Capacitance multiplexing circuit for D-class and AB-class audio power amplifiers

Abstract

The invention discloses a capacitor multiplexing circuit for class D and class AB audio power amplifiers, which comprises a class D amplifier loop integrator, a class AB amplifier output circuit and a plurality of groups of switches, and is characterized in that the class D amplifier loop integrator comprises an operational amplifier U1, a positive end integral element and a negative end integral element; the AB-class amplifier output circuit comprises an AB-class amplifier positive end output stage circuit and an AB-class amplifier negative end output stage circuit, and the plurality of groups of switches comprise a first switch group, a second switch group, a third switch group and a fourth switch group. According to the capacitor multiplexing circuit of the class-D and class-AB audio power amplifiers, the problems that in an existing chip integrating class-AB and class-D power amplifiers, the occupied area of the capacitors is large, and cost is high are solved, efficient multiplexing of the capacitors in the two modes is achieved, and meanwhile it is guaranteed that the working performance of the class-D and class-AB modes is not affected.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of audio power amplifier, and particularly relates to a capacitor multiplexing circuit of a D-class and AB-class audio power amplifier. BACKGROUND

[0002] The existing audio power amplifier chip usually integrates the AB-class audio power amplifier and the D-class audio power amplifier in the same integrated circuit, realizes free switching of the two modes through a control logic, and multiplexes a large-size output power tube in the two modes, and only works in one mode at the same time. However, the AB-class amplifier and the D-class amplifier usually need to be provided with a large-size capacitor (such as an integrator capacitor of the D-class amplifier and a compensation capacitor of the AB-class amplifier) inside the circuit, and these capacitors occupy a large chip area, resulting in high chip cost, which is not conducive to the miniaturization and low-cost demand of the product. SUMMARY

[0003] The main purpose of the application is to provide a capacitor multiplexing circuit of a D-class and AB-class audio power amplifier, solve the problem of large capacitor area and high cost in the existing chip integrating the AB-class and D-class power amplifier, realize efficient multiplexing of the capacitor in the two modes, and ensure that the working performance of the D-class and AB-class modes is not affected.

[0004] To achieve the above purpose, the application provides a capacitor multiplexing circuit of a D-class and AB-class audio power amplifier, which comprises a D-class amplifier loop integrator, an AB-class amplifier output circuit and a plurality of groups of switches, wherein: The D-class amplifier loop integrator comprises an operational amplifier U1, a positive end integrating element and a negative end integrating element, wherein: The negative input end of the operational amplifier U1 is connected with an audio input negative end IN_N, and the positive input end of the operational amplifier U1 is connected with an audio input positive end IN_P, the negative output end of the operational amplifier U1 serves as an audio output negative end INT_OUTN, and the positive output end of the operational amplifier U1 serves as an audio output positive end INT_OUTP; The AB-class amplifier output circuit comprises an AB-class amplifier positive end output stage circuit and an AB-class amplifier negative end output stage circuit, the AB-class amplifier positive end output stage circuit comprises a positive end output power tube group, a positive end output high end zeroing resistor and compensation capacitor group and a positive end output low end zeroing resistor and compensation capacitor group, and the AB-class amplifier negative end output stage circuit comprises a negative end output power tube group, a negative end output high end zeroing resistor and compensation capacitor group and a negative end output low end zeroing resistor and compensation capacitor group; The multiple groups of switches comprise a first group of switches, a second group of switches, a third group of switches and a fourth group of switches, the negative input end and the positive output end of the operational amplifier U1 are connected to the positive end output stage circuit of the AB class amplifier through the first group of switches and the second group of switches, and the positive input end and the negative output end of the operational amplifier U1 are connected to the negative end output stage circuit of the AB class amplifier through the third group of switches and the fourth group of switches; In the D class working mode, the first group of switches and the third group of switches are in the closed state and the second group of switches and the fourth group of switches are in the open state, the related capacitances of the positive end integral element and the negative end integral element are used as the integrator capacitances by the D class amplifier, and the corresponding switches are arranged at the output ends of the AB class amplifier positive end output stage circuit and the AB class amplifier negative end output stage circuit, respectively, for isolating the voltage overshoot and the glitch of the output end and the signal interference of the D class amplifier loop integrator through the corresponding positive end output power tube group and the negative end output power tube group; In the AB class working mode, the first group of switches and the third group of switches are in the open state and the second group of switches and the fourth group of switches are in the closed state, the related capacitances of the positive end integral element and the negative end integral element are used as the compensation capacitances by the AB class amplifier.

[0005] As a further preferred technical solution of the above technical solution, the positive end integral element comprises capacitors C5P-C10P and a resistor R3P, and the first group of switches comprises switches S10P-S17P, wherein: The switches S12P, the capacitor C7P, the switch S16P, the switch S15P, the capacitor C10P and the switch S17P are sequentially connected between the negative input end and the positive output end of the operational amplifier U1, and the common connection end of the switch S16P and the switch S15P is grounded through the resistor R3P; The switch S11P and the capacitor C6P in series connection are connected in parallel between one end of the switch S12P close to the negative input end of the operational amplifier U1 and one end of the capacitor C7P away from the switch S12P, and the switch S10P and the capacitor C5P in series connection are also connected in parallel; The switch S14P and the capacitor C9P in series connection are connected in parallel between one end of the switch S15P close to the negative input end of the operational amplifier U1 and one end of the capacitor C10P away from the switch S15P, and the switch S13P and the capacitor C8P in series connection are also connected in parallel.

[0006] As a further preferred technical solution of the above technical solution, the negative end integral element comprises capacitors C5N-C10N and a resistor R3N, and the third group of switches comprises switches S10N-S17N, wherein: The positive input terminal and the negative output terminal of the operational amplifier U1 are connected in sequence by a switch S12N, a capacitor C7N, a switch S16N, a switch S15N, a capacitor C10N, and a switch S17N, and the common terminal of switches S16N and S15N is grounded through a resistor R3N. A series switch S11N and a capacitor C6N are connected in parallel between the end of switch S12N closest to the positive input terminal of operational amplifier U1 and the end of capacitor C7N furthest from switch S12N, and a series switch S10N and a capacitor C5N are connected in parallel. A series switch S14N and a capacitor C9N are connected in parallel between the end of switch S15N closest to the positive input terminal of operational amplifier U1 and the end of capacitor C10N furthest from switch S15N. A series switch S13N and a capacitor C8N are also connected in parallel.

[0007] As a further preferred embodiment of the above technical solution, for the positive output stage circuit of the Class AB amplifier, the positive output power transistor group includes field-effect transistors Q1P and Q2P, the positive output high-side zero-adjustment resistor and compensation capacitor group includes resistor R1P, capacitor C1P, and capacitor C2P, the positive output low-side zero-adjustment resistor and compensation capacitor group includes resistor R2P, capacitor C3P, and capacitor C4P, and the second switch group includes switches S1P to S9P, wherein: The common terminal of switch S10P and capacitor C5P is connected to one end of switch S4P; the common terminal of switch S13P and capacitor C8P is connected to one end of switch S5P; the common terminal of switch S12P and capacitor C7P is connected to one end of switch S6P; the common terminal of switch S15P and capacitor C10P is connected to one end of switch S7P; the ends of capacitors C5P, C6P, and C7P furthest from their respective connected switches are all connected to one end of switch S8P; the ends of capacitors C8P, C9P, and C10P furthest from their respective connected switches are all connected to one end of switch S9P. One end of switch S1P is connected to the input terminal PG_P and the gate of the field-effect transistor Q1P. The other end of switch S1P is connected to the other end of switch S4P, the other end of switch S5P, one end of capacitor C1P, and one end of capacitor C2P through resistor R1P. One end of switch S2P is connected to the input terminal NG_P and the gate of the field-effect transistor Q2P. The other end of switch S2P is connected to the other end of switch S6P, the other end of switch S7P, one end of capacitor C3P, and one end of capacitor C4P through resistor R2P. One end of switch S3P is connected with the other end of capacitor C1P, the other end of capacitor C2P, the other end of capacitor C3P, the other end of capacitor C4P, the other end of switch S8P and the other end of capacitor S9P respectively, and the other end of switch S3P is connected with the drain of field effect tube Q1P, the drain of field effect tube Q2P and output end OUT_P respectively.

[0008] As a further preferred technical solution of the above technical solution, for the negative terminal output stage circuit of the AB class amplifier, the negative terminal output power tube group comprises field effect tube Q1N and field effect tube Q2N, the negative terminal output high end zero setting resistance and compensation capacitor group comprises resistance R1N, capacitor C1N and capacitor C2N, the negative terminal output low end zero setting resistance and compensation capacitor group comprises resistance R2N, capacitor C3N and capacitor C4N, and the fourth switch group comprises S1N-S9N, wherein: The common connection end of switch S10N and capacitor C5N is connected with one end of switch S4N, the common connection end of switch S13N and capacitor C8N is connected with one end of switch S5N, the common connection end of switch S12N and capacitor C7N and one end of switch S6N are connected, and the common connection end of switch S15N and capacitor C10N and one end of switch S7N are connected; one end of capacitor C5N, capacitor C6N and capacitor C7N away from the switch connected with each other is connected with one end of switch S8N, and one end of capacitor C8N, capacitor C9N and capacitor C10N away from the switch connected with each other is connected with one end of switch S9N; One end of switch S1N is connected with input end PG_N and the gate of field effect tube Q1N respectively, and the other end of switch S1N is connected with the other end of switch S4N, the other end of switch S5N, one end of capacitor C1N and one end of capacitor C2N through resistance R1N respectively; one end of switch S2N is connected with input end NG_N and the gate of field effect tube Q2N respectively, and the other end of switch S2N is connected with the other end of switch S6N, the other end of switch S7N, one end of capacitor C3N and one end of capacitor C4N through resistance R2N respectively; One end of switch S3N is connected with the other end of capacitor C1N, the other end of capacitor C2N, the other end of capacitor C3N, the other end of capacitor C4N, the other end of switch S8N and the other end of capacitor S9N respectively, and the other end of switch S3N is connected with the drain of field effect tube Q1N, the drain of field effect tube Q2N and output end OUT_N respectively.

[0009] The beneficial effects of the present application are as follows: 1. Cost and area optimization: by reusing the capacitor group, the number and total size of the independently set capacitors of the class D amplifier and the class AB amplifier are reduced, the chip area is significantly reduced, the chip manufacturing cost is reduced, and the market demand for small size and low cost of audio power amplifier chips is met.

[0010] 2. Performance guarantee: through the isolation effect of switches (S3P, S3N, S1P~S2P, S1N~S2N), the output end power switch signal with voltage glitch in class D mode is prevented from being misdirected through the channel or body diode of switch group mos (S4P~S9P, S4N~S9N) to interfere with the integrator and capacitor signal; at the same time, the access paths of the multiplexed capacitor groups in the two modes are independent, and different performance requirements can be adapted through parameter adjustment, ensuring that the working performance of class D and class AB modes (such as the integral parameters of class D and their corresponding loop gain, loop bandwidth, loop phase margin, the phase margin and output stability of class AB) are not affected.

[0011] 3. Flexibility and compatibility: the circuit supports flexible adjustment of integrator type (first order, second order, multi-stage cascade), amplifier type (fully differential, single-ended), capacitor type (polarity, no polarity), and switch structure, which can adapt to different specifications of audio power amplifier chip design and has strong compatibility. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is the circuit diagram of the present application.

[0013] Figure 2 is the circuit diagram of the present application (the circuit structure is consistent with Figure 1 , the difference is that the multiplexed capacitor uses a double-layer polysilicon capacitor or a metal capacitor without polarity, which is suitable for circuit scenarios without requirements for capacitor polarity). DETAILED DESCRIPTION

[0014] The following description is used to disclose the present application so that those skilled in the art can implement the present application. The preferred embodiments in the following description are only as examples, and other obvious modifications can be thought of by those skilled in the art. The basic principles of the present application defined in the following description can be applied to other embodiments, modifications, improvements, equivalents and other technical solutions without departing from the spirit and scope of the present application.

[0015] The present application discloses a capacitor multiplexing circuit for class D and class AB audio power amplifier, and the specific embodiments of the application are further described below in conjunction with preferred embodiments.

[0016] In the embodiments of the present application, those skilled in the art should note that the capacitors and resistors involved in the present application can be regarded as prior art.

[0017] Preferred embodiments.

[0018] As Figure 1 shown, the present application discloses a capacitor multiplexing circuit for class D and class AB audio power amplifier, which comprises a class D amplifier loop integrator, an AB amplifier output circuit and a plurality of groups of switches. The D-class amplifier loop integrator comprises an operational amplifier U1, a positive terminal integral element and a negative terminal integral element, wherein: The negative input terminal of the operational amplifier U1 is connected with the audio input negative terminal IN_N and the positive input terminal of the operational amplifier U1 is connected with the audio input positive terminal IN_P, the negative output terminal of the operational amplifier U1 is used as the audio output negative terminal INT_OUTN and the positive output terminal of the operational amplifier U1 is used as the audio output positive terminal INT_OUTP; The AB-class amplifier output circuit comprises an AB-class amplifier positive terminal output stage circuit and an AB-class amplifier negative terminal output stage circuit, the AB-class amplifier positive terminal output stage circuit comprises a positive terminal output power tube group, a positive terminal output high-end zeroing resistance and compensation capacitor group and a positive terminal output low-end zeroing resistance and compensation capacitor group, and the AB-class amplifier negative terminal output stage circuit comprises a negative terminal output power tube group, a negative terminal output high-end zeroing resistance and compensation capacitor group and a negative terminal output low-end zeroing resistance and compensation capacitor group; The multiple switch groups comprise a first switch group, a second switch group, a third switch group and a fourth switch group, the negative input terminal and the positive output terminal of the operational amplifier U1 are connected with the AB-class amplifier positive terminal output stage circuit through the first switch group and the second switch group, and the positive input terminal and the negative output terminal of the operational amplifier U1 are connected with the AB-class amplifier negative terminal output stage circuit through the third switch group and the fourth switch group; In the D-class working mode, the first switch group and the third switch group are in the closed state and the second switch group and the fourth switch group are in the open state, the related capacitors of the positive terminal integral element and the related capacitors of the negative terminal integral element are used as integrator capacitors by the D-class amplifier, and corresponding switches are arranged at the output terminals of the AB-class amplifier positive terminal output stage circuit and the AB-class amplifier negative terminal output stage circuit, which are respectively used for isolating the voltage overshoot and the glitch of the output terminals and the signal interference of the D-class amplifier loop integrator through the corresponding positive terminal output power tube group and the negative terminal output power tube group; In the AB-class working mode, the first switch group and the third switch group are in the open state and the second switch group and the fourth switch group are in the closed state, the related capacitors of the positive terminal integral element and the related capacitors of the negative terminal integral element are used as compensation capacitors by the AB-class amplifier.

[0019] Specifically, the positive terminal integral element comprises capacitors C5P-C10P and a resistor R3P, and the first switch group comprises switches S10P-S17P, wherein: The switch S12P, the capacitor C7P, the switch S16P, the switch S15P, the capacitor C10P and the switch S17P are sequentially connected between the negative input terminal and the positive output terminal of the operational amplifier U1, and the common connection terminals of the switch S16P and the switch S15P are grounded through the resistor R3P; Switch S12P has switch S11P and capacitor C6P connected in series in parallel between one end close to the negative input terminal of operational amplifier U1 and one end of capacitor C7P away from switch S12P, and has switch S10P and capacitor C5P connected in series in parallel. Switch S15P has switch S14P and capacitor C9P connected in series in parallel between one end close to the negative input terminal of operational amplifier U1 and one end of capacitor C10P away from switch S15P, and has switch S13P and capacitor C8P connected in series in parallel.

[0020] More specifically, the negative terminal integration element comprises capacitor C5N-capacitor C10N, resistor R3N, and the third switch group comprises switch S10N-switch S17N, wherein: The positive input terminal and the negative output terminal of operational amplifier U1 are connected in sequence with switch S12N, capacitor C7N, switch S16N, switch S15N, capacitor C10N and switch S17N, and the common connection end of switch S16N and switch S15N is connected to ground through resistor R3N; Switch S12N has switch S11N and capacitor C6N connected in series in parallel between one end close to the positive input terminal of operational amplifier U1 and one end of capacitor C7N away from switch S12N, and has switch S10N and capacitor C5N connected in series in parallel. Switch S15N has switch S14N and capacitor C9N connected in series in parallel between one end close to the positive input terminal of operational amplifier U1 and one end of capacitor C10N away from switch S15N, and has switch S13N and capacitor C8P connected in series in parallel.

[0021] Further, for the positive terminal output stage circuit of the AB class amplifier, the positive terminal output power tube group comprises field effect tube Q1P and field effect tube Q2P, the positive terminal output high end zeroing resistor and compensation capacitor group comprises resistor R1P, capacitor C1P and capacitor C2P, the positive terminal output low end zeroing resistor and compensation capacitor group comprises resistor R2P, capacitor C3P and capacitor C4P, and the second switch group comprises S1P-switch S9P, wherein: The common connection end of switch S10P and capacitor C5P is connected to one end of switch S4P, the common connection end of switch S13P and capacitor C8P is connected to one end of switch S5P, the common connection end of switch S12P and capacitor C7P is connected to one end of switch S6P, and the common connection end of switch S15P and capacitor C10P is connected to one end of switch S7P; one end of capacitor C5P, capacitor C6P and capacitor C7P away from the switch connected to each other is connected to one end of switch S8P, and one end of capacitor C8P, capacitor C9P and capacitor C10P away from the switch connected to each other is connected to one end of switch S9P; One end of switch S1P is connected with input end PG_P and gate of field effect transistor Q1P respectively, the other end of switch S1P is connected with the other end of switch S4P, the other end of switch S5P, one end of capacitor C1P and one end of capacitor C2P through resistor R1P respectively; one end of switch S2P is connected with input end NG_P and gate of field effect transistor Q2P respectively, the other end of switch S2P is connected with the other end of switch S6P, the other end of switch S7P, one end of capacitor C3P and one end of capacitor C4P through resistor R2P respectively; One end of switch S3P is connected with the other end of capacitor C1P, the other end of capacitor C2P, the other end of capacitor C3P, the other end of capacitor C4P, the other end of switch S8P and the other end of capacitor S9P respectively, the other end of switch S3P is connected with drain of field effect transistor Q1P, drain of field effect transistor Q2P and output end OUT_P respectively.

[0022] Further, for the AB class amplifier negative end output stage circuit, the negative end output power tube group includes field effect transistor Q1N and field effect transistor Q2N, the negative end output high end zeroing resistance and compensation capacitor group includes resistor R1N, capacitor C1N and capacitor C2N, the negative end output low end zeroing resistance and compensation capacitor group includes resistor R2N, capacitor C3N and capacitor C4N, the fourth switch group includes S1N-S9N, wherein: The common connection end of switch S10N and capacitor C5N is connected with one end of switch S4N, the common connection end of switch S13N and capacitor C8N is connected with one end of switch S5N, the common connection end of switch S12N and capacitor C7N and one end of switch S6N are connected, the common connection end of switch S15N and capacitor C10N and one end of switch S7N are connected; one end of capacitor C5N, capacitor C6N and capacitor C7N away from the end of the switch connected with one end of switch S8N, one end of capacitor C8N, capacitor C9N and capacitor C10N away from the end of the switch connected with one end of switch S9N; One end of switch S1N is connected with input end PG_N and gate of field effect transistor Q1N respectively, the other end of switch S1N is connected with the other end of switch S4N, the other end of switch S5N, one end of capacitor C1N and one end of capacitor C2N through resistor R1N respectively; one end of switch S2N is connected with input end NG_N and gate of field effect transistor Q2N respectively, the other end of switch S2N is connected with the other end of switch S6N, the other end of switch S7N, one end of capacitor C3N and one end of capacitor C4N through resistor R2N respectively; One end of switch S3N is connected with the other end of capacitor C1N, the other end of capacitor C2N, the other end of capacitor C3N, the other end of capacitor C4N, the other end of switch S8N and the other end of capacitor S9N respectively, and the other end of switch S3N is connected with the drain of field effect tube Q1N, the drain of field effect tube Q2N and output terminal OUT_N respectively.

[0023] For the present application, as Figure 1 shown in the figure, the capacitors use complementary poly-nwell well capacitors with positive and negative properties, and the circuit mainly multiplexes the integrator capacitors of the class-D audio amplifier and the compensation capacitors of the class-AB audio amplifier, wherein: U1 is a full-differential operational amplifier in the integrator of the full-differential class-D amplifier, IN_N and IN_P are the negative and positive audio inputs of the integrator, INT_OUTP and INT_OUTN are the positive and negative audio outputs of the integrator, C5P, C6P, C7P, C8P, C9P, C10P, R3P circuit constitutes the positive end integration element of the second-order integrator, and C5N, C6N, C7N, C8N, C9N, C10N, R3N circuit constitutes the negative end integration element of the second-order integrator.

[0024] The virtual frame is the positive and negative output stage circuit of the class-AB amplifier, wherein Q1P and Q2P constitute the positive output power tube group, Q1N and Q2N constitute the negative output power tube group, R1P, C1P and C2P are the positive output high-end zeroing resistance and compensation capacitor group, R2P, C3P and C4P are the positive output low-end zeroing resistance and compensation capacitor group, R1N, C1N and C2N are the negative output high-end zeroing resistance and compensation capacitor group, and R2N, C3N and C4N are the negative output low-end zeroing resistance and compensation capacitor group.

[0025] In the class-D working mode, the on and off states of the switches are as Figure 1 shown in the figure, that is, S10P, S11P, S12P, S13P, S14P, S15P, S16P, S17P and S10N, S11N, S12N, S13N, S14N, S15N, S16N, S17N are in the closed state, and the rest S1P, S2P, S3P, S4P, S5P, S6P, S7P, S8P, S9P and S1N, S2N, S3N, S4N, S5N, S6N, S7N, S8N, S9N are in the open state, and capacitors C5P, C7P, C8P, C10P and C5N, C7N, C8N, C10N are used as integrator capacitors by the class-D amplifier. Among them, switches S3P and S3N isolate the signal interference of the output voltage overshoot and glitch through the switch mos tube on the class-D integrator and well capacitor.

[0026] Conversely, in AB class operating modes, the on and off states of the switch are the same as... Figure 1 Conversely, S10P, S11P, S12P, S13P, S14P, S15P, S16P, S17P and S10N, S11N, S12N, S13N, S14N, S15N, S16N, S17N are in the open state, while the remaining S1P, S2P, S3P, S4P, S5P, S6P, S7P, S8P, S9P and S1N, S2N, S3N, S4N, S5N, S6N, S7N, S8N, S9N are in the closed state. Capacitors C5P, C7P, C8P, C10P and C5N, C7N, C8N, C10N are used as compensation capacitors by the Class AB amplifier.

[0027] Furthermore, the circuit implements a capacitor reuse scheme for Class D and Class AB amplifiers. Depending on the specific circuit parameters, only a portion of the integrator capacitors can be used for reuse, or only a portion of the compensation capacitors can be used for reuse; or... Figure 1 In a Class AB amplifier, the compensation capacitors C1P, C2P, C1N, and C2N can have zero values, or in a Class D amplifier, the integrator capacitors C6P, C9P, C6N, and C9N can have zero values.

[0028] It is worth mentioning that, for example, besides Figure 1 The reuse of Class D second-order integrator capacitors and Class AB compensation capacitors can also be implemented as a reuse of Class D first-order integrator capacitors and Class AB compensation capacitors, a reuse of Class D multi-stage cascaded integrator capacitors and Class AB compensation capacitors, a reuse of compensation capacitors and Class AB compensation capacitors in a Class D operational amplifier, or a reuse of filter / delay capacitors and Class AB compensation capacitors in a Class D operational amplifier. The Class AB compensation circuit and its position in the circuit can also have other structures and locations.

[0029] In addition to the fully differential amplifier form mentioned above, it can also be a single-ended amplifier form.

[0030] In addition to the trap capacitors with positive and negative polarities mentioned above, double-layer polysilicon capacitors or metal capacitors without positive or negative polarities can also be used. For specific circuit implementation methods, please refer to [reference needed]. Figure 2 .

[0031] It is worth mentioning that the technical features such as capacitors and resistors involved in this patent application should be regarded as prior art. The specific structure, working principle, and possible control methods and spatial arrangement of these technical features can be adopted using conventional choices in the field, and should not be regarded as the inventive point of this patent. This patent will not be further elaborated in detail.

[0032] Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A capacitor multiplexing circuit for Class D and Class AB audio power amplifiers, characterized in that, Includes a Class D amplifier loop integrator, a Class AB amplifier output circuit, and multiple sets of switches, among which: The Class D amplifier loop integrator includes operational amplifier U1, a positive-terminal integrator, and a negative-terminal integrator, wherein: The negative input terminal of the operational amplifier U1 is connected to the negative audio input terminal IN_N, and the positive input terminal of the operational amplifier U1 is connected to the positive audio input terminal IN_P. The negative output terminal of the operational amplifier U1 is used as the negative audio output terminal INT_OUTN, and the positive output terminal of the operational amplifier U1 is used as the positive audio output terminal INT_OUTP. The Class AB amplifier output circuit includes a positive output stage circuit and a negative output stage circuit. The positive output stage circuit includes a positive output power transistor group, a positive output high-side zero-adjustment resistor and compensation capacitor group, and a positive output low-side zero-adjustment resistor and compensation capacitor group. The negative output stage circuit includes a negative output power transistor group, a negative output high-side zero-adjustment resistor and compensation capacitor group, and a negative output low-side zero-adjustment resistor and compensation capacitor group. The multiple sets of switches include a first switch group, a second switch group, a third switch group, and a fourth switch group. The negative input terminal and the positive output terminal of the operational amplifier U1 are connected to the positive output stage circuit of the Class AB amplifier through the first switch group and the second switch group. The positive input terminal and the negative output terminal of the operational amplifier U1 are connected to the negative output stage circuit of the Class AB amplifier through the third switch group and the fourth switch group. In Class D operating mode, the first and third switch groups are closed and the second and fourth switch groups are open. The relevant capacitors of the positive and negative integrator elements are used as integrator capacitors by the Class D amplifier. Corresponding switches are set at the output terminals of the positive and negative output stages of the Class AB amplifier to isolate voltage overshoot and glitches from signal interference to the loop integrator of the Class D amplifier through the corresponding positive and negative output power transistor groups. In Class AB operating mode, the first and third switch groups are in the open state and the second and fourth switch groups are in the closed state. The relevant capacitors of the positive terminal integrator and the relevant capacitors of the negative terminal integrator are used as compensation capacitors by the Class AB amplifier.

2. The capacitor multiplexing circuit for a Class D and Class AB audio power amplifier according to claim 1, characterized in that, The positive terminal integrating element includes capacitors C5P-C10P and resistor R3P, and the first switch group includes switches S10P-S17P, wherein: The negative input terminal and positive output terminal of the operational amplifier U1 are connected in sequence by a switch S12P, a capacitor C7P, a switch S16P, a switch S15P, a capacitor C10P, and a switch S17P, and the common terminal of switches S16P and S15P is grounded through a resistor R3P. A series switch S11P and a capacitor C6P are connected in parallel between the end of switch S12P closest to the negative input terminal of operational amplifier U1 and the end of capacitor C7P furthest from switch S12P, and a series switch S10P and a capacitor C5P are connected in parallel. A series switch S14P and a capacitor C9P are connected in parallel between the end of switch S15P closest to the negative input terminal of operational amplifier U1 and the end of capacitor C10P furthest from switch S15P. A series switch S13P and a capacitor C8P are also connected in parallel.

3. The capacitor multiplexing circuit for a Class D and Class AB audio power amplifier according to claim 2, characterized in that, The negative-end integrating element includes capacitors C5N-C10N and resistor R3N, and the third switch group includes switches S10N-S17N, wherein: The positive input terminal and the negative output terminal of the operational amplifier U1 are connected in sequence by a switch S12N, a capacitor C7N, a switch S16N, a switch S15N, a capacitor C10N, and a switch S17N, and the common terminal of switches S16N and S15N is grounded through a resistor R3N. A series switch S11N and a capacitor C6N are connected in parallel between the end of switch S12N closest to the positive input terminal of operational amplifier U1 and the end of capacitor C7N furthest from switch S12N, and a series switch S10N and a capacitor C5N are connected in parallel. A series switch S14N and a capacitor C9N are connected in parallel between the end of switch S15N closest to the positive input terminal of operational amplifier U1 and the end of capacitor C10N furthest from switch S15N. A series switch S13N and a capacitor C8N are also connected in parallel.

4. The capacitor multiplexing circuit for a Class D and Class AB audio power amplifier according to claim 3, characterized in that, For the positive output stage circuit of the Class AB amplifier, the positive output power transistor group includes MOSFETs Q1P and Q2P; the positive output high-side zero-adjustment resistor and compensation capacitor group includes resistor R1P, capacitor C1P, and capacitor C2P; the positive output low-side zero-adjustment resistor and compensation capacitor group includes resistor R2P, capacitor C3P, and capacitor C4P; and the second switch group includes switches S1P to S9P, wherein: The common terminal of switch S10P and capacitor C5P is connected to one end of switch S4P; the common terminal of switch S13P and capacitor C8P is connected to one end of switch S5P; the common terminal of switch S12P and capacitor C7P is connected to one end of switch S6P; the common terminal of switch S15P and capacitor C10P is connected to one end of switch S7P; the ends of capacitors C5P, C6P, and C7P furthest from their respective connected switches are all connected to one end of switch S8P; the ends of capacitors C8P, C9P, and C10P furthest from their respective connected switches are all connected to one end of switch S9P. One end of switch S1P is connected to the input terminal PG_P and the gate of the field-effect transistor Q1P. The other end of switch S1P is connected to the other end of switch S4P, the other end of switch S5P, one end of capacitor C1P, and one end of capacitor C2P through resistor R1P. One end of switch S2P is connected to the input terminal NG_P and the gate of the field-effect transistor Q2P. The other end of switch S2P is connected to the other end of switch S6P, the other end of switch S7P, one end of capacitor C3P, and one end of capacitor C4P through resistor R2P. One end of switch S3P is connected to the other ends of capacitors C1P, C2P, C3P, C4P, switch S8P, and S9P, respectively. The other end of switch S3P is connected to the drain of field-effect transistor Q1P, the drain of field-effect transistor Q2P, and the output terminal OUT_P, respectively.

5. The capacitor multiplexing circuit for a Class D and Class AB audio power amplifier according to claim 4, characterized in that, For the negative output stage circuit of the Class AB amplifier, the negative output power transistor group includes MOSFETs Q1N and Q2N; the negative output high-side zero-adjustment resistor and compensation capacitor group includes resistor R1N, capacitor C1N, and capacitor C2N; the negative output low-side zero-adjustment resistor and compensation capacitor group includes resistor R2N, capacitor C3N, and capacitor C4N; and the fourth switch group includes switches S1N to S9N, wherein: The common terminal of switch S10N and capacitor C5N is connected to one end of switch S4N; the common terminal of switch S13N and capacitor C8N is connected to one end of switch S5N; the common terminal of switch S12N and capacitor C7N is connected to one end of switch S6N; the common terminal of switch S15N and capacitor C10N is connected to one end of switch S7N; the ends of capacitors C5N, C6N, and C7N furthest from their respective connected switches are all connected to one end of switch S8N; the ends of capacitors C8N, C9N, and C10N furthest from their respective connected switches are all connected to one end of switch S9N. One end of switch S1N is connected to the input terminal PG_N and the gate of the field-effect transistor Q1N. The other end of switch S1N is connected to the other end of switch S4N, the other end of switch S5N, one end of capacitor C1N, and one end of capacitor C2N through resistor R1N. One end of switch S2N is connected to the input terminal NG_N and the gate of the field-effect transistor Q2N. The other end of switch S2N is connected to the other end of switch S6N, the other end of switch S7N, one end of capacitor C3N, and one end of capacitor C4N through resistor R2N. One end of switch S3N is connected to the other ends of capacitors C1N, C2N, C3N, C4N, switch S8N, and S9N, respectively. The other end of switch S3N is connected to the drain of field-effect transistor Q1N, the drain of field-effect transistor Q2N, and the output terminal OUT_N, respectively.

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