Dynamic Modulation Method of Class D Amplifier and Its Electronic Circuit

Abstract

The present invention provides a dynamic modulation method for a class-D amplifier and its electronic circuit. In the dynamic modulation method of the class-D amplifier, by dynamically adjusting the average duty cycle of the audio amplification signal, the average duty cycle of the audio amplification signal is made to be a suitable duty cycle to reduce the circuit power consumption, that is, the average duty cycle of the audio amplification signal is maintained at a relatively low level when there is no audio input, thereby reducing the static power consumption, and when the power is medium or low, the loss caused by the inductor ripple current is also reduced.

Description

Technical Field

[0001] The present invention relates to the field of electronic circuits, and in particular to a dynamic modulation method for a class D amplifier and its electronic circuit. Background Art

[0002] The purpose of an audio power amplifier is to reproduce an input audio signal on a sound output element, providing the required volume and power level, and ensuring high power and low distortion in the reproduction.

[0003] Among them, among various types of audio power amplifiers, a class D amplifier is a high-efficiency audio amplifier that operates in a switching mode. It converts the input audio signal into a high-frequency pulse signal through pulse width modulation or pulse density modulation technology, amplifies it through a switching element, and finally restores it to an analog audio signal through a filter. The class D amplifier exhibits many advantages, especially higher efficiency.

[0004] However, in the PWM modulation technology of a class D amplifier, its output signal swings around the supply voltage of the power amplifier, resulting in a large inductor ripple current when there is no music playing in the class D amplifier, leading to a high static power consumption. And when the class D amplifier is at medium and low volumes, the swing amplitude of its output signal is limited, resulting in too much margin for the common-mode voltage to leave for the output signal swing, causing waste in power consumption.

[0005] To improve the above problems, please refer to Figure 1 . The prior art provides a modulation circuit for a class D amplifier. The modulation circuit includes a signal input terminal and a common-mode voltage dynamic adjustment module. Among them, the signal input terminal is used to convert the received analog audio signal into a differential audio signal Vin, and the common-mode voltage dynamic adjustment unit is used to dynamically adjust the common-mode voltage of the differential audio signal. However, since this circuit modulates the analog audio signal, its design is difficult and the circuit is relatively complex. Summary of the Invention

[0006] The technical solution of the present invention provides a dynamic modulation method for a class D amplifier and its electronic circuit to reduce the power consumption of the circuit through a simple circuit.

[0007] According to the technical solution of the present invention, a dynamic modulation method for a class D amplifier is provided, including:

[0008] Continuously collecting a first signal from the digital signal processing module;

[0009] Generating a current second signal according to the current first signal, and the amplitude of the current second signal is the same as the amplitude of the audio amplification signal;

[0010] Generate a current control signal according to the current second signal to control the average duty cycle of the audio amplification signal.

[0011] Optionally, the acquisition position of the first signal is any position in the digital signal processing module.

[0012] Optionally, generate a current second signal according to the current first signal, and the amplitude of the current second signal is the same as the amplitude of the audio amplification signal, including:

[0013] Obtain a configured gain A, where the configured gain A is used to represent the product of various gains that affect the amplitude of the audio amplification signal during the process from the first signal at the corresponding acquisition position to the output audio amplification signal, and each acquisition position has a corresponding configured gain A;

[0014] Generate a current second signal according to the current first signal and the configured gain A, and the amplitude F2 of the current second signal = A × F1, where F1 is used to represent the amplitude of the current first signal.

[0015] Optionally, the class D amplifier further includes an analog amplification module. The input end of the analog amplification module is coupled to the digital signal processing module through a digital-to-analog conversion unit. The output end of the analog amplification module is used to output an audio amplification signal, and the control signal controls the duty cycle of the audio amplification signal by controlling the common-mode level of the analog amplification module.

[0016] Optionally, generate a current control signal according to the current second signal to control the average duty cycle of the audio amplification signal, including:

[0017] Provide a plurality of judgment thresholds, and the plurality of judgment thresholds correspond to a plurality of duty cycles one by one;

[0018] Obtain a first judgment threshold: if the current second signal is the initial second signal, use one of the plurality of judgment thresholds as the first judgment threshold; if the current second signal is the changed second signal, use the second judgment threshold formed under the previous second signal as the first judgment threshold;

[0019] Compare the amplitude of the current second signal with the first judgment threshold to adjust or maintain the first judgment threshold, form a second judgment threshold under the current second signal, and generate a current control signal to control the average duty cycle of the audio amplification signal.

[0020] Optionally, generating a current control signal according to the current second signal to control the average duty cycle of the audio amplification signal further includes:

[0021] Provide a number of judgment levels corresponding one by one to a number of judgment thresholds;

[0022] Obtain the corresponding first judgment threshold according to the first judgment level: If the current second signal is the initial second signal, use the preset judgment level as the first judgment level, and the judgment threshold corresponding to the first judgment level as the first judgment threshold; If the current second signal is the changed second signal, use the second judgment level formed under the previous second signal as the first judgment level, and the judgment threshold corresponding to the second judgment level as the first judgment threshold.

[0023] Optionally, the number of judgment thresholds includes M judgment thresholds set in ascending order, the M judgment thresholds set in ascending order correspond to M duty cycles set in ascending order, and among any two adjacent judgment thresholds, the latter judgment threshold is greater than the former judgment threshold, M is a positive integer, and compare the amplitude of the current second signal with the first judgment threshold to adjust or maintain the first judgment threshold to form a second judgment threshold, and generate a current control signal to control the average duty cycle of the audio amplification signal, including:

[0024] Set the first value to 0 and the second value to 0. The first value is used to represent the continuous number of times that the amplitude of the second signal is greater than the first judgment threshold, and the second value is used to represent the continuous number of times that the amplitude of the second signal is less than the first judgment threshold;

[0025] Compare the amplitude of the current second signal with the first judgment threshold to update the first value and the second value: If the amplitude of the current second signal is greater than the first judgment threshold, the first value is incremented by 1 and the second value is cleared; If the amplitude of the current second signal is less than the first judgment threshold, the second value is incremented by 1 and the first value is cleared; If the amplitude of the current second signal is equal to the first judgment threshold, both the first value and the second value are cleared;

[0026] Based on the first value and the second value, a second judgment threshold is formed, and a current control signal is generated: If the first value is m, the first value is cleared, the next judgment threshold of the current first judgment threshold is used as the second judgment threshold, and a current control signal is generated to increase the average duty cycle of the audio amplification signal to the duty cycle corresponding to the second judgment threshold; if the second value is n, the second value is cleared, the previous judgment threshold of the current first judgment threshold is used as the second judgment threshold, and a current control signal is generated to reduce the average duty cycle of the audio amplification signal to the duty cycle corresponding to the second judgment threshold; if the first value is less than m and the second value is less than n, the current first judgment threshold is used as the second judgment threshold, and a current control signal is generated to keep the average duty cycle of the audio amplification signal the same as the duty cycle corresponding to the second judgment threshold. Both m and n are positive integers.

[0027] Optionally, before comparing the amplitude of the current second signal with the first judgment threshold, it further includes: smoothing N second signals within the first time period to output a second smoothed signal, and the amplitude Avg of the second smoothed signal = (T1 + T2 +... + TN) / N, where N is a positive integer, and TN is used to represent the amplitude of the Nth second signal within the first time period.

[0028] Optionally, before comparing the amplitude of the current second signal with the first judgment threshold, it further includes: smoothing the current second signal to output a second smoothed signal, and the amplitude Avg2 of the Nth output second smoothed signal = Avg1×alpha + TN×(1 - alpha), where N is a positive integer, TN is used to represent the amplitude of the Nth second signal, Avg1 is used to represent the amplitude of the (N - 1)th second smoothed signal, alpha is used to represent the smoothing weight of the smoothing process, and 0 < alpha < 1.

[0029] According to the technical solution of the present invention, an electronic circuit is further provided for implementing the dynamic modulation method of the D - class amplifier mentioned above.

[0030] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0031] In the dynamic modulation method of the D - class amplifier provided by the technical solution of the present invention, by dynamically adjusting the average duty cycle of the audio amplification signal, the average duty cycle of the audio amplification signal is made to be an appropriate duty cycle to reduce the circuit power consumption, that is, the average duty cycle of the audio amplification signal is maintained at a relatively low level when there is no audio input, thereby reducing the static power consumption, and at medium and low powers, the loss caused by the inductor ripple current will also be reduced.

[0032] Furthermore, after performing data smoothing processing on the second signal input to the dynamic adjustment module, it is possible to prevent the mutation of the average duty cycle of the subsequent audio amplification signal caused by the mutation of the second signal within a short period of time.

[0033] In the electronic circuit provided by the technical solution of the present invention, since the digital signal is collected from the digital signal processing module, the circuit for implementing the modulation method of the class D amplifier is a digital circuit, and the structure of this digital circuit is relatively simple compared with the analog circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a circuit block diagram of a modulation circuit of a class D amplifier;

[0035] Figure 2 is a flowchart of a dynamic modulation method of a class D amplifier provided by an embodiment of the present invention;

[0036] Figure 3 is a flowchart of a method for obtaining a current control signal according to a current second signal in a dynamic modulation method of a class D amplifier provided by an embodiment of the present invention Figure 1 ;

[0037] Figure 4 is a flowchart of a method for obtaining a current control signal according to a current second signal in a dynamic modulation method of a class D amplifier provided by an embodiment of the present invention Figure 2 ;

[0038] Figure 5 is a flowchart of a method for obtaining a corresponding first judgment threshold according to a first judgment level in a dynamic modulation method of a class D amplifier provided by another embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] As described in the background art, the class D amplifier will cause a large amount of power consumption waste both when there is no music playing and when playing at medium and low volumes. The solution to this problem in the prior art is to change the common-mode voltage of the analog audio signal. However, since the common-mode voltage dynamic adjustment module processes analog signals, its design difficulty is relatively large and the circuit is relatively complex.

[0040] In view of this, the technical solution of the present invention creatively proposes a dynamic modulation method for a class D amplifier, including:

[0041] Continuously collect a first signal from the digital signal processing module; generate a current second signal according to the current first signal, wherein the amplitude of the current second signal is the same as that of the audio amplification signal; generate a current control signal according to the current second signal to control the average duty cycle of the audio amplification signal.

[0042] By dynamically adjusting the average duty cycle of the audio amplification signal, the average duty cycle of the audio amplification signal is made to be a suitable duty cycle to reduce the circuit power consumption, that is, the average duty cycle of the audio amplification signal is maintained at a relatively low level when there is no audio input, thereby reducing the static power consumption, and when the power is medium or low, the loss caused by the inductor ripple current is also reduced.

[0043] The following will clearly and completely describe the embodiments in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention. The terms "first", "second", "third", etc. in the specification and claims of the present invention and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order different from those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0044] Figure 2 is a flowchart of a dynamic modulation method of a class D amplifier provided by an embodiment of the present invention, Figure 3 is a flowchart of a method for obtaining a current control signal according to a current second signal in a dynamic modulation method of a class D amplifier provided by an embodiment of the present invention Figure 1 , Figure 4 is a flowchart of a method for obtaining a current control signal according to a current second signal in a dynamic modulation method of a class D amplifier provided by an embodiment of the present invention Figure 2 .

[0045] In this embodiment, the class-D amplifier includes a digital signal processing module, a digital-to-analog conversion unit, and an analog amplification module. The class-D amplifier analogizes and amplifies the digital audio signal obtained from the digital signal processing module to output an audio amplified signal. Among them, the digital signal processing module is used to perform digital processing on the input digital audio signal, and its output terminal is connected to the input terminal of the digital-to-analog conversion unit. The output terminal of the digital-to-analog conversion unit is connected to the input terminal of the analog amplification module, and the output terminal of the analog amplification module is used to output an audio amplified signal.

[0046] Please refer to Figure 2 , the dynamic modulation method of the class-D amplifier includes:

[0047] Continuously collect a first signal from the digital signal processing module.

[0048] Specifically, the first signal is a signal that is time-discrete but amplitude-continuous and is collected at a fixed frequency in the digital signal processing module.

[0049] In this embodiment, the acquisition position of the first signal is any position in the digital signal processing module. Specifically, the digital signal processing module includes a sample rate conversion unit, a Σ-Δ modulator, etc. Any position can be understood as any position in the digital signal processing module where a digital signal is generated.

[0050] Generate a current second signal according to the current first signal, and the amplitude of the current second signal is the same as the amplitude of the audio amplified signal.

[0051] In this embodiment, generating a current second signal according to the current first signal may include:

[0052] Obtain a configured gain A, where the configured gain A is used to represent the product of various gains that affect the amplitude of the audio amplified signal during the process from the first signal at the corresponding acquisition position to the output of the audio amplified signal. Each acquisition position has a corresponding configured gain A.

[0053] Generate a current second signal according to the current first signal and the configured gain A. The amplitude F2 of the current second signal = A × F1, where F1 is used to represent the amplitude of the current first signal. Among them, the amplitude F2 of the second signal will change correspondingly with the amplitude F1 of the corresponding first signal, and the second signal is also a time-discrete but amplitude-continuous signal.

[0054] In one embodiment, if the first signal acquisition position is close to the input end of the digital signal processing module, that is, if there is a gain that affects the amplitude of the output signal of the digital signal processing module during the process from the acquisition position of the first signal to the output end of the digital signal processing module, the configured gain is configured as the product of the digital gain and the analog gain. The digital gain can be understood as the gain that affects the amplitude of the output signal of the digital signal processing module during the process from the acquisition position of the first signal to the output end of the digital signal processing module, and the analog gain can be understood as the gain in the analog amplification module that can affect the amplitude of the audio amplification signal.

[0055] In another embodiment, if the first signal acquisition position is close to the output end of the digital signal processing module, that is, if there is no gain that affects the amplitude of the output signal of the digital signal processing module during the process from the acquisition position of the first signal to the output end of the digital signal processing module, the configured gain includes the analog gain, and the analog gain can be understood as the gain in the analog amplification module that can affect the amplitude of the audio amplification signal.

[0056] Wherein, the amplitude F2 of each second signal is the same as the amplitude of the corresponding audio amplification signal. The amplitude of the corresponding audio amplification signal can be understood as the amplitude of the corresponding first signal passing through the digital signal processing module part, digital-to-analog conversion unit, and analog amplification module after the acquisition position until the amplitude of the corresponding audio amplification signal is output.

[0057] It should be noted that since the magnitude of the configured gain is not exactly the same as the gain of the signal during the process from the first signal to the audio amplification signal in the actual circuit, there will be a deviation between the amplitude of the audio amplification signal and the amplitude F2 of the second signal. However, this deviation is an acceptable deviation for this technical solution and will not affect the beneficial effects of this technical solution. Therefore, to a certain extent, it can be considered that the amplitude of the audio amplification signal is the same as the amplitude F2 of the second signal.

[0058] In one embodiment, after generating the current second signal according to the current first signal, the dynamic modulation method of the class D amplifier further includes smoothing N second signals within the first time period and outputting a second smoothed signal. The amplitude Avg of the second smoothed signal = (T1 + T2 +... + TN) / N, where N is a positive integer, and TN is used to represent the amplitude of the Nth second signal within the first time period.

[0059] In another embodiment, after generating the current second signal according to the current first signal, the dynamic modulation method of the class D amplifier further includes smoothing the current second signal to output a second smoothed signal, and the amplitude of the Nth output second smoothed signal Avg2 = Avg1×alpha + TN×(1 - alpha), where N is a positive integer, TN is used to represent the amplitude of the Nth second signal, Avg1 is used to represent the amplitude of the (N - 1)th second smoothed signal, alpha is used to represent the smoothing weight of the smoothing process, and 0 < alpha < 1. Those skilled in the art can set different values of alpha according to actual needs. For example, alpha can be 0.9.

[0060] Among them, smoothing the current second signal can prevent the mutation of the average duty cycle of the subsequent audio amplification signal caused by the mutation of the second signal in a short time.

[0061] Generate a current control signal C{...} according to the current second signal to control the average duty cycle of the audio amplification signal.

[0062] In this embodiment, the control signal C{...} controls the average duty cycle of the audio amplification signal by controlling the common-mode level of the analog amplification module. Of course, those skilled in the art can realize that there are many ways to change the average duty cycle of the audio amplification signal, and they are all within the protection scope of the present invention.

[0063] In one embodiment, please refer to Figure 3 , generating a current control signal C{...} according to the current second signal to control the average duty cycle of the audio amplification signal may include:

[0064] Provide a plurality of judgment thresholds D{...}, and the plurality of judgment thresholds D{...} correspond to a plurality of duty cycles one by one.

[0065] In this embodiment, the plurality of judgment thresholds D{...} include N judgment thresholds D{...} arranged in ascending order, the N judgment thresholds D{...} arranged in ascending order correspond to N duty cycles arranged in ascending order, and in any two adjacent judgment thresholds D{...}, the latter judgment threshold D{...} is greater than the former judgment threshold D{...}, and N is a positive integer. Among them, the difference between the duty cycles corresponding to any two adjacent judgment thresholds D{...} can be the same or different, and the largest duty cycle is less than or equal to 50%.

[0066] Obtain the first judgment threshold M1: If the current second signal is the initial second signal, use one of the several judgment thresholds D{...} as the first judgment threshold M1; if the current second signal is the changed second signal, use the second judgment threshold M2 formed under the previous second signal as the first judgment threshold M1.

[0067] Compare the amplitude F2 of the current second signal with the first judgment threshold M1 to adjust or maintain the first judgment threshold M1, form the second judgment threshold M2 under the current second signal, and generate the current control signal C{...} to control the average duty cycle of the audio amplification signal.

[0068] Among them, please refer to Figure 4 , comparing the amplitude F2 of the current second signal with the first judgment threshold M1 to adjust or maintain the first judgment threshold M1, form the second judgment threshold M2 under the current second signal, and generate the current control signal C{...} to control the average duty cycle of the audio amplification signal, may include:

[0069] Set the first value V1 to 0 and the second value V2 to 0. The first value V1 is used to represent the consecutive number of times that the amplitude F2 of the second signal is greater than the first judgment threshold M1, and the second value V2 is used to represent the consecutive number of times that the amplitude F2 of the second signal is less than the first judgment threshold M1.

[0070] Compare the amplitude F2 of the current second signal with the first judgment threshold M1 to update the first value V1 and the second value V2: If the amplitude F2 of the current second signal is greater than the first judgment threshold M1, increment V1 by 1 and clear V2 to 0; if the amplitude F2 of the current second signal is less than the first judgment threshold M1, increment V2 by 1 and clear V1 to 0; if the amplitude F2 of the current second signal is equal to the first judgment threshold M1, clear both V1 and V2 to 0.

[0071] Based on the first value V1 and the second value V2, a second judgment threshold M2 is formed, and a current control signal C{...} is generated: If the first value V1 is m, the first value V1 is cleared, the subsequent judgment threshold of the current first judgment threshold M1 is used as the second judgment threshold M2, and a current control signal C{...} is generated to increase the average duty cycle of the audio amplification signal to the duty cycle corresponding to the second judgment threshold M2; if the second value V2 is n, the second value V2 is cleared, the previous judgment threshold of the current first judgment threshold M1 is used as the second judgment threshold M2, and a current control signal C{...} is generated to reduce the average duty cycle of the audio amplification signal to the duty cycle corresponding to the second judgment threshold M2; if the first value V1 is less than m and the second value V2 is less than n, the current first judgment threshold M1 is used as the second judgment threshold M2, and a current control signal C{...} is generated to keep the average duty cycle of the audio amplification signal the same as the duty cycle corresponding to the second judgment threshold M2. Both m and n are positive integers. Among them, m and n can be the same or different, and m and n can be set according to the actual situation.

[0072] Specifically, please refer to Figure 4, initially, before the first second signal is input, the first value is set to 0, the second value is set to 0, and the first judgment threshold M1 is the x-th judgment threshold D{x}, that is, M1 = D{x}. If the amplitude F2 of the current second signal is greater than the first judgment threshold M1, the first value V1 is incremented by 1 and the second value V2 is cleared; if the amplitude F2 of the current second signal is less than the first judgment threshold M1, the second value V2 is incremented by 1 and the first value V1 is cleared; if the amplitude F2 of the current second signal is equal to the first judgment threshold M1, both the first value V1 and the second value V2 are cleared. Therefore, when the amplitudes F2 of m consecutive second signals are all greater than the first judgment threshold D{x}, the first value V1 = m and the second value V2 = 0. At this time, the formed second judgment threshold M2 is the next judgment threshold of the current first judgment threshold M1 = D{x}, that is, M2 = D{x + 1}, and a corresponding control signal C{x + 1} is generated to control the average duty cycle of the audio amplification signal to the duty cycle corresponding to the second judgment threshold M2 = D{x + 1}; when the amplitudes F2 of n consecutive second signals are all less than the first judgment threshold D{x}, the second value V2 = n and the first value V1 = 0. At this time, the formed second judgment threshold is the previous judgment threshold of the current first judgment threshold M1 = D{x}, that is, M2 = D{x - 1}, and a corresponding control signal C{x - 1} is generated to control the average duty cycle of the audio amplification signal to the duty cycle corresponding to the second judgment threshold M2 = D{x - 1}; when the first value V1 is less than m and the second value V2 is less than n, the current first judgment threshold M1 = D{x} is used as the second judgment threshold, that is, M2 = D{x}, and the current control signal C{x} is generated to keep the average duty cycle of the audio amplification signal the same as the duty cycle corresponding to the second judgment threshold M2 = D{x}. Therefore, the average duty cycle of the audio amplification signal is adjusted step by step, which can reduce the change of the duty cycle each time, thereby weakening the sound quality loss caused by the duty cycle. If m is greater than 1, only when the amplitudes F2 of m consecutive second signals are judged to be greater than the first judgment threshold M1, the average duty cycle of the audio amplification signal will be increased. If n is greater than 1, only when the amplitudes F2 of n consecutive second signals are judged to be less than the first judgment threshold M1, the average duty cycle of the audio amplification signal will be decreased, thus avoiding the sudden change and frequent change of the average duty cycle of the audio amplification signal caused by the sudden change of the second signal, and further increasing the stability of the average duty cycle of the audio amplification signal.

[0073] In one embodiment, the control signal C{...} includes M different control signals C{...}, and the M control signals C{...} correspond one-to-one with M different duty cycles to control the average duty cycle of the audio amplification signal to be the corresponding duty cycle.

[0074] In another embodiment, the control signal C{...} includes three control signals to increase, decrease or maintain the average duty cycle of the audio amplification signal. At this time, the analog amplification module further includes a signal analysis unit for converting the received control signal into a control signal corresponding one-to-one with a specific duty cycle to control the average duty cycle of the audio amplification signal to be the corresponding duty cycle.

[0075] In another embodiment, generating a current control signal C{...} according to the current second signal to control the average duty cycle of the audio amplification signal may include:

[0076] Providing a plurality of judgment thresholds D{...}, and the plurality of judgment thresholds D{...} correspond one-to-one with a plurality of duty cycles.

[0077] Providing a plurality of judgment levels corresponding one-to-one with the plurality of judgment thresholds D{...}.

[0078] Obtaining a corresponding first judgment threshold M1 according to the first judgment level: If the current second signal is the initial second signal, using the preset judgment level as the first judgment level and the judgment threshold D{...} corresponding to the first judgment level as the first judgment threshold M1; if the current second signal is the changed second signal, using the second judgment level formed under the previous second signal as the first judgment level and the judgment threshold D{...} corresponding to the second judgment level as the first judgment threshold M1.

[0079] In this embodiment, please refer to Figure 5 , Figure 5 FIG. is a flowchart of a method for obtaining a corresponding first judgment threshold according to the first judgment level in a dynamic modulation method of a class D amplifier provided by another embodiment of the present invention. The method of obtaining a corresponding first judgment threshold M1 according to the first judgment level by using a step-by-step judgment method is adopted. For example, starting from the Mth judgment level, if it is judged that the first judgment level is the Mth level, then the first judgment threshold M1 is equal to the Mth judgment threshold corresponding to the Mth judgment level. If it is judged that the first judgment level is not equal to the Mth level, then it will continue to judge whether the first judgment level is the (M - 1)th judgment level.

[0080] Compare the amplitude F2 of the current second signal with the first judgment threshold M1 to adjust or maintain the first judgment level, form a second judgment level under the current second signal, and generate a current control signal C{...} to control the average duty cycle of the audio amplification signal.

[0081] Among them, comparing the amplitude F2 of the current second signal with the first judgment threshold M1 to adjust or maintain the first judgment level, form a second judgment level under the current second signal, and generate a current control signal C{...} to control the average duty cycle of the audio amplification signal may include:

[0082] Set a first value V1 to 0 and a second value V2 to 0. The first value V1 is used to represent the consecutive number of times that the amplitude F2 of the second signal is greater than the first judgment threshold M1, and the second value V2 is used to represent the consecutive number of times that the amplitude F2 of the second signal is less than the first judgment threshold M1.

[0083] Compare the amplitude F2 of the current second signal with the first judgment threshold M1 to update the first value V1 and the second value V2: If the amplitude F2 of the current second signal is greater than the first judgment threshold M1, the first value V1 is incremented by 1 and the second value V2 is cleared; if the amplitude F2 of the current second signal is less than the first judgment threshold M1, the second value V2 is incremented by 1 and the first value V1 is cleared; if the amplitude F2 of the current second signal is equal to the first judgment threshold M1, both the first value V1 and the second value V2 are cleared.

[0084] Based on the first value V1 and the second value V2, the second judgment level is formed, and the current control signal C{...} is generated: If the first value V1 is m, the first value V1 is cleared, the next judgment level of the current first judgment level is used as the second judgment level, and the current control signal C{...} is generated to increase the average duty cycle of the audio amplification signal to the duty cycle corresponding to the second judgment threshold M2; if the second value V2 is n, the second value V2 is cleared, the previous judgment level of the current first judgment level is used as the second judgment level, and the current control signal C{...} is generated to reduce the average duty cycle of the audio amplification signal to the duty cycle corresponding to the second judgment threshold M2; if the first value V1 is less than m and the second value V2 is less than n, the current first judgment level is used as the second judgment level, and the current control signal C{...} is generated to keep the average duty cycle of the audio amplification signal the same as the duty cycle corresponding to the second judgment threshold M2. Both m and n are positive integers. Here, m and n can be the same or different, and m and n can be set according to the actual situation.

[0085] In summary, by dynamically adjusting the average duty cycle of the audio amplification signal, the average duty cycle of the audio amplification signal is made to be an appropriate duty cycle to reduce the circuit power consumption, that is, the average duty cycle of the audio amplification signal is kept at a low level when there is no audio input, thereby reducing the static power consumption, and when the power is medium and low, the loss caused by the inductor ripple current will also be reduced.

[0086] An embodiment of the present invention further provides an electronic circuit for implementing the dynamic modulation method of the class D amplifier in the above embodiment.

[0087] Among them, since the digital signal is collected from the digital signal processing module, the circuit for implementing the modulation method of the class D amplifier in the above embodiment is a digital circuit, and compared with the analog circuit, the structure of this digital circuit is relatively simple.

[0088] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A dynamic modulation method for a class D amplifier, wherein the class D amplifier comprises a digital signal processing module, and the class D amplifier simulates and amplifies a digital audio signal obtained in the digital signal processing module to output an audio amplified signal, characterized in that: include: Continuously collecting a first signal from the digital signal processing module, where a collection position of the first signal is any position in the digital signal processing module; Generate a current second signal according to the current first signal, wherein the amplitude of the current second signal is the same as the amplitude of the audio amplified signal, including: obtaining a configuration gain A, wherein the configuration gain A is used to characterize the product of various gains that affect the amplitude of the audio amplified signal in the process from the first signal of the corresponding acquisition position to the output of the audio amplified signal, and each acquisition position has a corresponding configuration gain A; generate a current second signal according to the current first signal and the configuration gain A, wherein the amplitude of the current second signal F2=A×F1, and F1 is used to characterize the amplitude of the current first signal; Generate a current control signal according to the current second signal to control the average duty cycle of the audio amplified signal, including: providing a plurality of judgment thresholds, wherein the plurality of judgment thresholds correspond to a plurality of duty cycles one by one; obtain a first judgment threshold: if the current second signal is an initial second signal, use one of the plurality of judgment thresholds as the first judgment threshold; if the current second signal is a changed second signal, use the second judgment threshold formed under the previous second signal as the first judgment threshold; compare the amplitude of the current second signal with the first judgment threshold to adjust or maintain the first judgment threshold, form the second judgment threshold under the current second signal, and generate the current control signal to control the average duty cycle of the audio amplified signal.

2. The dynamic modulation method of a class D amplifier according to claim 1, characterized in that: The Class D amplifier also includes an analog amplification module, an input end of the analog amplification module is coupled to the digital signal processing module through a digital-to-analog conversion unit, an output end of the analog amplification module is used to output an audio amplification signal, and the control signal controls the duty cycle of the audio amplification signal by controlling the common mode level of the analog amplification module.

3. The dynamic modulation method of a class D amplifier according to claim 1, characterized in that: Generating a current control signal according to the current second signal to control the average duty cycle of the audio amplified signal also includes: Providing a number of judgment levels corresponding to a number of judgment thresholds; Obtain the corresponding first judgment threshold according to the first judgment level: if the current second signal is the initial second signal, use the preset judgment level as the first judgment level, and the judgment threshold corresponding to the first judgment level as the first judgment threshold; if the current second signal is the changed second signal, use the second judgment level formed under the previous second signal as the first judgment level, and the judgment threshold corresponding to the second judgment level as the first judgment threshold.

4. The dynamic modulation method of a class D amplifier according to claim 1, characterized in that: The plurality of judgment thresholds include M judgment thresholds arranged in ascending order, the M judgment thresholds arranged in ascending order correspond to M duty cycles arranged in ascending order, and in any two adjacent judgment thresholds, the latter judgment threshold is greater than the former judgment threshold, M is a positive integer, and the amplitude of the current second signal is compared with the first judgment threshold to adjust or maintain the first judgment threshold to form a second judgment threshold, and a current control signal is generated to control the average duty cycle of the audio amplified signal, including: Set a first value to 0 and a second value to 0, wherein the first value is used to represent the number of consecutive times that the amplitude of the second signal is greater than the first judgment threshold, and the second value is used to represent the number of consecutive times that the amplitude of the second signal is less than the first judgment threshold; Compare the amplitude of the current second signal with the first judgment threshold to update the first value and the second value: if the amplitude of the current second signal is greater than the first judgment threshold, the first value is increased by 1, and the second value is cleared; if the amplitude of the current second signal is less than the first judgment threshold, the second value is increased by 1, and the first value is cleared; if the amplitude of the current second signal is equal to the first judgment threshold, the first value and the second value are both cleared; According to the first value and the second value, the second judgment threshold is formed, and a current control signal is generated: if the first value is m, the first value is cleared, a judgment threshold after the current first judgment threshold is used as the second judgment threshold, and a current control signal is generated to increase the average duty cycle of the audio amplified signal to the duty cycle corresponding to the second judgment threshold; if the second value is n, the second value is cleared, a judgment threshold before the current first judgment threshold is used as the second judgment threshold, and a current control signal is generated to reduce the average duty cycle of the audio amplified signal to the duty cycle corresponding to the second judgment threshold; if the first value is less than m and the second value is less than n, the current first judgment threshold is used as the second judgment threshold, and a current control signal is generated to keep the average duty cycle of the audio amplified signal the same as the duty cycle corresponding to the second judgment threshold, and m and n are both positive integers.

5. The dynamic modulation method of a class D amplifier according to claim 1, characterized in that: Before comparing the amplitude of the current second signal with the first judgment threshold, the method also includes: smoothing the N second signals within the first time, outputting a second smoothed signal, the amplitude of the second smoothed signal Avg = (T1 + T2 + ... + TN) / N, N is a positive integer, and TN is used to characterize the amplitude of the Nth second signal within the first time.

6. The dynamic modulation method of a class D amplifier according to claim 1, characterized in that: Before comparing the amplitude of the current second signal with the first judgment threshold, the method also includes: smoothing the current second signal, outputting a second smoothed signal, and the amplitude of the output Nth second smoothed signal Avg2= Avg1×alpha+ TN×(1-alpha), where N is a positive integer, TN is used to characterize the amplitude of the Nth second signal, Avg1 is used to characterize the amplitude of the (N-1)th second smoothed signal, alpha is used to characterize the smoothing weight of the smoothing process, and 0<alpha<1.

7. An electronic circuit, characterized in that: A dynamic modulation method for implementing a class D amplifier as claimed in any one of claims 1 to 6.

Images