connected to the positive power supply VS+, the source is connected to the drain of the field effect tube V2, and the source of the field effect tube V2 is connected to the negative power supply VS-;

[0031] The source of the field effect transistor V1 is also connected to the output end of the signal demodulation unit through the inductor L1 , and the output end of the signal demodulation unit is also grounded through the capacitor C3 .

[0032] Compared with the prior art, the present invention has the following positive effects:

[0033] 1. The frequency control loop formed by the adaptive frequency conversion control unit of the present invention overcomes the problem of too high fixed frequency and low efficiency of the traditional power amplifier under the actual working conditions of given low distortion. The cascade double closed-loop control is designed to solve the problem that the bandwidth of the traditional single-stage control cannot be satisfied when amplifying high-order harmonics and irregular complex waveforms, thereby achieving the purpose of low distortion, high bandwidth and large load capacity of the power amplifier when processing high-order harmonics and irregular complex waveforms.

[0034] 2. The adaptive frequency conversion control unit controls the upper limit of the power amplifier output frequency through a subtraction circuit, controls the lower limit of the power amplifier output frequency through an addition circuit, and performs frequency modulation according to the amplitude signal output of the power amplifier through an adaptive frequency conversion control circuit, thereby forming a frequency control loop to achieve adaptive tracking of the modulation frequency and ensure efficient and stable output of the power amplifier.

[0035] 3. The present invention forms a cascade double closed-loop control through a primary control loop and a secondary control loop, thereby eliminating the voltage deviation between the output signal and the input signal of the power amplifier, improving the dynamic response speed of the system, and ensuring low distortion rate and low distortion of the output signal of the power amplifier. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is the overall architecture diagram of the present invention;

[0037] Figure 2 It is a circuit diagram of the present invention. DETAILED DESCRIPTION

[0038] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0039] like Figure 1 A cascade dual-control class D power amplifier based on adaptive frequency conversion includes an error integration unit, an adaptive frequency conversion control unit, a signal modulation unit, a logic processing unit and a signal demodulation unit.

[0040] (1) Error integration unit:

[0041] The first input end of the error integration unit is connected to the input end of the power amplifier, and the second input end is connected to the output end of the power amplifier to form a primary control loop. The error integration unit is used to eliminate the voltage deviation between the output signal and the input signal of the power amplifier.

[0042] Specifically, Figure 2 , the error integration unit includes an operational amplifier D2B, a capacitor C1 and a resistor R5. The first input terminal of the error integration unit is connected to the inverting input terminal of the operational amplifier D2B through the resistor R5, and the inverting input terminal of the operational amplifier D2B is also connected to the output terminal of the operational amplifier D2B through the capacitor C1. The non-inverting input terminal of the operational amplifier D2B is the second input terminal of the error integration unit, and the output terminal of the operational amplifier D2B is the output terminal of the error integration unit. The capacitor C1, the resistor R5 and the operational amplifier D2B form a first-order integration circuit, and form a primary control loop with the output terminal of the power amplifier, which can eliminate the voltage deviation between the output sampling signal of the power amplifier and the input signal of the power amplifier, improve the dynamic response speed of the system, and achieve high-bandwidth output.

[0043] (2) Adaptive frequency conversion control unit:

[0044] like Figure 1 The first input terminal of the adaptive frequency conversion control unit is connected to the output terminal of the error integration unit, and the second input terminal is connected to the output terminal of the logic processing unit to form a frequency control loop. The adaptive frequency conversion control unit is used for frequency modulation of the amplitude signal output of the power amplifier.

[0045] Specifically, Figure 2, the adaptive frequency conversion control unit includes an adaptive frequency conversion control circuit, a subtraction circuit and an addition circuit. The input end of the adaptive frequency conversion control circuit is the second input end of the adaptive frequency conversion control unit, and the output end of the adaptive frequency conversion control circuit is connected to the second input end of the subtraction circuit and the second input end of the addition circuit. The first input end of the subtraction circuit and the first input end of the addition circuit are both connected to the first input end of the adaptive frequency conversion control unit. The output end of the subtraction circuit and the output end of the addition circuit are respectively the first output end and the second output end of the adaptive frequency conversion control unit.

[0046] (2.1) Adaptive frequency conversion control circuit:

[0047] The adaptive frequency conversion control circuit includes a resistor R7, a resistor R10, a capacitor C2, a resistor C4 and an operational amplifier D5B. The input end of the adaptive frequency conversion control circuit is connected to the non-inverting input end of the operational amplifier D5B through the resistor R7, and the non-inverting input end of the operational amplifier D5B is also grounded through the capacitor C2. The inverting input end of the operational amplifier D5B is connected to the output end of the operational amplifier D5B through the resistor R10, and the capacitor C4 is connected in parallel with the resistor R10. The output end of the operational amplifier D5B is the output end of the adaptive frequency conversion control circuit.

[0048] The adaptive frequency conversion control circuit can increase the modulation frequency when the power amplifier outputs a low-amplitude signal, and reduce the modulation frequency when it outputs a high-amplitude signal. At the same time, it forms a frequency control loop with the output of the logic processing unit to achieve adaptive tracking of the modulation frequency, thereby ensuring high efficiency and high-load output under low-distortion conditions.

[0049] (2.2) Subtraction circuit:

[0050] The subtraction circuit includes a resistor R1, a resistor R2, a resistor R3, a resistor R6 and an operational amplifier D1B. The first input terminal of the subtraction circuit is connected to the non-inverting input terminal of the operational amplifier D1B through the resistor R2, and the non-inverting input terminal of the operational amplifier D1B is also grounded through the resistor R1. The second input terminal of the subtraction circuit is connected to the inverting input terminal of the operational amplifier D1B through the resistor R3, and the inverting input terminal of the operational amplifier D1B is also connected to the output terminal of the operational amplifier D1B through the resistor R6. The output terminal of the operational amplifier D1B is the output terminal of the subtraction circuit.

[0051] The subtraction circuit is used to control the upper limit value of the output frequency of the power amplifier.

[0052] (2.3) Adding circuit:

[0053] The adding circuit includes a resistor R8, a resistor R11, a resistor R12, a resistor R13 and an operational amplifier D6B. The first input terminal of the adding circuit is connected to the non-inverting input terminal of the operational amplifier D6B through the resistor R8, the second input terminal of the adding circuit is connected to the non-inverting input terminal of the operational amplifier D6B through the resistor R11, the inverting input terminal of the operational amplifier D6B is grounded through the resistor R12, and is also connected to the output terminal of the operational amplifier D6B through the resistor R13. The output terminal of the operational amplifier D6B is the output terminal of the adding circuit.

[0054] The adding circuit is used to control the lower limit value of the output frequency of the power amplifier.

[0055] (3) Signal modulation unit:

[0056] like Figure 1 The first input end of the signal modulation unit is connected to the output end of the adaptive frequency conversion control unit, and the second input end is connected to the output end of the power amplifier to form a secondary control loop. The signal modulation unit is used to modulate the output signal of the adaptive frequency conversion control unit into a high-frequency carrier signal.

[0057] like Figure 2 The first input end of the signal modulation unit includes a first sub-input end and a second sub-input end which are respectively connected to the first output end and the second output end of the adaptive frequency conversion control unit.

[0058] The signal modulation unit includes an ultra-high-speed voltage comparator D3 and an ultra-high-speed voltage comparator D4. The non-inverting input terminal of the voltage comparator D3 and the inverting input terminal of the voltage comparator D4 are respectively the first sub-input terminal and the second sub-input terminal of the signal modulation unit.

[0059] The inverting input terminal of the voltage comparator D3 and the non-inverting input terminal of the voltage comparator D4 are simultaneously connected to the second input terminal of the signal modulation unit, which are used to receive the output signal of the power amplifier, form a secondary control loop, and modulate the output signal of the adaptive frequency conversion control unit into a high-frequency carrier signal, thereby ensuring low distortion rate and low distortion of the output signal of the power amplifier.

[0060] The output terminal of the voltage comparator D3 and the output terminal of the voltage comparator D4 are respectively the first output terminal and the second output terminal of the signal modulation unit.

[0061] (4) Logical processing unit:

[0062] like Figure 1 The input end of the logic processing unit is connected to the output end of the signal modulation unit to realize high-frequency carrier signal latching and level conversion.

[0063] Specifically, Figure 2, the logic processing unit includes a NOR gate circuit D7B and a NOR gate circuit D4B, and also includes a resistor R4 and a resistor R9. The first input end of the NOR gate circuit D7B is connected to the second output end of the signal modulation unit, and is also connected to the positive pole of the power supply through the resistor R4. The output end of the NOR gate circuit D7B is connected to the second input end of the NOR gate circuit D4B. The first input end of the NOR gate circuit D4B is connected to the first output end of the signal modulation unit, and is also connected to the positive pole of the power supply through the resistor R9. The output end of the NOR gate circuit D4B is connected to the second input end of the NOR gate circuit D7B. The output end of the NOR gate circuit D4B is the output end of the logic processing unit.

[0064] Integrated circuits D7B, D4B and resistors R4, R9 form a high-speed RS trigger circuit for latching and level conversion of high-frequency carrier signals.

[0065] (5) Signal demodulation unit:

[0066] like Figure 1 The input end of the signal demodulation unit is connected to the output end of the logic processing unit, which is used to filter out the high-frequency components in the high-frequency carrier signal, reduce the change rate of the carrier signal, and output the signal to the output end of the power amplifier.

[0067] Specifically, Figure 2 , the signal demodulation unit includes a field effect tube V1, a field effect tube V2, an inductor L1 and a capacitor C3. The gate of the field effect tube V1 and the gate of the field effect tube V2 are both connected to the input end of the signal demodulation unit. The drain of the field effect tube V1 is connected to the positive power supply VS+, the source is connected to the drain of the field effect tube V2, and the source of the field effect tube V2 is connected to the negative power supply VS-. The source of the field effect tube V1 is also connected to the output end of the signal demodulation unit through the inductor L1, and the output end of the signal demodulation unit is also grounded through the capacitor C3.

[0068] When working, the error integration unit eliminates the voltage deviation between the input signal of the power amplifier and the output signal of the power amplifier and outputs it to the adaptive frequency conversion control unit. The adaptive frequency conversion control unit performs frequency modulation according to the amplitude signal output of the power amplifier and outputs it to the signal modulation unit. The signal modulation unit modulates the output signal of the adaptive frequency conversion control unit into a high-frequency carrier signal and outputs it to the logic processing unit. The logic processing unit performs high-frequency carrier signal latching and level conversion and then outputs it to the signal demodulation unit. The signal demodulation unit filters out the high-frequency components in the carrier signal to output the power amplifier. The frequency control loop can realize adaptive tracking of the modulation frequency, ensuring the high efficiency and high load output of the power amplifier under low distortion conditions; the primary control loop and the secondary control loop constitute a cascade double closed-loop controller, which can improve the dynamic response speed of the system and ensure the low distortion rate and low distortion of the output signal of the power amplifier.

[0069] It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. The scope of the present invention is defined by the claims rather than the above description.

Claims

1. A cascaded dual-control class D power amplifier based on adaptive frequency conversion, comprising an error integration unit, a signal modulation unit and a signal demodulation unit, characterized in that: It also includes an adaptive frequency conversion control unit and a logic processing unit; The first input terminal of the error integration unit is connected to the input terminal of the power amplifier, and the second input terminal is connected to the output terminal of the power amplifier; the error integration unit is used to eliminate the voltage deviation between the output signal and the input signal of the power amplifier; The first input terminal of the adaptive frequency conversion control unit is connected to the output terminal of the error integration unit, and the second input terminal is connected to the output terminal of the logic processing unit; the adaptive frequency conversion control unit is used for frequency modulation of the amplitude signal output of the power amplifier; The adaptive frequency conversion control unit comprises an adaptive frequency conversion control circuit, a subtraction circuit and an addition circuit; The input end of the adaptive frequency conversion control circuit is the second input end of the adaptive frequency conversion control unit, and the output end of the adaptive frequency conversion control circuit is connected to the second input end of the subtraction circuit and also connected to the second input end of the addition circuit; The first input terminal of the subtraction circuit and the first input terminal of the addition circuit are both connected to the first input terminal of the adaptive frequency conversion control unit; The output end of the subtraction circuit and the output end of the addition circuit are respectively the first output end and the second output end of the adaptive frequency conversion control unit; The first input end of the signal modulation unit is connected to the output end of the adaptive frequency conversion control unit, and the second input end is connected to the output end of the power amplifier; the signal modulation unit is used to modulate the output signal of the adaptive frequency conversion control unit into a high-frequency carrier signal; The input end of the logic processing unit is connected to the output end of the signal modulation unit to realize high-frequency carrier signal latching and level conversion; The input end of the signal demodulation unit is connected to the output end of the logic processing unit, and is used to filter out the high-frequency component in the high-frequency carrier signal and output the signal to the output end of the power amplifier.

2. The cascaded dual-control class D power amplifier based on adaptive frequency conversion as claimed in claim 1, characterized in that: The error integration unit includes an operational amplifier D2B, a capacitor C1 and a resistor R5. The first input terminal of the error integration unit is connected to the inverting input terminal of the operational amplifier D2B through the resistor R5, and the inverting input terminal of the operational amplifier D2B is also connected to the output terminal of the operational amplifier D2B through the capacitor C1; the non-inverting input terminal of the operational amplifier D2B is the second input terminal of the error integration unit, and the output terminal of the operational amplifier D2B is the output terminal of the error integration unit.

3. The cascaded dual-control class D power amplifier based on adaptive frequency conversion as claimed in claim 1, characterized in that: The adaptive frequency conversion control circuit includes a resistor R7, a resistor R10, a capacitor C2, a resistor C4 and an operational amplifier D5B; The input end of the adaptive frequency conversion control circuit is connected to the non-inverting input end of the operational amplifier D5B through the resistor R7, and the non-inverting input end of the operational amplifier D5B is also grounded through the capacitor C2; the inverting input end of the operational amplifier D5B is connected to the output end of the operational amplifier D5B through the resistor R10, and the capacitor C4 is connected in parallel with the resistor R10; the output end of the operational amplifier D5B is the output end of the adaptive frequency conversion control circuit.

4. The cascaded dual-control class D power amplifier based on adaptive frequency conversion as claimed in claim 1, characterized in that: The subtraction circuit includes a resistor R1, a resistor R2, a resistor R3, a resistor R6 and an operational amplifier D1B; The first input terminal of the subtraction circuit is connected to the non-inverting input terminal of the operational amplifier D1B through the resistor R2, and the non-inverting input terminal of the operational amplifier D1B is also grounded through the resistor R1; the second input terminal of the subtraction circuit is connected to the inverting input terminal of the operational amplifier D1B through the resistor R3, and the inverting input terminal of the operational amplifier D1B is also connected to the output terminal of the operational amplifier D1B through the resistor R6; the output terminal of the operational amplifier D1B is the output terminal of the subtraction circuit.

5. The cascaded dual-control class D power amplifier based on adaptive frequency conversion as claimed in claim 1, characterized in that: The adding circuit includes a resistor R8, a resistor R11, a resistor R12, a resistor R13 and an operational amplifier D6B; The first input terminal of the adding circuit is connected to the non-inverting input terminal of the operational amplifier D6B through a resistor R8, the second input terminal of the adding circuit is connected to the non-inverting input terminal of the operational amplifier D6B through a resistor R11, the inverting input terminal of the operational amplifier D6B is grounded through a resistor R12, and is also connected to the output terminal of the operational amplifier D6B through a resistor R13; the output terminal of the operational amplifier D6B is the output terminal of the adding circuit.

6. The cascaded dual-control class D power amplifier based on adaptive frequency conversion as claimed in claim 1, characterized in that: The first input end of the signal modulation unit includes a first sub-input end and a second sub-input end connected to the first output end and the second output end of the adaptive frequency conversion control unit respectively; The signal modulation unit includes a voltage comparator D3 and a voltage comparator D4; the non-inverting input terminal of the voltage comparator D3 and the inverting input terminal of the voltage comparator D4 are respectively the first sub-input terminal and the second sub-input terminal of the signal modulation unit; The inverting input terminal of the voltage comparator D3 and the non-inverting input terminal of the voltage comparator D4 are simultaneously connected to the second input terminal of the signal modulation unit; The output terminal of the voltage comparator D3 and the output terminal of the voltage comparator D4 are respectively the first output terminal and the second output terminal of the signal modulation unit.

7. The cascaded dual-control class D power amplifier based on adaptive frequency conversion as claimed in claim 6, characterized in that: The logic processing unit includes a NOR gate circuit D7B and a NOR gate circuit D4B, and also includes a resistor R4 and a resistor R9; The first input end of the NOR gate circuit D7B is connected to the second output end of the signal modulation unit, and is also connected to the positive pole of the power supply through the resistor R4; the output end of the NOR gate circuit D7B is connected to the second input end of the NOR gate circuit D4B; the first input end of the NOR gate circuit D4B is connected to the first output end of the signal modulation unit, and is also connected to the positive pole of the power supply through the resistor R9; the output end of the NOR gate circuit D4B is connected to the second input end of the NOR gate circuit D7B; the output end of the NOR gate circuit D4B is the output end of the logic processing unit.

8. The cascaded dual-control class D power amplifier based on adaptive frequency conversion according to any one of claims 1 to 7, characterized in that: The signal demodulation unit includes a field effect transistor V1, a field effect transistor V2, an inductor L1 and a capacitor C3; The gate of the field effect tube V1 and the gate of the field effect tube V2 are both connected to the input end of the signal demodulation unit; the drain of the field effect tube V1 is connected to the positive power supply VS+, the source is connected to the drain of the field effect tube V2, and the source of the field effect tube V2 is connected to the negative power supply VS-; The source of the field effect transistor V1 is also connected to the output end of the signal demodulation unit through the inductor L1 , and the output end of the signal demodulation unit is also grounded through the capacitor C3 .

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