A low-latency noise reduction circuit, method and active noise reduction earphone

Abstract

The present invention provides a low-latency noise reduction circuit, method and active noise reduction headphones, the circuit includes: an MCU connected to a sound receiving device, performing inversion processing on the received environmental noise, transmitting the obtained inversion noise to a PDM interface module for processing, transmitting the obtained PDM code stream data signal to a CIC filter to restore it to the first PCM data, performing noise shaping and quantization processing on the first PCM data by a noise shaping module, performing pulse width modulation on the obtained second PCM data in a PWM module, and transmitting the obtained pulse data to a power amplifier device for playback. In this solution, the environmental noise is processed by an external MCU for sound effects, and the PDM channel processes it again and then plays it quickly, completing the cancellation with the environmental noise, thereby achieving the purpose of low-latency noise reduction.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, and in particular to a low-latency noise reduction circuit, method and active noise reduction headphones. Background Art

[0002] Current active noise reduction headphones all contain a microphone. The active noise reduction headphones use the microphone to receive ambient noise, process the ambient noise through an audio coding chip (codec), and obtain a noise signal that is inverted from the ambient noise. The noise reduction process is: while the active noise reduction headphones are playing music, the inverted noise signal is broadcast, thereby canceling out the ambient noise.

[0003] In the prior art, codec chips are mainly used for noise reduction. However, in addition to the built-in sound effect processing module, the codec chip also has other modules that are not related to the noise reduction application. Not only is the codec chip large in area and high in cost, but also because there are modules unrelated to noise processing in the codec chip, the built-in sound effect processing module processes the ambient noise, which will increase a certain delay. Summary of the invention

[0004] In view of this, embodiments of the present invention provide a low-latency noise reduction circuit, method and active noise reduction headphones to achieve the purpose of low-cost and low-latency noise reduction.

[0005] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0006] A low-latency noise reduction circuit disclosed in a first aspect of an embodiment of the present invention includes: a microprocessor MCU and a noise reduction path;

[0007] The input end of the MCU is connected to the sound receiving device, and the output end is connected to the noise reduction path. The MCU performs inversion processing on the environmental noise received by the sound receiving device and transmits the obtained inverted noise to the noise reduction path;

[0008] The noise reduction path includes: a pulse density modulation PDM interface module, an integral comb CIC filter, a noise shaping module and a pulse width modulation PWM module;

[0009] The input end of the PDM interface module is connected to the output end of the MCU, and the output end is connected to the CIC filter. The PDM interface module processes the anti-phase noise to obtain a PDM code stream data signal;

[0010] The output end of the CIC filter is connected to the input end of the noise shaping module, and the CIC filter restores the PDM code stream data signal into a first pulse code modulation PCM data signal;

[0011] The output end of the noise shaping module is connected to the input end of the PWM module, and the noise shaping module performs noise shaping and quantization processing on the first PCM data signal to obtain a second PCM data signal;

[0012] The output end of the PWM module is connected to the power amplifier device. The PWM module performs pulse width modulation on the second PCM data signal and transmits the obtained pulse data signal to the power amplifier device.

[0013] Optionally, the PDM interface module includes a clock interface PDM_CLK and a data interface PDM_DATA;

[0014] The PDM code stream data includes a left channel data signal and a right channel data signal, and the left channel data signal and the right channel data signal are composed of a 1-bit data stream;

[0015] The left channel data signal is obtained by sampling the anti-phase noise at the rising edge of the clock interface PDM_CLK;

[0016] The right channel data signal is obtained by sampling the anti-phase noise at the falling edge of the data interface PDM_CLK;

[0017] The left channel data signal and the right channel data signal are multiplexed through the data interface PDM_DATA to obtain the PDM code stream data signal.

[0018] Optionally, the integral comb CIC filter includes: a 3rd order CIC filter and / or a 4th order CIC filter.

[0019] Optionally, the noise shaping module includes a Delta-Sigma module.

[0020] A low-latency noise reduction method disclosed in a second aspect of an embodiment of the present invention is applied to the low-latency noise reduction circuit disclosed in the first aspect of an embodiment of the present invention. The low-latency noise reduction method includes:

[0021] The microprocessor MCU obtains the environmental noise received by the sound receiving device, performs inversion processing on the environmental noise, and transmits the obtained inverted noise to the pulse density modulation PDM interface module;

[0022] The PDM interface module samples and multiplexes the anti-phase noise, and transmits the obtained PDM code stream data signal to the integral comb CIC filter;

[0023] The CIC filter restores the PDM code stream data signal and transmits the obtained first pulse code modulation PCM data signal to the noise shaping module;

[0024] The noise shaping module performs noise shaping and quantization processing on the first PCM data signal, and transmits the obtained second PCM data signal to the pulse width modulation (PWM) module;

[0025] The PWM module performs pulse width modulation on the second PCM data signal, and transmits the obtained pulse data signal to the power amplifier device, which is then output by the power amplifier device.

[0026] Optionally, the PDM interface module samples and multiplexes the anti-phase noise, and transmits the obtained PDM code stream data signal to the integral comb CIC filter, including:

[0027] The PDM interface module samples and multiplexes the anti-phase noise, and transmits the obtained 1-bit PDM code stream data signal of 64fs to the integral comb CIC filter, wherein fs is the sampling rate of the PDM interface module.

[0028] Optionally, the PDM interface module samples and multiplexes the anti-phase noise, including:

[0029] The anti-phase noise is sampled based on the rising edge of the clock interface PDM_CLK of the PDM interface module to obtain a left channel data signal;

[0030] The anti-phase noise is sampled based on the falling edge of the clock interface PDM_CLK of the PDM interface module to obtain a right channel data signal;

[0031] During the sampling process, the data interface PDM_DATA of the PDM interface module is used to multiplex the sampled left channel data signal and the right channel data signal, and at the end of the sampling, a PDM code stream data signal is obtained.

[0032] Optionally, the CIC filter restores the PDM code stream data signal and transmits the obtained first pulse code modulation PCM data signal to the noise shaping module, including:

[0033] The CIC filter restores the 1-bit PDM code stream data signal of 64fs, and transmits the obtained 10-bit pulse code modulation PCM data signal of 16fs to the noise shaping module.

[0034] Optionally, the PWM module performs pulse width modulation on the second PCM data signal, and transmits the obtained pulse data signal to a power amplifier device, which is output by the power amplifier device, including:

[0035] The PWM module receives the second PCM data signal and performs pulse width modulation on the second PCM data signal based on a reference signal, wherein the reference signal is a triangular modulation signal;

[0036] Wherein, when the second PCM data signal is greater than the triangle modulation signal, the PWM module outputs a high level;

[0037] When the second PCM data signal is smaller than the triangle modulation signal, the PWM module outputs a low level;

[0038] After the pulse width modulation is completed, the PWM module sends the obtained pulse data signal to the power amplifier device, which is then output by the power amplifier device.

[0039] The third aspect of the embodiment of the present invention discloses an active noise reduction headset, comprising: a sound receiving device, a microprocessor MCU, the low-latency noise reduction circuit and a power amplifier device disclosed in the first aspect of the embodiment of the present invention;

[0040] The low-latency noise reduction circuit is used to execute the low-latency noise reduction method disclosed in the second aspect of an embodiment of the present invention.

[0041] Based on the above-mentioned embodiments of the present invention, a low-latency noise reduction circuit, method and active noise reduction headphones are provided. The low-latency noise reduction circuit includes: an MCU (Microcontroller Unit) and a noise reduction path; the input end of the MCU is connected to a sound receiving device, and the output end is connected to the noise reduction path. The MCU performs inversion processing on the ambient noise received by the sound receiving device, and transmits the obtained inverted noise to the noise reduction path; the noise reduction path includes: a PDM (Pulse Density Modulation) interface module, a CIC (Cascade Integrator Comb) filter, a noise shaping module and a PWM (Pulse width modulation) module. The input end of the PDM interface module is connected to the output end of the MCU, and the output end is connected to the CIC filter. The PDM interface module processes the antiphase noise to obtain a PDM code stream data signal; the output end of the CIC filter is connected to the input end of the noise shaping module, and the CIC filter restores the PDM code stream data signal to a first PCM (Pulse Code Modulation) data signal; the output end of the noise shaping module is connected to the input end of the PWM module, and the noise shaping module performs noise shaping and quantization processing on the first PCM data signal to obtain a second PCM data signal; the output end of the PWM module is connected to the power amplifier device, and the PWM module performs pulse width modulation on the second PCM data signal, and transmits the obtained pulse data signal to the power amplifier device. In the embodiment of the present invention, the ambient noise is processed by sound effects in an external MCU, and after a series of processing by a PDM interface module, a CIC filter, a noise shaping module and a PWM module, the obtained pulse data signal is quickly sent out to cancel the ambient noise. This process does not rely on the audio codec chip to process the ambient noise, but provides a low-latency path related to noise reduction, which not only saves the audio codec chip and many irrelevant circuits it brings, saves costs, but also achieves the purpose of low-latency noise reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0043] Figure 1 A schematic diagram of the structure of a low-latency noise reduction circuit disclosed in an embodiment of the present invention;

[0044] Figure 2A schematic diagram of the structure of a noise reduction path disclosed in an embodiment of the present invention;

[0045] Figure 3 A waveform diagram of sampling and multiplexing of a PDM interface module disclosed in an embodiment of the present invention;

[0046] Figure 4 A multiplexing structure of a 3rd-order CIC filter and a 4th-order CIC filter disclosed in an embodiment of the present invention;

[0047] Figure 5 It is a comparative schematic diagram when the reference signal of the PWM disclosed in the embodiment of the present invention is a triangular modulation signal;

[0048] Figure 6 A schematic diagram of a process flow of a low-latency noise reduction method disclosed in an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] In this application, the terms "comprises", "comprising" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0051] The following are the terms used in the embodiments of the present invention:

[0052] PDM, or pulse density modulation, is a modulation method that uses digital signals to represent analog signals. In a PDM signal, the relative density of the pulses corresponds to the amplitude of the analog signal.

[0053] PCM, or pulse code modulation, is a modulation method that uses binary coded numbers to represent the amplitude of an analog signal.

[0054] PWM, or pulse width modulation, digitally encodes the analog signal level and modulates the signal by adjusting the duty cycle.

[0055] CIC, or integral comb filter, is a cascade of an integrator and a comb filter. Depending on its structure, it can realize the decimation function and the interpolation function respectively.

[0056] Delta-Sigma Modulation, through integral quantization and feedback, trades speed for accuracy and moves quantization noise from low frequency to high frequency.

[0057] As can be seen from the background technology, the prior art uses codec chips for noise reduction. Codec chips are not only large in area and high in cost, but also contain modules that are not related to noise processing. When the built-in sound processing module processes the ambient noise, a certain delay will be added. Therefore, the embodiment of the present invention discloses a low-latency noise reduction circuit, method and active noise reduction headphones, which provide a low-latency path related to noise reduction, which can not only save audio codec chips and many irrelevant circuits brought by them, save costs, but also achieve the purpose of low-latency noise reduction. It is described in detail through the following embodiments.

[0058] like Figure 1 , which is a schematic diagram of the structure of a low-latency noise reduction circuit disclosed in an embodiment of the present invention. The low-latency noise reduction circuit mainly includes: a microprocessor MCU and a noise reduction path 10.

[0059] The input end of the MCU is connected to the sound receiving device 11 , and the output end is connected to the noise reduction path 10 .

[0060] The MCU performs inversion processing on the environmental noise received by the sound receiving device 11 , and transmits the obtained inverted noise to the noise reduction path 10 .

[0061] The noise reduction path 10 performs pulse density modulation on the received anti-phase noise, and then uses filtering, integral quantization and feedback, and finally digitally encodes the environmental noise after the above series of processing through pulse width modulation, and sends the obtained data signal to the analog Class D amplifier for playback.

[0062] When processing environmental noise, the embodiment of the present invention does not rely on the audio codec chip to process the environmental noise, but provides a low-latency path related to noise reduction, which not only saves the audio codec chip and many irrelevant circuits it brings, saves costs, but also achieves the purpose of low-latency noise reduction.

[0063] like Figure 2 As shown, the noise reduction path 10 specifically includes: a PDM interface module 21 , a CIC filter 22 , a noise shaping module 23 and a PWM module 24 .

[0064] The input end of the PDM interface module 21 is connected to the output end of the MCU, and the output end of the PDM interface module 21 is connected to the CIC filter 33 .

[0065] The PDM interface module 21 processes the anti-phase noise transmitted from the MCU to obtain a PDM code stream data signal.

[0066] In a specific implementation, the PDM interface module 21 includes a clock interface PDM_CLK and a data interface PDM_DATA.

[0067] The PDM code stream data includes a left channel data signal and a right channel data signal, and the left channel data signal and the right channel data signal are composed of 1-bit data streams.

[0068] The left channel data signal is obtained by sampling the anti-phase noise at the rising edge of the clock interface PDM_CLK.

[0069] The right channel data signal is obtained by sampling the anti-phase noise at the falling edge of the data interface PDM_CLK.

[0070] The left channel data signal and the right channel data signal are multiplexed through the data interface PDM_DATA to obtain a PDM code stream data signal.

[0071] like Figure 3 As shown, it is a waveform diagram of sampling and multiplexing of a PDM interface module provided by an embodiment of the present invention.

[0072] exist Figure 3 In the figure, LEFT_CHANNEL is the left channel, RIGHT_CHANNEL is the right channel. L0 is the first data of the left channel, L1 is the second data of the left channel; R0 is the first data of the right channel, R1 is the second data of the right channel.

[0073] By analogy, L2 and R2 are the second data of the left and right channels, L3 and R3 are the third data of the left and right channels, L4 and R4 are the fourth data of the left and right channels, and L5 and R5 are the fifth data of the left and right channels. Finally, a PDM code stream data signal can be obtained.

[0074] In a specific implementation, the PDM interface module 21 samples and multiplexes the anti-phase noise through the clock interface PDM_CLK and the data interface PDM_DATA, and transmits the obtained 1-bit PDM code stream data signal of 64fs to the CIC filter, where fs is the sampling rate of the PDM interface module.

[0075] The PDM interface module 21 transmits the obtained PDM code stream data signal to the CIC filter 22 .

[0076] The input end of the CIC filter 22 is connected to the output end of the PDM interface module 21 , and the output end of the CIC filter 22 is connected to the input end of the noise shaping module 23 .

[0077] The CIC filter 22 restores the PDM code stream data signal into a first PCM data signal.

[0078] Optionally, the CIC filter 22 includes: a 3rd order CIC filter and / or a 4th order CIC filter.

[0079] In a specific implementation, if low latency is considered, the CIC filter 22 selects a 3rd-order CIC filter; if a high signal-to-noise ratio is considered, the CIC filter 22 selects a 4th-order CIC filter.

[0080] Preferably, depending on the current requirements of the low-latency noise reduction channel, a 3rd-order CIC filter and a 4th-order CIC filter may be multiplexed.

[0081] like Figure 4 The figure shows the multiplexing structure of the 3rd order CIC filter and the 4th order CIC filter. Based on the structure of the 4th order filter, an integral structure and a combing structure are removed through a mux to obtain a 3rd order CIC filter.

[0082] The transmitted 1-bit high-speed PDM code stream data signal can be converted into a first PCM data signal through the CIC filter 22. The effective bit width of the first PCM data signal is determined by the input bit width, the CIC filter order and the decimation multiple.

[0083] In a specific implementation, if the CIC filter 22 receives a 1-bit PDM code stream data signal of 64fs, the 1-bit PDM code stream data signal of 64fs is restored, and the obtained 10-bit PCM data signal of 16fs is transmitted to the noise shaping module 23 .

[0084] The CIC filter 22 transmits the converted first PCM data signal to the noise shaping module 23 .

[0085] The input end of the noise shaping module 23 is connected to the output end of the CIC filter 22 , and the output end of the noise shaping module 23 is connected to the input end of the PWM module 24 .

[0086] The noise shaping module 23 performs noise shaping and quantization processing on the first PCM data signal to obtain a second PCM data signal.

[0087] Optionally, the noise shaping module 23 includes a Delta-Sigma module (Delta-Sigma Modulation).

[0088] The Delta-Sigma module can freely configure the system through registers to obtain a better signal-to-noise ratio, and based on the signal-to-noise ratio, perform noise shaping and quantization processing on the first PCM data signal, move the first PCM data signal from low frequency to high frequency, reduce the noise in the audio band, and improve the signal-to-noise ratio of the power amplifier used subsequently.

[0089] The noise shaping module 23 transmits the second PCM data signal to the PWM module 24 .

[0090] The input end of the PWM module 24 is connected to the output end of the noise shaping module 23 , and the output end of the PWM module 24 is connected to the power amplifier device.

[0091] The PWM module 24 performs pulse width modulation on the second PCM data signal to obtain pulse data signals (PW MA and PWMB).

[0092] In a specific implementation, if the PWM module 24 receives an 8-bit data signal modulated by the noise shaping module 23 , the 8-bit data signal is compared with a reference signal, and the final comparison result is output in the form of a pulse.

[0093] The reference signal is preferably a triangular modulation signal.

[0094] like Figure 5 As shown, this is a comparison diagram when the reference signal of PWM is a triangle modulation signal.

[0095] Among them, it changes from -127 to 127, the step length of each step is 2, the input signal sampling rate is 16fs, and the 8-bit input signal (input signal) is compared with the triangle modulation signal (triangle signal). When the input signal is greater than the triangle modulation signal, the PWM outputs a high level (output signal), and when the input signal is less than the triangle modulation signal, the PWM outputs a low level (output signal).

[0096] The PWM module 24 transmits the obtained pulse data signal to the power amplifier device, which plays the pulse data signal to offset the environmental noise.

[0097] In the embodiment of the present invention, the ambient noise is processed by sound effects in an external MCU, and after a series of processing by a PDM interface module, a CIC filter, a noise shaping module and a PWM module, the obtained pulse data signal is quickly sent out to cancel the ambient noise. This process does not rely on the audio codec chip to process the ambient noise, but provides a low-latency path related to noise reduction, which not only saves the audio codec chip and many irrelevant circuits it brings, saves costs, but also achieves the purpose of low-latency noise reduction.

[0098] Based on the low-latency noise reduction circuit disclosed in the above embodiment of the present invention, the embodiment of the present invention also discloses a low-latency noise reduction method correspondingly, which is applied to the low-latency noise reduction circuit disclosed above. The low-latency noise reduction method is as follows: Figure 6 As shown, including:

[0099] S601: The MCU obtains the environmental noise received by the sound receiving device, performs inversion processing on the environmental noise, and transmits the obtained inverted noise to the PDM interface module.

[0100] S602: The PDM interface module samples and multiplexes the anti-phase noise, and transmits the obtained PDM code stream data signal to the CIC filter.

[0101] In one embodiment, the PDM interface module samples and multiplexes the anti-phase noise, and transmits the obtained 1-bit PDM code stream data signal of 64fs to the CIC filter, wherein fs is the sampling rate of the PDM interface module.

[0102] In one embodiment, the anti-phase noise is sampled based on the rising edge of the clock interface PDM_CLK of the PDM interface module to obtain the left channel data signal.

[0103] The anti-phase noise is sampled based on the falling edge of the clock interface PDM_CLK of the PDM interface module to obtain the right channel data signal.

[0104] During the sampling process, the data interface PDM_DATA of the PDM interface module is used to multiplex the sampled left channel data signal and the right channel data signal. At the end of the sampling, a PDM code stream data signal is obtained, and the obtained PDM code stream data signal is transmitted to the CIC filter.

[0105] S603: The CIC filter restores the PDM code stream data signal and transmits the obtained first PCM data signal to the noise shaping module.

[0106] In one embodiment, the CIC filter restores the 1-bit PDM code stream data signal of 64fs, and transmits the obtained 10-bit PCM data signal of 16fs to the noise shaping module.

[0107] S604: The noise shaping module performs noise shaping and quantization processing on the first PCM data signal, and transmits the obtained second PCM data signal to the PWM module.

[0108] In one embodiment, the noise shaping module performs noise shaping and quantization processing on the 10-bit PCM data signal of 16 fs, and transmits the obtained 8-bit PCM data signal of 16 fs to the PWM module.

[0109] S605: The PWM module performs pulse width modulation on the second PCM data signal, and transmits the obtained pulse data signal to the power amplifier device, which is output by the power amplifier device.

[0110] In one embodiment, the PWM module receives the second PCM data signal, and performs pulse width modulation on the second PCM data signal based on a reference signal, where the reference signal is a triangular modulation signal.

[0111] When the second PCM data signal is greater than the triangle modulation signal, the PWM module outputs a high level.

[0112] When the second PCM data signal is smaller than the triangle modulation signal, the PWM module outputs a low level.

[0113] After the pulse width modulation is completed, the PWM module sends the obtained pulse data signal to the power amplifier device, which is then output by the power amplifier device.

[0114] The specific execution process of each module involved in the low-latency noise reduction method disclosed in the embodiment of the present invention can refer to the modules in the low-latency noise reduction circuit disclosed in the above embodiment of the present invention.

[0115] In the embodiment of the present invention, the ambient noise is processed by sound effects in an external MCU, and after a series of processing by a PDM interface module, a CIC filter, a noise shaping module and a PWM module, the obtained pulse data signal is quickly sent out to cancel the ambient noise. This process does not rely on the audio codec chip to process the ambient noise, but provides a low-latency path related to noise reduction, which not only saves the audio codec chip and many irrelevant circuits it brings, saves costs, but also achieves the purpose of low-latency noise reduction.

[0116] Based on the low-latency noise reduction circuit and method disclosed in the above-mentioned embodiments of the present invention, the embodiments of the present invention further disclose an active noise reduction headset, which includes: a sound receiving device, an MCU, the low-latency noise reduction circuit disclosed in the above-mentioned embodiments of the present invention, and a power amplifier device.

[0117] The low-latency noise reduction circuit is used in the low-latency noise reduction method disclosed in the embodiment of the present invention.

[0118] It should be noted that in addition to executing the low-latency noise reduction method, the MCU also executes other related operations in the active noise reduction headphones.

[0119] In the embodiment of the present invention, a low-latency path related to noise reduction is used in the active noise reduction headphones, which can not only save the audio codec chip and many irrelevant circuits it brings, save costs, but also achieve the purpose of low-latency noise reduction.

[0120] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can refer to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiment. The system and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without creative work.

[0121] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0122] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A low-latency noise reduction circuit, characterized in that: include: MCU and noise reduction pathway; The input end of the MCU is connected to the sound receiving device, and the output end is connected to the noise reduction path. The MCU performs inversion processing on the environmental noise received by the sound receiving device and transmits the obtained inverted noise to the noise reduction path; The noise reduction path includes: a pulse density modulation PDM interface module, an integral comb CIC filter, a noise shaping module and a PWM module; The input end of the PDM interface module is connected to the output end of the MCU, and the output end is connected to the integral comb CIC filter. The PDM interface module processes the anti-phase noise to obtain a PDM code stream data signal; The output end of the integral comb CIC filter is connected to the input end of the noise shaping module, and the integral comb CIC filter restores the PDM code stream data signal to a first PCM data signal; The output end of the noise shaping module is connected to the input end of the PWM module, and the noise shaping module performs noise shaping and quantization processing on the first PCM data signal to obtain a second PCM data signal; The output end of the PWM module is connected to the power amplifier device. The PWM module performs pulse width modulation on the second PCM data signal and transmits the obtained pulse data signal to the power amplifier device.

2. The low-latency noise reduction circuit according to claim 1, characterized in that: The PDM interface module includes a clock interface PDM_CLK and a data interface PDM_DATA; The PDM code stream data includes a left channel data signal and a right channel data signal, and the left channel data signal and the right channel data signal are composed of a 1-bit data stream; The left channel data signal is obtained by sampling the anti-phase noise at the rising edge of the clock interface PDM_CLK; The right channel data signal is obtained by sampling the anti-phase noise at the falling edge of the clock interface PDM_CLK; The left channel data signal and the right channel data signal are multiplexed through the data interface PDM_DATA to obtain the PDM code stream data signal.

3. The circuit according to claim 1, characterized in that The integral comb CIC filter includes: a 3rd order CIC filter and / or a 4th order CIC filter.

4. The circuit according to claim 1, characterized in that The noise shaping module includes a Delta-Sigma module.

5. A low-latency noise reduction method, characterized in that: The low-latency noise reduction circuit applied to any one of claims 1 to 4, wherein the low-latency noise reduction method comprises: The MCU obtains the environmental noise received by the sound receiving device, performs inversion processing on the environmental noise, and transmits the obtained inverted noise to the pulse density modulation PDM interface module; The PDM interface module samples and multiplexes the anti-phase noise, and transmits the obtained PDM code stream data signal to the integral comb CIC filter; The integral comb CIC filter restores the PDM code stream data signal and transmits the obtained first PCM data signal to the noise shaping module; The noise shaping module performs noise shaping and quantization processing on the first PCM data signal, and transmits the obtained second PCM data signal to the PWM module; The PWM module performs pulse width modulation on the second PCM data signal, and transmits the obtained pulse data signal to the power amplifier device, which is then output by the power amplifier device.

6. The method according to claim 5, characterized in that The PDM interface module samples and multiplexes the anti-phase noise, and transmits the obtained PDM code stream data signal to the integral comb CIC filter, including: The PDM interface module samples and multiplexes the anti-phase noise, and transmits the obtained 1-bit PDM code stream data signal of 64fs to the integral comb CIC filter, wherein fs is the sampling rate of the PDM interface module.

7. The method according to claim 5 or 6, characterized in that: The PDM interface module samples and multiplexes the anti-phase noise, including: The anti-phase noise is sampled based on the rising edge of the clock interface PDM_CLK of the PDM interface module to obtain a left channel data signal; The anti-phase noise is sampled based on the falling edge of the clock interface PDM_CLK of the PDM interface module to obtain a right channel data signal; During the sampling process, the data interface PDM_DATA of the PDM interface module is used to multiplex the sampled left channel data signal and the right channel data signal, and at the end of the sampling, a PDM code stream data signal is obtained.

8. The method according to claim 6, characterized in that The integral comb CIC filter restores the PDM code stream data signal and transmits the obtained first PCM data signal to the noise shaping module, including: The integral comb CIC filter restores the 64fs 1-bit PDM code stream data signal and transmits the obtained 16fs 10-bit pulse code modulation PCM data signal to the noise shaping module.

9. The method according to claim 5, characterized in that The PWM module performs pulse width modulation on the second PCM data signal, and transmits the obtained pulse data signal to the power amplifier device, which is output by the power amplifier device, including: The PWM module receives the second PCM data signal and performs pulse width modulation on the second PCM data signal based on a reference signal, wherein the reference signal is a triangular modulation signal; Wherein, when the second PCM data signal is greater than the triangle modulation signal, the PWM module outputs a high level; When the second PCM data signal is smaller than the triangle modulation signal, the PWM module outputs a low level; After the pulse width modulation is completed, the PWM module sends the obtained pulse data signal to the power amplifier device, which is then output by the power amplifier device.

10. An active noise reduction headset, characterized in that: include: A radio receiver, an MCU, a power amplifier, and a low-latency noise reduction circuit as claimed in any one of claims 1 to 4.

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