A power amplifier circuit and an audio device

Abstract

The application provides a power amplifier circuit and an audio device. The power amplifier circuit comprises a first integrator, an input coupling capacitor, a first resistor and a first switch. The first integrator is configured to receive a first signal and output a second signal. The first integrator comprises a first input and a first output. The input coupling capacitor is arranged on the first input. The first resistor is arranged on the first input. The first switch is connected in parallel with the first resistor. The first switch is configured to be turned on when the first signal is enabled as an input, so that the first signal charges the input coupling capacitor. In the application, the first switch is connected in parallel with the first resistor, so that the first switch can be turned on when the first signal is enabled as an input, and the first signal bypasses the first resistor to quickly charge the input coupling capacitor, thereby suppressing the power-on pop sound.

Description

Technical Field

[0001] This application belongs to the field of audio power amplifier technology, and in particular relates to a power amplifier circuit and audio device. Background Technology

[0002] Audio devices, as indispensable electronic terminals in modern life, are widely used in portable speakers, Bluetooth speakers, car audio systems, and other scenarios. Their core performance directly determines the user's listening experience.

[0003] In related technologies, the power amplifier circuit is a key module for amplifying audio signals, but there is a noticeable popping sound during the power-on process of the power amplifier circuit. Summary of the Invention

[0004] The purpose of this application is to provide a power amplifier circuit and audio device, which aims to solve the problem of obvious pop noise in power amplifier circuits in traditional technology.

[0005] A first aspect of this application provides a power amplifier circuit, the power amplifier circuit comprising:

[0006] A first integrator is used to receive a first signal and output a second signal; the first integrator includes a first input terminal and a first output terminal.

[0007] An input coupling capacitor is disposed on the first input terminal;

[0008] The first resistor is set at the first input terminal;

[0009] A first switching element is connected in parallel with the first resistor; the first switching element is configured to be turned on when the first signal initiates the input, so that the first signal charges the input coupling capacitor.

[0010] In some embodiments of this application, the power amplifier circuit further includes:

[0011] A first capacitor, one end of which is electrically connected to the first input terminal, and the other end of which is electrically connected to the first output terminal;

[0012] A second switch, connected in parallel with the first capacitor, is configured to turn on when the first signal initiates the input, thereby connecting the first input terminal and the first output terminal.

[0013] In some embodiments of this application, the power amplifier circuit further includes:

[0014] A second integrator is used to receive a second signal and output a third signal; the second integrator includes a second input terminal and a second output terminal, and the second input terminal is connected to the first output terminal;

[0015] The second capacitor has one end electrically connected to the second input terminal and the other end electrically connected to the second output terminal.

[0016] A third switch, connected in parallel with the second capacitor, is configured to turn on when the first signal initiates the input, thereby connecting the second input terminal and the second output terminal.

[0017] In some embodiments of this application, the first input terminal includes a first positive input terminal and a first negative input terminal, and the first output terminal includes a first positive output terminal and a first negative output terminal;

[0018] The first integrator satisfies at least one of the following:

[0019] A first resistor is provided on the first positive input terminal;

[0020] A first resistor is provided on the first negative input terminal;

[0021] A first capacitor is provided between the first positive input terminal and the first negative output terminal;

[0022] A first capacitor is provided between the first negative input terminal and the first positive output terminal.

[0023] In some embodiments of this application, the second input terminal includes a second positive input terminal and a second negative input terminal, and the second output terminal includes a second positive output terminal and a second negative output terminal;

[0024] The second integrator satisfies at least one of the following:

[0025] A second capacitor is provided between the second positive input terminal and the second negative output terminal;

[0026] A second capacitor is provided between the second negative input terminal and the second positive output terminal.

[0027] In some embodiments of this application, at least one of the first switch, the second switch, and the third switch is a transmission gate.

[0028] In some embodiments of this application, the power amplifier circuit includes a startup control module, which is connected to the input terminal of the first integrator and is used to acquire the first signal and the input voltage signal, and output a first control signal, a second control signal and a common-mode signal based on the first signal and the input voltage signal;

[0029] The first control signal and the second control signal are used to control the on / off state of the first switch, the second switch and the third switch, and the first integrator and the second integrator are used to acquire the common mode signal.

[0030] In some embodiments of this application, the startup control module includes a common-mode voltage generation unit, which includes a first series resistor, a second series resistor, and a third series resistor connected in series. The first series resistor is also used to connect to the input voltage signal, and the third series resistor is also used to ground. A common-mode signal output terminal is provided between the first series resistor and the second series resistor, and the common-mode signal output terminal is used to output the common-mode signal.

[0031] The startup control module further includes a comparator unit, which comprises a first reference current source, a first bias switch, a second bias switch, a third bias switch, a first differential switch, and a second differential switch. The first bias switch and the first reference current source are connected in series, and the first bias switch is also used to connect to the input voltage signal. The first reference current source is also used to ground. The first differential switch and the second differential switch are connected in parallel and then in series with the second bias switch. The first differential switch and the second differential switch are also used to ground. The second bias switch is also used to connect to the input voltage signal. The control electrode of the first differential switch is connected between the second series resistor and the third series resistor, and the control electrode of the second differential switch is used to connect to the first signal. One end of the third bias switch is used to connect to the input voltage signal, and the other end is grounded. The control electrodes of the first bias switch, the second bias switch, and the third bias switch are all connected to the end of the first bias switch connected to the first reference current source.

[0032] The startup control module further includes a delay output unit, which includes a delay module and an inverter. One end of the delay module is connected to the grounded end of the third bias switch, and the other end of the delay module is connected to the inverter. The inverter is used to output the first control signal and the second control signal.

[0033] In some embodiments of this application, the power amplifier circuit further includes a modulation module and an output module. The modulation module is connected to the second integrator and is used to acquire a third signal, and to output a modulation signal after modulating the third signal. The output module is connected to the modulation module and is used to acquire the modulation signal and output a fourth signal according to the modulation signal.

[0034] In some embodiments of this application, the modulation module includes a triangular wave generator, a comparator, and a de-glitch unit. The triangular wave generator is connected to the negative input of the comparator, the positive input of the comparator is used to receive the third signal, and the de-glitch unit is connected to the output of the comparator and to the output module.

[0035] The power amplifier circuit also includes a noise suppression module, which is used to acquire a third signal and a first modulation signal. The first modulation signal is the lowest reference voltage signal of the triangular wave generator. The noise suppression module is used to output a suppression signal to the first input terminal based on the third signal and the first modulation signal.

[0036] In some embodiments of this application, the noise suppression module includes a second reference current source, a first current leakage switch, a second current leakage switch, a third current leakage switch, a fourth current leakage switch, and a fifth current leakage switch; the second reference current source and the first current leakage switch are connected in series, and the second reference current source is also used to connect to an input voltage signal, and the first current leakage switch is also used to ground; the control terminals of the first current leakage switch, the second current leakage switch, the third current leakage switch, the fourth current leakage switch, and the fifth current leakage switch are all connected to the end of the first current leakage switch connected to the second reference current source;

[0037] The noise suppression module further includes a first current source switch and a second current source switch. The first current source switch is connected in series with the second current drain switch. The first current source switch is also used to receive an input voltage signal, and the second current drain switch is also used to ground. The second current source switch is connected in series with the fourth current drain switch, and the second current source switch is also used to receive an input voltage signal. The fourth current drain switch is used to ground. The control terminals of the first current source switch and the second current source switch are connected to the same end of the first current source switch connected to the second current drain switch.

[0038] The noise suppression module further includes a first current mirror unit and a second current mirror unit that are symmetrical to each other. The noise suppression module also includes a first signal input switch, a second signal input switch, and a third signal input switch. The first signal input switch is connected to the first current mirror unit, and the second current source switch, the first signal input switch, and the third current drain switch are connected in series. The third signal input switch is connected to the second current mirror unit, and the second current source switch, the third signal input switch, and the fifth current drain switch are connected in series. The second current source switch, the second signal input switch, and the fourth current drain switch are connected in series.

[0039] The control electrode of the first signal input switch and the control electrode of the third signal input switch are used to connect to the third signal; the second signal input switch is used to connect to the first modulation signal.

[0040] A second aspect of this application also provides an audio device, the audio device including the power amplifier circuit as described above.

[0041] The beneficial effects of the embodiments of the present invention compared with the prior art are as follows: In the above-mentioned power amplifier circuit and audio device, the power amplifier circuit includes a first integrator, an input coupling capacitor, a first resistor, and a first switch; the first integrator is used to receive a first signal to output a second signal; the first integrator includes a first input terminal and a first output terminal; the input coupling capacitor is disposed on the first input terminal; the first resistor is disposed on the first input terminal; the first switch is connected in parallel with the first resistor; the first switch is configured to be turned on when the first signal starts input, so that the first signal charges the input coupling capacitor; in this application, by setting the first switch to be connected in parallel with the first resistor, the first switch can be turned on when the first signal starts input, so that the first signal bypasses the first resistor to achieve rapid charging of the input coupling capacitor, which is beneficial to suppressing power-on pop sound. Attached Figure Description

[0042] Figure 1 A schematic diagram of the circuit structure of a power amplifier circuit provided in an embodiment of this application;

[0043] Figure 2 A schematic diagram of the circuit structure of a power amplifier circuit provided in another embodiment of this application;

[0044] Figure 3 A schematic diagram of the circuit structure of a power amplifier circuit provided in an embodiment of this application;

[0045] Figure 4 A schematic diagram of the circuit structure of a startup control module provided in an embodiment of this application;

[0046] Figure 5A schematic diagram of the circuit structure of a noise suppression module provided in an embodiment of this application;

[0047] Figure 6 This is a schematic diagram of signal changes during the startup process of the power amplifier circuit provided in this embodiment;

[0048] Figure 7 This is a schematic diagram of the signal modulation principle provided in this embodiment;

[0049] Figure 8 This is a schematic diagram showing the effect comparison before and after the introduction of the noise suppression module in this embodiment.

[0050] Specific element symbol explanations: Rin - first resistor, Amp1 - first integrator, Amp2 - second integrator, COMP - comparator, Vcap - first signal, Vcom - common-mode signal, Vmin - first modulation signal, VDD - input voltage signal, Ibias - first reference current source, Ctr_T - first control signal, Ctr_Tn - second control signal, Iref - second reference current source, Cin - input coupling capacitor. Detailed Implementation

[0051] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0052] It should be noted that when a component is referred to as being "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0053] It should be understood that the terms "length", "width", "upper", "lower", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0054] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0055] It's important to know that audio devices, as indispensable electronic terminals in modern life, are widely used in portable speakers, Bluetooth speakers, car audio systems, and other scenarios. Their core performance directly determines the user's listening experience. Among them, the power amplifier circuit, as a key module for amplifying audio signals, must balance high efficiency, high power density, and low noise output to meet the dual requirements of device miniaturization, long battery life, and pure sound quality.

[0056] However, during the power-on process of the power amplifier circuit, the first signal is connected to the integrator through capacitive coupling. Since the bias voltage and common-mode level cannot be established instantaneously, the charging process of the input coupling capacitor is limited by the series resistor, resulting in a slow charging speed. This leads to a transient voltage imbalance between the two channels of the power amplifier, which in turn produces a noticeable pop sound at the speaker end. These problems are difficult to completely solve by traditional external RC delay or digital mute control, and will increase the complexity of peripheral components, affecting the system integration and sound quality consistency.

[0057] Specifically, in related technologies, the input audio signal is coupled through an input capacitor to isolate the DC level and prevent a mismatch between the preamp's sound output and the power amplifier's common-mode level. However, this results in the bias voltage and common-mode level failing to establish instantaneously when the power amplifier powers on or recovers from shutdown mode, causing a transient imbalance between the two channels and resulting in a popping sound at the speaker. Furthermore, when the amplitude of the first signal changes abruptly (such as during song switching, Bluetooth switching, or DAC output transitions), the nodes of the integrator, composed of operational amplifiers, operate at power or ground potential, deviating significantly from normal operation and exceeding the carrier modulation range. When the first signal gradually decreases and returns to normal, the nodes of the integrator begin to re-establish their amplitude. Due to the integrator delay, the integrator output cannot keep up with the rapidly changing first signal, causing a sudden change in the PWM duty cycle of the output stage. This results in overshoot glitches at the output caused by signal establishment, creating noticeable noise in the ear.

[0058] Based on this, this application improves the relevant power amplifier circuit and audio equipment.

[0059] Please see Figure 1 , Figure 1A schematic diagram of the power amplifier circuit provided in this embodiment is shown. The power amplifier circuit of this embodiment includes a first integrator Amp1, an input coupling capacitor Cin, a first resistor Rin, and a first switch. The first integrator Amp1 is used to receive a first signal Vcap to output a second signal. The first integrator Amp1 includes a first input terminal and a first output terminal. The input coupling capacitor Cin is disposed on the first input terminal. The first resistor Rin is disposed on the first input terminal. The first switch is connected in parallel with the first resistor Rin. The first switch is configured to be turned on when the first signal is activated, so that the first signal Vcap charges the input coupling capacitor Cin.

[0060] It needs to be explained that the first integrator, Amp1, is used to perform integration on the input electrical signal, achieving linear transformation and processing of the signal. The first signal, Vcap, is the original audio electrical signal input to the power amplifier circuit, serving as the fundamental signal source for power amplification. The second signal is the electrical signal output after processing by the first integrator, Amp1, providing a suitable signal for subsequent modulation and amplification stages. The first input terminal is the port in the first integrator, Amp1, through which external signals are received; it is the channel for signals to enter the integrator. The first output terminal is the port in the first integrator, Amp1, outputting the processed signal, used to transmit the second signal to the next stage circuit. The input coupling capacitor, Cin, is an electronic component with charge storage and DC blocking / AC passing characteristics, used in circuits to stabilize signals, filter noise, or achieve signal coupling. The first resistor, Rin, is an electronic component with current-impeding characteristics, commonly used in circuits to limit current magnitude, divide voltage, or adjust signal amplitude.

[0061] It is understood that in this embodiment, when the first signal initiates the input, the first switch is turned on according to its configuration, causing the first signal Vcap to bypass the first resistor Rin and charge the input coupling capacitor. This significantly accelerates the charging speed of the input coupling capacitor Cin, allowing the voltage across the capacitor to quickly match the common-mode operating level of the power amplifier. This avoids transient channel imbalance caused by the mismatch between the capacitor voltage and the common-mode level during the power amplifier startup phase, which is beneficial for significantly suppressing power-on pop noise. At the same time, it eliminates the need for additional complex peripheral components, which helps improve system integration and sound quality consistency, and ensures the audio output quality during the power amplifier startup phase.

[0062] In some embodiments of this application, please refer to Figure 2 , Figure 2 A schematic diagram of the power amplifier circuit provided in this embodiment is shown. The power amplifier circuit also includes a first capacitor and a second switch. One end of the first capacitor is electrically connected to the first input terminal, and the other end of the first capacitor is electrically connected to the first output terminal. The second switch is connected in parallel with the first capacitor and is configured to be turned on when the first signal is activated to connect the first input terminal and the first output terminal.

[0063] It is understood that this embodiment uses a second switch and a first capacitor connected in parallel. The second switch is configured to turn on when the first signal is input, thereby connecting the first input terminal and the first output terminal of the first integrator Amp1. During the first signal start-up phase, the first and second switches turn on synchronously, forcing the voltages across the first integrator Amp1 to quickly converge through the direct connection between the first input terminal and the first output terminal. This helps to shorten the state setup time during the integrator start-up phase, reduce signal transmission delay, lay the foundation for the subsequent two-stage integration processing and noise suppression module to work together, and improve the overall signal response speed and operational stability of the power amplifier.

[0064] Please refer to the embodiments described in this application. Figure 2 The power amplifier circuit in this embodiment also includes a second integrator Amp2 and a second capacitor; the second integrator Amp2 is used to receive a second signal and output a third signal; the second integrator Amp2 includes a second input terminal and a second output terminal, the second input terminal is connected to the first output terminal; one end of the second capacitor is electrically connected to the second input terminal, and the other end of the second capacitor is electrically connected to the second output terminal.

[0065] It should be explained that the second integrator, Amp2, is the signal processing unit in the audio amplifier circuit, used to further integrate the electrical signal transmitted from the previous stage. The third signal is the electrical signal output after processing by the second integrator, Amp2, possessing more stable waveform characteristics and providing a suitable input signal for the modulation stage. The second input terminal is the port where the second integrator, Amp2, receives the signal from the previous stage, used to input the second signal output from the first integrator, Amp1. The second output terminal is the port where the second integrator, Amp2, outputs the processed signal, responsible for transmitting the third signal to the modulation stage circuit. The second capacitor is an electronic component with charge storage and signal coupling functions, used to cooperate with the second integrator, Amp2, to complete the signal integration operation and stabilize the circuit's operating state.

[0066] It is understood that in this embodiment, after the second integrator Amp2 receives the second signal output from the first integrator Amp1, it completes secondary integration processing through the synergistic effect with the second capacitor, outputting a stable third signal. This enables multi-stage optimization of the original audio signal, improving its linearity and stability, and providing accurate input for the subsequent modulation stage. Simultaneously, the two-stage integration structure, combined with the noise suppression circuit, helps to further reduce interference during signal transmission, accelerates the recovery speed of the first signal after a sudden change, synergistically suppresses transient noise, and ensures the clarity and consistency of the power amplifier's output audio.

[0067] In some embodiments, please continue reading Figure 2The power amplifier circuit in this embodiment also includes a third switch, which is connected in parallel with the second capacitor. The third switch is configured to be turned on when the first signal is activated to connect the second input terminal and the second output terminal.

[0068] It is understood that in the first signal activation stage of this application embodiment, the first, second, and third switches are synchronously turned on. The first integrator Amp1 achieves direct connection between its input and output terminals through the first and second switches, and the second integrator Amp2 achieves direct connection between its input and output terminals through the third switch. Both integrators form a unity-gain feedback state. This helps to force the voltage across the two integrators to quickly approach the common-mode level, thus enhancing the suppression effect of power-on pop noise.

[0069] Please refer to the embodiments described in this application. Figure 2 In this embodiment, the first input terminal includes a first positive input terminal and a first negative input terminal, and the first output terminal includes a first positive output terminal and a first negative output terminal. A first resistor Rin is disposed on the first positive input terminal. A first resistor Rin is disposed on the first negative input terminal. A first capacitor is disposed between the first positive input terminal and the first negative output terminal.

[0070] In other words, the first switching element is set to two (e.g.) Figure 2 T1 and T2 in the diagram are connected in parallel with the first resistor Rin on the first positive input terminal and the first resistor Rin on the first negative input terminal, respectively. Two second switches are correspondingly configured (e.g., ...). Figure 2 T3 and T4 in the figure are connected in parallel with the two first capacitors, respectively.

[0071] Please refer to the embodiments described in this application. Figure 2 In this embodiment, the second input terminal includes a second positive input terminal and a second negative input terminal, and the second output terminal includes a second positive output terminal and a second negative output terminal. A second capacitor is disposed between the second positive input terminal and the second negative output terminal; conversely, a second capacitor is disposed between the second negative input terminal and the second positive output terminal.

[0072] In other words, the third switch is configured with two (e.g.) Figure 2 T5 and T6 in the middle are connected in parallel with the two second capacitors respectively.

[0073] In some embodiments of this application, please refer to Figure 3 , Figure 3 A schematic diagram of the circuit structure of the power amplifier circuit provided in this embodiment is shown; as follows: Figure 3As shown, C1 and C2 are first capacitors, and C3 and C4 are second capacitors. In this embodiment, at least one of the first, second, and third switching devices is a transmission gate.

[0074] It should be explained that a transmission gate is a bidirectional conductive switching element built on a MOSFET. By adjusting the on or off state with a control signal, bidirectional signal transmission can be achieved. It is often used in analog circuits for precise control of signal paths.

[0075] It is understood that the transmission gate in this embodiment has the characteristics of bidirectional conductivity, low on-resistance, and fast switching speed. This is beneficial to improving the on / off response speed of the switching device, ensuring that the voltage across the integrator quickly approaches the common-mode level during the startup phase, further accelerating capacitor charging efficiency, and enhancing the suppression effect of power-on pop noise. At the same time, the precise control characteristics of the transmission gate can reduce the interference of switching action on the signal, ensuring the integrity of signal transmission under normal working conditions. Combined with the two-stage integrator and noise suppression module, it is beneficial to improve the power amplifier's adaptability to the first signal change, synergistically suppress transient noise, and enhance the overall working stability and audio output quality of the power amplifier.

[0076] Please refer to the embodiments described in this application. Figure 3 The power amplifier circuit of this embodiment includes a startup control module, which is connected to the input terminal of the first integrator Amp1 and is used to acquire the first signal Vcap and the input voltage signal VDD. Based on the first signal Vcap and the input voltage signal VDD, the startup control module outputs a first control signal Ctr_T, a second control signal Ctr_Tn, and a common-mode signal Vcom. The first control signal Ctr_T and the second control signal Ctr_Tn are used to control the on / off of the first switch, the second switch, and the third switch. The first integrator Amp1 and the second integrator Amp2 are used to acquire the common-mode signal Vcom.

[0077] It should be explained that the startup control module is the functional module in the power amplifier circuit responsible for state regulation during the startup phase. It outputs control signals through signal detection and analysis to ensure the stability of the power amplifier's startup process. The input voltage signal VDD is a power supply voltage-related signal connected to the power amplifier circuit during operation, reflecting the circuit's power supply status and voltage level. The first control signal Ctr_T is one of the control signals output by the startup control module, used to regulate the on or off state of the switching components. The second control signal Ctr_Tn is another control signal output by the startup control module, working in conjunction with the first control signal Ctr_T to achieve coordinated control of the switching components. The common-mode signal Vcom is the reference level signal when the power amplifier circuit is operating normally, providing a stable operating level reference for core components such as the integrator.

[0078] It is understood that in this embodiment, the first control signal Ctr_T and the second control signal Ctr_Tn collaboratively control the on / off state of the first, second, and third switching devices. The first integrator Amp1 and the second integrator Amp2 acquire the common-mode signal Vcom as the operating reference. During the first signal startup phase, the control signal drives each switching device to conduct synchronously, connecting the integrator input and output terminals, allowing the signal to bypass the resistor and charge the capacitor. Simultaneously, the common-mode signal Vcom provides a stable reference level for the integrator, facilitating rapid matching of the capacitor voltage with the common-mode level and maximizing the suppression of power-on pop noise. After startup, the control signal drives the switching devices to turn off, and the integrator enters normal operating mode based on the common-mode signal Vcom, ensuring the stability of signal processing. This modular control achieves collaborative operation between the switching devices and the integrator, eliminating the need for additional complex peripheral components, which improves system integration and enhances the accuracy of state control during the startup phase. This lays the foundation for the subsequent transient noise suppression module and enhances the overall audio output quality and operational stability of the power amplifier.

[0079] In some embodiments of this application, please refer to Figure 4 , Figure 4 This embodiment shows a schematic diagram of the circuit structure of the startup control module provided; the startup control module of this embodiment includes a common-mode voltage generation unit, which includes a first series resistor (e.g., ...) connected in series. Figure 4 R1 shown), the second series resistor (as shown) Figure 4 R2 as shown) and the third series resistor (as shown) Figure 4 As shown in R3), the first series resistor is also used to connect the input voltage signal VDD, the third series resistor is also used to ground, and a common-mode signal Vcom output terminal is provided between the first series resistor and the second series resistor. The common-mode signal Vcom output terminal is used to output the common-mode signal Vcom.

[0080] The startup control module also includes a comparator COMP unit, which includes a first reference current source Ibias and a first bias switch (such as...). Figure 4 PM1 shown), the second bias switch (as shown) Figure 4 PM2 shown), third bias switch (as shown) Figure 4 PM3 shown), the first differential switch (as shown) Figure 4 The PM4 shown in the diagram) and the second differential switch (such as PM4) Figure 4(PM5 shown in the diagram); the first bias switch and the first reference current source Ibias are connected in series. The first bias switch is also used to connect to the input voltage signal VDD, and the first reference current source Ibias is also used to ground. The first differential switch and the second differential switch are connected in parallel and then connected in series with the second bias switch. The first differential switch and the second differential switch are also used to ground, and the second bias switch is also used to connect to the input voltage signal VDD. The control electrode of the first differential switch is connected between the second series resistor and the third series resistor. The control electrode of the second differential switch is used to connect to the first signal Vcap. One end of the third bias switch is used to connect to the input voltage signal VDD, and the other end is grounded. The control electrodes of the first bias switch, the second bias switch, and the third bias switch are all connected to the end of the first bias switch connected to the first reference current source Ibias.

[0081] The startup control module also includes a delay output unit, which includes a delay module and an inverter. One end of the delay module is connected to the grounded end of the third bias switch, and the other end of the delay module is connected to the inverter. The inverter is used to output the first control signal Ctr_T and the second control signal Ctr_Tn.

[0082] It is understood that in this embodiment, the first bias switch and the first reference current source Ibias are connected in series to form a bias circuit. The first and second differential switches are connected in parallel and then in series with the second bias switch. The control electrode of the first differential switch is connected to the voltage divider point between the second and third series resistors. The control electrode of the second differential switch is connected to the first signal Vcap. The two ends of the third bias switch are connected to the input voltage signal VDD and ground, respectively. The control electrodes of the three switches are connected to the connection terminal of the first bias switch and the first reference current source Ibias. The delay output unit is connected in series with the inverter through the delay module to output the first and second control signals Ctr_Tn. In this way, the common-mode voltage generation unit can stably output the common-mode signal Vcom, providing an accurate working reference for the integrator. The comparator COMP unit can detect the difference between the first signal Vcap and the voltage divider reference signal in real time and accurately trigger the control logic. The delay output unit can optimize the timing of the control signals to ensure that the first, second, and third switches are turned on and off in an orderly manner. Overall, this is beneficial for achieving fast charging and level matching of the input coupling capacitor and maximizing the suppression of power-on pop noise.

[0083] In some embodiments, the inverter is composed of Figure 4The system consists of PM6 and NM4, forming two output control signals: Ctr_T and Ctr_Tn, used to control the opening and closing of the transmission gate. The first control signal Ctr_T is connected to the positive control terminal of the transmission gate, and the second control signal Ctr_Tn is connected to the negative control terminal. When the positive control signal is high and the negative control signal is low, transmission gates T1-T6 are open; conversely, when the negative control signal is low, transmission gates T1-T6 are closed.

[0084] In some embodiments, the value of Vcom is 0.5VDD, and the voltage at the intermediate node of the second and third series resistors is 0.49VDD. The voltage difference between Vcom and the intermediate node of the second and third series resistors is 0.01VDD.

[0085] Please refer to the embodiments described in this application. Figure 3 The power amplifier circuit in this embodiment also includes a modulation module and an output module. The modulation module is connected to the second integrator Amp2 and is used to acquire a third signal, and output a modulation signal after modulating the third signal. The output module is connected to the modulation module and is used to acquire the modulation signal and output a fourth signal according to the modulation signal.

[0086] It is understood that in this embodiment, the modulation module modulates the stable third signal, converting it into a high-efficiency modulated signal to provide a suitable signal for subsequent power amplification; the output module completes power amplification based on the modulated signal, thereby increasing the signal energy. The modulation module can accurately convert the third signal, ensuring the stability and accuracy of the modulated signal. Combined with the signal optimization effect of the two-stage integrator, it helps to reduce signal distortion during the modulation process. The output module efficiently amplifies the modulated signal, ensuring that the fourth signal has sufficient power to drive the load. At the same time, it works in conjunction with the input bias start-up control module and the transient noise suppression module to further suppress power-on pop noise and input abrupt noise, improve the clarity and fidelity of the audio output, and ensure the overall working efficiency and output quality of the power amplifier.

[0087] In some embodiments, please continue reading Figure 3 The output module consists of a driver unit and a power transistor. The enable signal EnDrv of the driver unit is generated by delaying the transmission gate control signal Ctr_Tn. The output signal is fed back to the input of the first integrator Amp1 through the feedback resistor Rf.

[0088] Please refer to the embodiments described in this application. Figure 3The modulation module in this embodiment includes a triangular wave generator, a comparator COMP, and a de-glitch unit. The triangular wave generator is connected to the negative input of the comparator COMP, the positive input of the comparator COMP is used to receive a third signal, and the de-glitch unit is connected to the output of the comparator COMP and to the output module.

[0089] The power amplifier circuit also includes a noise suppression module, which is used to acquire a third signal and a first modulation signal Vmin. The first modulation signal Vmin is the lowest reference voltage signal of the triangular wave generator. The noise suppression module is used to output a suppression signal to the first input terminal based on the third signal and the first modulation signal Vmin.

[0090] In some embodiments of this application, please refer to Figure 5 , Figure 5 This embodiment shows a schematic diagram of the circuit structure of the noise suppression module provided; the noise suppression module of this embodiment includes a second reference current source Iref, a first current leakage switch (such as... Figure 5 NM1 in the middle), the second current leakage switch (such as NM1), and the second current leakage switch (such as NM1 Figure 5 NM2 in the middle), the third current leakage switch (such as NM2), and the third current leakage switch (such as NM2). Figure 5 NM3 in the middle), the fourth current leakage switch (such as NM3), and the fourth current leakage switch (such as NM3). Figure 5 NM7 in the middle), the fifth current leakage switch (such as NM7 ...) Figure 5 The second reference current source Iref and the first current leakage switch are connected in series, and the second reference current source Iref is also used to connect the input voltage signal VDD, and the first current leakage switch is also used to ground; the control terminals of the first current leakage switch, the second current leakage switch, the third current leakage switch, the fourth current leakage switch, and the fifth current leakage switch are all connected to the end of the first current leakage switch connected to the second reference current source Iref;

[0091] The noise suppression module also includes a first current source switch (such as...) Figure 5 PM1) and the second current source switch (such as PM1) Figure 5 In the configuration of PM2), the first current source switch is connected in series with the second current drain switch. The first current source switch is also used to connect the input voltage signal VDD, and the second current drain switch is also used to ground. The second current source switch is connected in series with the fourth current drain switch, and the second current source switch is also used to connect the input voltage signal VDD. The fourth current drain switch is used to ground. The control electrode of the first current source switch and the control electrode of the second current source switch are connected to the same end of the first current source switch connected to the second current drain switch.

[0092] The noise suppression module also includes a first current mirror unit and a second current mirror unit that are symmetrical to each other, and the noise suppression module also includes a first signal Vcap input switch (such as...). Figure 5 PM7 in the middle), the second signal input switch (such as PM7), and the second signal input switch (such as PM7) Figure 5 PM8 in the middle) and the third signal input switch (such as ... Figure 5 In the PM9 configuration, the first signal Vcap input switch is connected to the first current mirror unit, and the second current source switch, the first signal Vcap input switch, and the third current drain switch are connected in series; the third signal input switch is connected to the second current mirror unit, and the second current source switch, the third signal input switch, and the fifth current drain switch are connected in series; the second current source switch, the second signal input switch, and the fourth current drain switch are connected in series.

[0093] The first signal Vcap input switch and the third signal input switch are used to connect to the third signal; the second signal input switch is used to connect to the first modulation signal Vmin.

[0094] It should be explained that the triangular wave generator is a functional unit in the modulation module used to generate periodic triangular wave signals, providing a reference carrier for signal modulation. The de-glitching unit is an electronic unit used to eliminate spikes and glitches in the signal, improving signal smoothness and stability through filtering or shaping. The noise suppression module is a functional module in the power amplifier circuit used to suppress noise generated by sudden signal changes, achieving noise suppression through signal detection and current regulation.

[0095] Understandably, in this embodiment, the comparator COMP compares the third signal with the triangular wave carrier to generate an initial modulation signal. After the de-glitch unit optimizes the signal quality, it is transmitted to the output module to ensure the stability of the modulation signal. The noise suppression module detects the difference between the third signal and the first modulation signal Vmin through the signal input switch, uses the current leakage switch to buffer current surges, and generates a balanced suppression signal through the symmetrical current mirror unit to regulate the input current of the first integrator Amp1. In this way, the modulation module can output a smooth and stable modulation signal, reducing distortion in the subsequent amplification process. The noise suppression module can respond to the first signal surge in real time, accelerate the establishment of the normal working state of the integrator through current regulation, effectively suppress transient noise, and work with the input bias start-up control module to achieve dual suppression of power-on pop sound and transient noise. At the same time, no additional complex peripheral components are required, which is conducive to maintaining system integration and improving the clarity of the power amplifier's audio output and overall working stability.

[0096] Specifically, the first, second, third, fourth, and fifth current leakage switches constitute the current drain. The third, fourth, and fifth current leakage switches draw current from their respective branches, buffering momentarily established currents and filtering out current spikes. The first and second current source switches constitute the current source. The gates of the first signal input switch (Vcap), second signal input switch, and third signal input switch are connected to the module's three inputs, In1, Vmin, and In2, respectively. Figure 3 In1 and In2 are connected to the positive and negative terminals of the second-stage integrator output, respectively. For example... Figure 5 NM4, NM5, NM6, PM3, PM4, NM9, NM10, NM12, PM5, and PM6 form two sets of symmetrical current mirror structures. The drain of NM6 connected to the drain of PM5 and the drain of NM9 connected to the drain of PM4 form the two outputs Out1 and Out2 of this module. Out1 and Out2 are connected to the input terminals of the first-stage integrator, respectively, to extract and supplement the integrator input current, accelerate the establishment of the working state of each node of the integrator in the power amplifier, and avoid the generation of output noise.

[0097] In the embodiments of this application, please refer to Figures 3 to 5 In the startup control module, the gate of the first differential switch in the comparator COMP unit is connected to the midpoint between the second and third resistors, and the gate of the second differential switch is connected to the input coupling capacitor voltage Vcap. Initially, Vcap is lower than Vcom, so the module outputs a low-level second control signal Ctr_Tn and a high-level first control signal Ctr_T. Transmission gates T1-T6 are open, and the first and second integrators Amp1 and Amp2 are connected in unity-gain feedback configuration. The voltage across Amp1 and Amp2 is forced to the common-mode voltage. Since transmission gates T1 and T2 are open, the first resistor Rin is short-circuited, and the output of the first integrator Amp1 is directly connected to the input coupling capacitor. The output current of the first integrator Amp1 bypasses the first resistor Rin to charge the input coupling capacitor, significantly accelerating its charging speed.

[0098] Please see Figure 6 , Figure 6 The diagram illustrates the signal changes during the startup process of the power amplifier circuit provided in this embodiment; as the input coupling capacitor is continuously charged, the voltage Vcap increases rapidly. At time t1, when the voltage Vcap equals the reference voltage determined by the midpoint between the second and third series resistors, the comparator COMP flips. Figure 4 The drain electrode of NM2 changes from high to low. Figure 4 The drain of NM3 in the amplifier changes from low to high. After the delay of the delay module (time period t1-t2), the first integrator Amp1 and the second integrator Amp2 charge the input coupling capacitor voltage to the common-mode voltage. At time t2, the second control signal Ctr_Tn changes from low to high, the first control signal Ctr_T changes from high to low, the transmission gate closes, and the first integrator Amp1 and the second integrator Amp2 are connected to the normal operating state. After another delay of the delay module located in the driver, that is, time period t2-t3, at time t3, the enable control signal EnDrv of the driver changes from low to high, the driver is turned on, and the entire op-amp begins to work normally. Due to the addition of the start-up control module, the input coupling capacitor voltage Vcap is quickly pulled up to the Vcom level. When the power amplifier is working normally, the voltage at both ends is adjusted to the normal common-mode operating voltage level, avoiding the situation where the voltage difference between the two ends of the power amplifier is large, and suppressing the generation of power-on pop tone to a great extent.

[0099] When the first signal suddenly increases, the output of the second integrator, Amp2, exceeds the modulation range of the carrier. At this time, due to the feedback, each node of the integrator will operate at the power supply or ground potential. When the first signal gradually decreases and returns to normal, the nodes of the integrator begin to re-establish their operating state. Due to the integrator delay of the power amplifier, the integrator output cannot keep up with the rapidly changing first signal. During the re-establishment process of the integrator, due to the continued change of the first signal, at the instant the integrator state is established, the difference between the integrator output and the first signal is large. Therefore, overshoot will occur at each node of the integrator, causing a sudden change in the PWM duty cycle of the output stage. This will produce overshoot glitches at the output caused by signal establishment.

[0100] Please see Figure 7 , Figure 7 This diagram illustrates the signal modulation principle provided in this embodiment; the sine wave in the diagram represents the output of the second-stage integrator. When the first signal at the positive input terminal of the first integrator Amp1 suddenly increases, the negative output terminal of the second integrator Amp2 also increases, exceeding the maximum voltage Vmax of the modulated triangular wave. Due to the fully differential nature of the first signal and the presence of the feedback signal, the positive output terminal of the second integrator Amp2 decreases, falling below the minimum voltage Vmin of the triangular wave. The positive output terminal of the second integrator Amp2 is connected to the In1 input terminal of the noise suppression module. At this time, the voltage at the In1 input terminal is the lowest among the three input terminals, and the current flowing from the second current source switch will flow entirely to the source of the first signal Vcap input switch. After a portion of this current is drawn off by the drain of the third current drain switch, it flows to... Figure 5 NM4 in the middle.

[0101] like Figure 5 NM5 in Figure 5 The current replication of NM4 in the middle is processed by... Figure 5 PM3 and Figure 5 The current mirror composed of PM4 in the middle forms the charging current to OUT2. Figure 5 NM6 in Figure 5 The current mirroring of NM4 in the circuit creates the current draw from Out1. Since the voltage at the right input terminal In2 is much greater than the voltage at the left input terminal In1, there is no current in the right input terminal In2 and the current mirror circuit it forms. By controlling the current mirror ratio, the charging current of Out2 is equal to the drawing current of Out1. Figure 3 As shown, Out1 is connected to the positive input terminal of the first integrator Amp1. The current drawn from Out1 suppresses the increasing trend of the first signal, preventing the negative output terminal of the second integrator Amp2 from continuing to change towards the power supply potential. Out2 is connected to the negative input terminal of the first integrator Amp1. The current drawn from Out2 suppresses the decreasing trend of the first signal, preventing the positive output terminal of the second integrator Amp2 from continuing to change towards ground potential. Therefore, when the signal at the positive input terminal of the first integrator Amp1 changes from large to small, the current drawn from Out1 is superimposed with the current drawn from the first signal. When the signal at the negative input terminal of the first integrator Amp1 changes from small to large, the current drawn from Out2 is superimposed with the current drawn from the first signal, accelerating the establishment process of the integrator's normal operating state and avoiding noise caused by sudden changes in the first signal.

[0102] Under normal operating conditions, the output of the second integrator Amp2 is much greater than the Vmin voltage. The current of the second current source switch flows entirely to the second signal input switch. Out1 and Out2 do not draw or charge current, and will not interfere with the normal operating condition of the power amplifier.

[0103] The third, fourth, and fifth current leakage switches draw a portion of the current from their respective branches. This is done to reduce overshoot caused by current build-up and to eliminate current spikes caused by random glitches in the integrator output. The current drawn by the third, fourth, and fifth current leakage switches is less than the current drawn by the second current source switch.

[0104] Please see Figure 8 , Figure 8 The diagram shows a comparison of the effects before and after the introduction of the noise suppression module provided in this embodiment. Before the noise suppression module was added, glitches would occur when the output signal tended to change normally, that is, when the power supply potential decreased and the ground potential increased. After the module was added, the glitches disappeared, and the noise caused by the sudden change of the first signal was suppressed.

[0105] Furthermore, in order to better implement the power amplifier circuit in any of the above embodiments, based on the power amplifier circuit described above, this application embodiment also provides an audio device, which includes the power amplifier circuit described above.

[0106] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0107] The basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0108] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0109] Similarly, it should be noted that, in order to simplify the description of the present application and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of the embodiments of the present application sometimes combines multiple features into a single embodiment, drawing, or description thereof. However, this disclosure method does not imply that the subject matter of the application requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of the single embodiments disclosed above.

[0110] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A power amplifier circuit, characterized in that, The power amplifier circuit includes: A first integrator is used to receive a first signal and output a second signal; the first integrator includes a first input terminal and a first output terminal. An input coupling capacitor is disposed on the first input terminal; The first resistor is set at the first input terminal; A first switching element is connected in parallel with the first resistor; the first switching element is configured to be turned on when the first signal initiates the input, so that the first signal charges the input coupling capacitor. A first capacitor, one end of which is electrically connected to the first input terminal, and the other end of which is electrically connected to the first output terminal; A second switch is connected in parallel with the first capacitor. The second switch is configured to be turned on when the first signal initiates the input, so as to connect the first input terminal and the first output terminal. A second integrator is used to receive a second signal and output a third signal; the second integrator includes a second input terminal and a second output terminal, and the second input terminal is connected to the first output terminal; The second capacitor has one end electrically connected to the second input terminal and the other end electrically connected to the second output terminal. A third switch, connected in parallel with the second capacitor, is configured to be turned on when the first signal initiates the input, so as to connect the second input terminal and the second output terminal; The power amplifier circuit includes a startup control module, which is connected to the input terminal of the first integrator and is used to acquire the first signal and the input voltage signal, and output a first control signal, a second control signal and a common-mode signal based on the first signal and the input voltage signal. The first control signal and the second control signal are used to control the on / off state of the first switch, the second switch and the third switch, and the first integrator and the second integrator are used to acquire the common mode signal.

2. The power amplifier circuit according to claim 1, characterized in that, The first input terminal includes a first positive input terminal and a first negative input terminal, and the first output terminal includes a first positive output terminal and a first negative output terminal; The first integrator satisfies at least one of the following: A first resistor is provided on the first positive input terminal; A first resistor is provided on the first negative input terminal; A first capacitor is provided between the first positive input terminal and the first negative output terminal; A first capacitor is provided between the first negative input terminal and the first positive output terminal; And / or, the second input terminal includes a second positive input terminal and a second negative input terminal, and the second output terminal includes a second positive output terminal and a second negative output terminal; The second integrator satisfies at least one of the following: A second capacitor is provided between the second positive input terminal and the second negative output terminal; A second capacitor is provided between the second negative input terminal and the second positive output terminal.

3. The power amplifier circuit according to claim 1, characterized in that, At least one of the first switch, the second switch, and the third switch is a transmission gate.

4. The power amplifier circuit according to claim 1, characterized in that, The startup control module includes a common-mode voltage generation unit, which includes a first series resistor, a second series resistor, and a third series resistor connected in series. The first series resistor is also used to connect to the input voltage signal, and the third series resistor is also used to ground. A common-mode signal output terminal is provided between the first series resistor and the second series resistor, and the common-mode signal output terminal is used to output the common-mode signal. The startup control module further includes a comparator unit, which comprises a first reference current source, a first bias switch, a second bias switch, a third bias switch, a first differential switch, and a second differential switch. The first bias switch and the first reference current source are connected in series, and the first bias switch is also used to connect to the input voltage signal. The first reference current source is also used to ground. The first differential switch and the second differential switch are connected in parallel and then in series with the second bias switch. The first differential switch and the second differential switch are also used to ground. The second bias switch is also used to connect to the input voltage signal. The control electrode of the first differential switch is connected between the second series resistor and the third series resistor, and the control electrode of the second differential switch is used to connect to the first signal. One end of the third bias switch is used to connect to the input voltage signal, and the other end is grounded. The control electrodes of the first bias switch, the second bias switch, and the third bias switch are all connected to the end of the first bias switch connected to the first reference current source. The startup control module further includes a delay output unit, which includes a delay module and an inverter. One end of the delay module is connected to the grounded end of the third bias switch, and the other end of the delay module is connected to the inverter. The inverter is used to output the first control signal and the second control signal.

5. The power amplifier circuit according to claim 1, characterized in that, The power amplifier circuit further includes a modulation module and an output module. The modulation module is connected to the second integrator and is used to acquire a third signal, and to output a modulation signal after modulating the third signal. The output module is connected to the modulation module and is used to acquire the modulation signal and output a fourth signal according to the modulation signal. The modulation module includes a triangular wave generator, a comparator, and a de-glitch unit. The triangular wave generator is connected to the negative input of the comparator, the positive input of the comparator is used to receive the third signal, and the de-glitch unit is connected to the output of the comparator and to the output module. The power amplifier circuit also includes a noise suppression module, which is used to acquire a third signal and a first modulation signal. The first modulation signal is the lowest reference voltage signal of the triangular wave generator. The noise suppression module is used to output a suppression signal to the first input terminal based on the third signal and the first modulation signal.

6. The power amplifier circuit according to claim 5, characterized in that, The noise suppression module includes a second reference current source, a first current leakage switch, a second current leakage switch, a third current leakage switch, a fourth current leakage switch, and a fifth current leakage switch; the second reference current source and the first current leakage switch are connected in series, and the second reference current source is also used to receive an input voltage signal, while the first current leakage switch is also used to ground; the control terminals of the first current leakage switch, the second current leakage switch, the third current leakage switch, the fourth current leakage switch, and the fifth current leakage switch are all connected to the end of the first current leakage switch that is connected to the second reference current source; The noise suppression module further includes a first current source switch and a second current source switch. The first current source switch is connected in series with the second current drain switch. The first current source switch is also used to receive an input voltage signal, and the second current drain switch is also used to ground. The second current source switch is connected in series with the fourth current drain switch, and the second current source switch is also used to receive an input voltage signal. The fourth current drain switch is used to ground. The control terminals of the first current source switch and the second current source switch are connected to the same end of the first current source switch connected to the second current drain switch. The noise suppression module further includes a first current mirror unit and a second current mirror unit that are symmetrical to each other. The noise suppression module also includes a first signal input switch, a second signal input switch, and a third signal input switch. The first signal input switch is connected to the first current mirror unit, and the second current source switch, the first signal input switch, and the third current drain switch are connected in series. The third signal input switch is connected to the second current mirror unit, and the second current source switch, the third signal input switch, and the fifth current drain switch are connected in series. The second current source switch, the second signal input switch, and the fourth current drain switch are connected in series. The control electrode of the first signal input switch and the control electrode of the third signal input switch are used to connect to the third signal; the second signal input switch is used to connect to the first modulation signal.

7. An audio device, characterized in that, The audio device includes the power amplifier circuit as described in any one of claims 1 to 6.

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