Delta-sigma analog-to-digital converter with directionality and control method, hearing aid device
By integrating first and second ΔΣ modulators, delay units, and differential combination units into a ΔΣ analog-to-digital converter, directional sound pickup without relying on complex DSPs is achieved, solving the problems of high system complexity and signal loss in traditional structures, and improving the directional sound pickup capability and audio quality of audio processing.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TSINGHUA UNIVERSITY
- Filing Date
- 2026-04-24
- Publication Date
- 2026-07-14
AI Technical Summary
Traditional dual-channel ADC structures rely heavily on complex DSPs for directional sound pickup in audio processing, resulting in high system complexity, increased costs, and susceptibility to interference and signal loss during multi-stage processing.
A directional ΔΣ analog-to-digital converter is used, including first and second ΔΣ modulators, a delay unit and a differential combination unit. By converting two-channel analog signals into a single bit stream and applying an adjustable delay, the oversampling and noise shaping characteristics of ΔΣ modulation are utilized, combined with differential operations to achieve directional sound pickup, avoiding reliance on complex DSPs.
Without increasing DSP complexity, the system's directional sound pickup capability was improved, the system architecture was simplified, power consumption and cost were reduced, and audio quality was guaranteed.
Smart Images
Figure CN122394560A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of integrated circuit technology, and in particular to a directional ΔΣ analog-to-digital converter and its control method, and a hearing aid device. Background Technology
[0002] In traditional audio processing, a dual-channel ADC architecture is a common design. In this architecture, the audio signal is processed through two separate channels. The signal from each channel first passes through a comparator, outputting high-speed 1-bit data. This data then enters a digital decimation filter, ultimately outputting multi-bit, low-speed data. Because the two channel data are independent and uncorrelated, they need to be further processed by a DSP to achieve complex functions such as audio enhancement and noise suppression.
[0003] However, this traditional structure has certain limitations. On the one hand, its directional sound pickup capability heavily relies on complex subsequent DSP algorithms and processing flows. This not only increases the system's complexity and cost but also places high demands on the DSP's performance, potentially leading to increased power consumption. On the other hand, during processing, because the data needs to pass through multiple stages, the signal may be subject to a certain degree of interference and loss, affecting the final audio quality. Therefore, how to improve the system's directional sound pickup capability without relying on complex DSPs has become an urgent problem to be solved in the field of audio processing. Summary of the Invention
[0004] The purpose of this application is to provide a directional ΔΣ analog-to-digital converter and control method, as well as a hearing aid device, in order to solve the technical problem of improving the directional pickup capability of the system without relying on complex DSP.
[0005] To achieve the above objectives, this application proposes a directional ΔΣ analog-to-digital converter, which includes: a first ΔΣ modulator, a second ΔΣ modulator, a delay unit, and a differential combination unit; The first ΔΣ modulator is connected to the delay unit; the delay unit is also connected to the differential combination unit; the second ΔΣ modulator is connected to the differential combination unit; the first ΔΣ modulator and the second ΔΣ modulator are also connected to a digital decimation filter; The first ΔΣ modulator is used to receive the analog signal of the first channel and convert it into a first single-bit stream; The second ΔΣ modulator is used to receive the analog signal of the second channel and convert it into a second single-bit stream; The delay unit is used to apply an adjustable delay to the second single bit stream to obtain the delayed second single bit stream; The differential combination unit is used to perform differential operation on the first single-bit stream and the delayed second single-bit stream to output a directional digital signal.
[0006] In one embodiment, the analog signal of the first channel and the analog signal of the second channel are analog signals acquired by a pair of microphones spaced apart.
[0007] In one embodiment, the delay unit is further configured to calculate the actual delay amount in the direction of interference based on the spacing between the pair of spaced microphones, and set the adjustable delay amount as the actual delay amount.
[0008] In one embodiment, the delay unit is further configured to obtain the minimum step value of the delay amount based on the reciprocal of the modulation rate of the second ΔΣ modulator.
[0009] In one embodiment, the delay error of the adjustable delay amount is less than or equal to half of the minimum step value.
[0010] In one embodiment, the first ΔΣ modulator includes: a first integrator, a first comparator, and a first digital-to-analog converter; The first terminal of the first integrator is connected to the first terminal of the first digital-to-analog converter, and the second terminal of the first integrator is connected to the first terminal of the first comparator; the second terminal of the first comparator is grounded, and the third terminal of the first comparator is connected to the second terminal of the first digital-to-analog converter and the delay unit; the first comparator is connected to the digital decimation filter.
[0011] In one embodiment, the second ΔΣ modulator includes: a second integrator, a second comparator, and a second digital-to-analog converter; The first terminal of the second integrator is connected to the first terminal of the second digital-to-analog converter, and the second terminal of the second integrator is connected to the first terminal of the second comparator; the second terminal of the second comparator is grounded, and the third terminal of the second comparator is connected to the second terminal of the second digital-to-analog converter and the differential combination unit; the second comparator is connected to the digital decimation filter.
[0012] In addition, to achieve the above objectives, this application also proposes a hearing aid device, which includes a directional ΔΣ analog-to-digital converter as described above.
[0013] Furthermore, to achieve the above objectives, this application also proposes a control method for a directional ΔΣ analog-to-digital converter, which is applied to the hearing aid device described above; the method includes: Receive the analog signal from the first channel and convert it into a first single-bit stream; Receive the analog signal from the second channel and convert it into a second single-bit stream; Apply an adjustable delay to the second single-bit stream to obtain the delayed second single-bit stream; The first single-bit stream and the delayed second single-bit stream are differentially processed to output a directional digital signal.
[0014] In one embodiment, the step of applying an adjustable delay to the second single-bit stream to obtain the delayed second single-bit stream further includes: The actual time delay in the direction of interference is calculated based on the spacing between the pair of spaced microphones, and the adjustable delay is set as the actual time delay.
[0015] This application proposes a directional ΔΣ analog-to-digital converter and its control method, as well as a hearing aid device. The directional ΔΣ analog-to-digital converter includes: a first ΔΣ modulator, a second ΔΣ modulator, a delay unit, and a differential combination unit; the first ΔΣ modulator is connected to the delay unit; the delay unit is also connected to the differential combination unit; the second ΔΣ modulator is connected to the differential combination unit; the first ΔΣ modulator and the second ΔΣ modulator are also connected to a digital decimation filter; the first ΔΣ modulator is used to receive an analog signal from a first channel and convert it into a first single-bit stream; the second ΔΣ modulator is used to receive an analog signal from a second channel and convert it into a second single-bit stream; the delay unit is used to apply an adjustable delay to the second single-bit stream to obtain a delayed second single-bit stream; the differential combination unit is used to perform a differential operation between the first single-bit stream and the delayed second single-bit stream to output a directional digital signal. This application uses a first ΔΣ modulator and a second ΔΣ modulator to convert the two channels of analog signals into single-bit streams respectively. By utilizing the oversampling and noise shaping characteristics of ΔΣ modulation to preserve signal details and suppress quantization noise, it avoids the problem of independent and unrelated channel data in traditional structures. By applying an adjustable delay to the second single-bit stream through a delay unit, the phase difference of the target direction signal can be accurately matched, providing a basis for directional construction. Then, the two single-bit streams are differentially processed by a differential combination unit. By drawing on the principle of differential beamforming, the target direction signal is enhanced and non-target direction interference is suppressed. Directional sound pickup can be achieved without relying on subsequent complex DSP algorithms, solving the problems of high system complexity, increased cost and power consumption caused by the reliance on complex DSPs in traditional directional sound pickup structures. At the same time, this directional processing process is integrated inside the ΔΣ analog-to-digital converter, reducing interference and loss caused by signal transmission and multi-stage processing. Compared with the prior art, without increasing DSP complexity, it not only improves the system's directional sound pickup capability and ensures audio quality, but also simplifies the system architecture and reduces power consumption and cost. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the module of the first embodiment of the directional ΔΣ analog-to-digital converter proposed in this application; Figure 2 This is a circuit connection diagram of the second embodiment of the directional ΔΣ analog-to-digital converter proposed in this application; Figure 3 This is a flowchart illustrating an embodiment of the control method for a directional ΔΣ analog-to-digital converter proposed in this application.
[0017] Explanation of icon numbers:
[0018] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0019] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.
[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0021] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.
[0022] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.
[0023] Reference Figure 1 , Figure 1 This is a schematic diagram of the module of the first embodiment of the directional ΔΣ analog-to-digital converter proposed in this application. Based on Figure 1This application presents a first embodiment of a directional ΔΣ analog-to-digital converter.
[0024] The directional ΔΣ analog-to-digital converter includes: a first ΔΣ modulator 100, a second ΔΣ modulator 200, a delay unit 300, and a differential combination unit 400; the first ΔΣ modulator 100 is connected to the delay unit 300; the delay unit 300 is also connected to the differential combination unit 400; the second ΔΣ modulator 200 is connected to the differential combination unit 400; the first ΔΣ modulator 100 and the second ΔΣ modulator 200 are also connected to a digital decimation filter 500.
[0025] It should be understood that the Delta-Sigma Modulator (ΔΣ) is a high-precision analog-to-digital converter (ADC) core component, whose core principles are oversampling and noise shaping. Simply put, it doesn't directly quantize the analog signal point-by-point. Instead, it uses a sampling frequency much higher than the signal bandwidth (oversampling) to "push" the quantization error (an unavoidable precision deviation during signal conversion) to the higher frequency range of the signal (noise shaping). This significantly suppresses the impact of quantization noise on signal quality while preserving the details of the target signal, ultimately outputting a high-speed, low-precision "single-bit stream" (rather than the multi-bit data of a traditional ADC). Here, "Δ (Delta)" represents differential processing of the signal, and "Σ (Sigma)" represents integral processing of the signal; the combination of these two achieves high-precision conversion.
[0026] It should be noted that a single-bit stream is the typical output form of a ΔΣ modulator, referring to a continuous data stream consisting only of two digital states: "0" and "1". Although the information content of a single bit is limited, through the extremely high transmission rate (due to oversampling), it can indirectly carry key information such as the amplitude and phase of the analog signal. Subsequently, a high-precision multi-bit digital signal can be recovered using a digital decimation filter 500.
[0027] The first ΔΣ modulator 100 is used to receive the analog signal of the first channel and convert it into a first single-bit stream; The second ΔΣ modulator 200 is used to receive the analog signal of the second channel and convert it into a second single-bit stream.
[0028] It should be understood that the device includes two independent ΔΣ modulators (first and second ΔΣ modulators 200), each corresponding to one of the two audio input channels. The core task of the first ΔΣ modulator 100 is to receive the analog audio signal from the first channel (e.g., the sound signal from the first microphone) and convert it into a first single-bit stream using its oversampling and noise shaping functions. Correspondingly, the second ΔΣ modulator 200 receives the analog audio signal from the second channel (the sound signal from the second microphone) and similarly converts it into a second single-bit stream. This step performs the initial analog-to-digital conversion while ensuring signal quality through the characteristics of ΔΣ modulation, avoiding the problem of independent and unrelated data in traditional dual-channel structures.
[0029] The delay unit 300 is used to apply an adjustable delay to the second single bit stream to obtain the delayed second single bit stream.
[0030] It should be understood that the first single-bit stream output by the first ΔΣ modulator 100 is directly transmitted to the delay unit 300, which applies an adjustable delay. This delay can be flexibly adjusted according to the target pickup direction to ensure that the phase of the first single-bit stream matches the phase of the second single-bit stream. The delayed first single-bit stream is then transmitted to the differential combining unit 400; simultaneously, the second single-bit stream output by the second ΔΣ modulator 200 is also directly transmitted to the differential combining unit 400.
[0031] The differential combination unit 400 is used to perform differential operation on the first single bit stream and the delayed second single bit stream to output a directional digital signal.
[0032] It should be noted that after receiving these two single-bit streams, the differential combination unit 400 performs differential operations on them: for the sound signal from the target direction, since the delay unit 300 has precisely matched the phase of the two channel signals, the differential operation causes their amplitudes to superimpose and mutually enhance each other; for interference signals from other directions, since the phases cannot be matched, the differential operation causes their amplitudes to cancel each other out and mutually suppress each other. Finally, the differential combination unit 400 outputs a string of directional digital signals. This signal has completed directional sound pickup processing, retaining only the effective sound from the target direction and suppressing interference from other directions.
[0033] It should be understood that the original single-bit streams output by the first ΔΣ modulator 100 and the second ΔΣ modulator 200 are also transmitted to the digital decimation filter 500. The digital decimation filter 500 decimates and filters these two original single-bit streams, converting them into low-speed, high-precision multi-bit digital signals that can be used for subsequent audio processing (such as volume adjustment, sound quality optimization, etc.). However, this step does not affect the directional function implemented by the differential combination unit 400. The core directional pickup processing is completed inside the ΔΣ analog-to-digital converter and does not rely on an external DSP.
[0034] In this embodiment, the directional ΔΣ analog-to-digital converter includes: a first ΔΣ modulator 100, a second ΔΣ modulator 200, a delay unit 300, and a differential combination unit 400; the first ΔΣ modulator 100 is connected to the delay unit 300; the delay unit 300 is also connected to the differential combination unit 400; the second ΔΣ modulator 200 is connected to the differential combination unit 400; the first ΔΣ modulator 100 and the second ΔΣ modulator 200 are also connected to a digital decimation filter 500; the first ΔΣ modulator 100 is used to receive an analog signal from a first channel and convert it into a first single-bit stream; the second ΔΣ modulator 200 is used to receive an analog signal from a second channel and convert it into a second single-bit stream; the delay unit 300 is used to apply an adjustable delay to the second single-bit stream to obtain the delayed second single-bit stream; the differential combination unit 400 is used to perform a differential operation between the first single-bit stream and the delayed second single-bit stream to output a directional digital signal. This application uses a first ΔΣ modulator 100 and a second ΔΣ modulator 200 to convert the two channels of analog signals into single-bit streams respectively. By utilizing the oversampling and noise shaping characteristics of ΔΣ modulation, signal details are preserved and quantization noise is suppressed, avoiding the problem of independent and unrelated channel data in traditional structures. An adjustable delay is applied to the second single-bit stream through a delay unit 300, which can accurately match the phase difference of the target direction signal, providing a basis for directional construction. The differential combination unit 400 then performs differential operations on the two single-bit streams, using the principle of differential beamforming to enhance the target direction signal and suppress interference from non-target directions. Directional sound pickup can be achieved without relying on subsequent complex DSP algorithms, solving the problems of high system complexity, increased cost and power consumption caused by the reliance on complex DSPs in traditional directional sound pickup structures. At the same time, this directional processing process is integrated inside the ΔΣ analog-to-digital converter, reducing interference and loss caused by signal transmission and multi-stage processing. Compared with the prior art, without increasing DSP complexity, it not only improves the system's directional sound pickup capability and ensures audio quality, but also simplifies the system architecture and reduces power consumption and cost.
[0035] Reference Figure 2 , Figure 2 This is a schematic diagram of a second embodiment of a directional ΔΣ analog-to-digital converter (ADC) according to this application. Based on the first embodiment of the directional ΔΣ ADC described above, this application presents a second embodiment of a directional ΔΣ ADC.
[0036] The analog signal of the first channel and the analog signal of the second channel are analog signals acquired by a pair of microphones spaced apart.
[0037] It should be understood that the spacing setting refers to maintaining a certain distance between the two microphones during physical installation. This distance is not a fixed value but needs to be adapted according to the target frequency range and directional angle requirements. For example, for low-to-mid-frequency sounds (longer wavelengths), the spacing may need to be appropriately increased to obtain a significant time difference; for high-frequency sounds (shorter wavelengths), the spacing can be reduced to avoid signal distortion. The core purpose is to ensure that when sound signals from different directions reach the two microphones, they generate a phase difference that can be recognized and processed by subsequent circuits. This is the physical prerequisite for directional sound pickup. Combining the ΔΣ analog-to-digital converter workflow of the first embodiment, the analog signals collected by the two spaced microphones are input to the first ΔΣ modulator 100 and the second ΔΣ modulator 200, respectively, and converted into a first single-bit stream and a second single-bit stream. Then, the phase of one of the single-bit streams is adjusted by the delay unit 300 to cancel the time difference of the target direction sound reaching the two microphones. After processing by the differential combination unit 400, the target direction signal is enhanced and the non-target direction signal is suppressed. The basis of this entire directional processing is the dual-channel analog signal with phase difference collected by the "pair of spaced microphones". Without the microphone spacing, the two channels have no phase difference, and subsequent delay and differential processing cannot achieve a directional effect. Therefore, this acquisition method is an indispensable physical basis in the entire technical solution.
[0038] The first ΔΣ modulator 100 includes: a first integrator 101, a first comparator 102, and a first digital-to-analog converter 103.
[0039] It should be understood that the first terminal of the first integrator 101 is connected to the first terminal of the first digital-to-analog converter 103, and the second terminal of the first integrator 101 is connected to the first terminal of the first comparator 102; the second terminal of the first comparator 102 is grounded, and the third terminal of the first comparator 102 is connected to the second terminal of the first digital-to-analog converter 103 and the delay unit 300; the first comparator 102 is connected to the digital decimation filter 500.
[0040] The second ΔΣ modulator 200 includes: a second integrator 201, a second comparator 202, and a second digital-to-analog converter 203.
[0041] It should be noted that the first terminal of the second integrator 201 is connected to the first terminal of the second digital-to-analog converter 203, and the second terminal of the second integrator 201 is connected to the first terminal of the second comparator 202; the second terminal of the second comparator 202 is grounded, and the third terminal of the second comparator 202 is connected to the second terminal of the second digital-to-analog converter 203 and the differential combination unit 400; the second comparator 202 is connected to the digital decimation filter 500.
[0042] It should be understood that the mathematical model of the ΔΣ analog-to-digital converter in this scheme is: ; ; in, For the target sound source signal, The channel noise signal input to the first channel. x1(t) is the channel noise signal input to the second channel, x2(t) is the analog input signal input to the first channel, and x2(t) is the analog input signal input to the second channel. This is the propagation delay caused by the direction of the sound source.
[0043] It should be noted that the single-bit stream output from the two ΔΣ modulators can be represented as: ; ; in The quantization noise input to the first channel; The quantization noise input to the second channel; This is a single-bit stream output from the first ΔΣ modulator. This is a single-bit stream output from the second ΔΣ modulator.
[0044] The delay unit 300 is also used to calculate the actual delay amount in the direction of interference based on the spacing between the pair of spaced microphones, and set the adjustable delay amount as the actual delay amount.
[0045] It should be noted that applying a delay τ and performing differential operations in the digital domain is as follows: ; To delay, This is a single-bit stream output from the ΔΣ modulator.
[0046] Frequency domain representation is: ; The corresponding directional gain function is: ; in The spatial distance between the two channels. Let τ be the speed of sound, θ be the incident angle of the sound source, the main lobe is at θ=90° (positive side), and the null point is at θ=0° (directly in front). The pointing angle can be adjusted by τ. G(f,θ) is the directional gain function, and f is the frequency.
[0047] It should be noted that the channel spacing The calculation of sound source propagation delay, which, along with the speed of sound c, affects the calculation of the time delay, is a fundamental parameter for determining the "preset delay τ required for matching the pointing angle" (e.g., in the example, the microphone spacing d=8mm, used to calculate the actual time delay τ in the direction of interference). i , and then set τ to align with the pointing angle).
[0048] The actual time delay caused by the direction of interference is: ; The delay unit 300 is also used to obtain the minimum step value of the delay amount based on the reciprocal of the modulation rate of the second ΔΣ modulator 200.
[0049] It should be noted that setting the delay to... The minimum step size at this point is: ; The delay error of the adjustable delay amount is less than or equal to half of the minimum step value.
[0050] It should be understood that delay error can be achieved . This is the minimum delay step value. This represents the frequency corresponding to the minimum step value.
[0051] It should be noted that the residual amplitude of the interference after differential processing is approximately:
[0052] in , This represents the residual amplitude of interference after differential processing.
[0053] In this embodiment, the spatially directional ΔΣ analog-to-digital converter of this application has significant core advantages. First, it eliminates the need for complex digital signal processors. By delaying and differentially processing the dual-channel 1-bit bitstream while the sound signal is still a raw 1-bit digital pulse stream, it achieves directional enhancement during the analog-to-digital conversion stage, directly obtaining directional sound pickup capability and simplifying system design. Second, the delay adjustment is based on the high speed of the modulator, achieving a time alignment accuracy 256 times higher than the filtered solution, accurately matching the propagation delay in the target direction. Third, it exhibits outstanding interference suppression, achieving 48-60dB suppression of target interference direction in the 1-4kHz speech band, an improvement of 30-40dB compared to traditional solutions, effectively filtering irrelevant interference. Fourth, the pointing angle can be flexibly adjusted through preset delays to adapt to different scenario requirements, and the microphone spacing is on the order of millimeters, making it suitable for small audio devices such as hearing aids, with a wide range of applications.
[0054] Furthermore, this application also proposes a hearing aid device. The hearing aid device includes the aforementioned directional ΔΣ analog-to-digital converter.
[0055] Since the hearing aid device adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.
[0056] Furthermore, this application also proposes a control method for a directional ΔΣ analog-to-digital converter. (Refer to...) Figure 3 , Figure 3 This is a flowchart illustrating an embodiment of the control method for a directional ΔΣ analog-to-digital converter proposed in this application. The control method for the directional ΔΣ analog-to-digital converter includes: Step S10: Receive the analog signal from the first channel and convert it into a first single-bit stream.
[0057] It should be noted that the first channel analog signal here originates from one of the pair of spaced microphones mentioned earlier. It is a continuously changing electrical signal (such as a mixed analog signal of human voice and ambient sound from the target direction) converted from sound waves captured by that microphone. This step inputs this analog signal into the first ΔΣ modulator 100. Through the oversampling technology (sampling at a frequency much higher than the signal bandwidth) and noise shaping function of the ΔΣ modulator, the continuous analog signal is converted into a first single bit stream consisting only of "0" and "1". This conversion can preserve the effective sound information in the analog signal and transfer the quantization error (precision deviation during conversion) to the high-frequency band, reducing the impact on signal quality. At the same time, it provides a computable digital signal basis for subsequent directional processing.
[0058] Step S20: Receive the analog signal from the second channel and convert it into a second single-bit stream.
[0059] It should be understood that steps S20 and S10 are parallel dual-channel signal conversion operations, differing only in the objects they process. The received second-channel analog signal comes from another microphone spaced apart, and is also a continuous analog electrical signal containing both the target signal and interference signals. This signal is input to the second ΔΣ modulator 200, which follows the same conversion principle as the first ΔΣ modulator 100, converting the second-channel analog signal into a second single-bit stream through oversampling and noise shaping. The key significance of this step is that it ensures that the analog signals of the two channels complete the analog-to-digital conversion synchronously, and that both are output as single-bit streams, guaranteeing a unified format for the two channels. This creates conditions for subsequent delay matching and differential operations. If the conversion formats of the two channels are inconsistent or asynchronous, subsequent processing will result in signal incompatibility and phase misalignment.
[0060] Step S30: Apply an adjustable delay to the second single-bit stream to obtain the delayed second single-bit stream.
[0061] It should be understood that the delay is adjusted for the second single-bit stream output in step S20. The adjustable delay amount here is a time parameter flexibly set according to the target pickup direction (e.g., delaying by several sampling periods). Its setting is based on the time difference between the sound signal arriving at the two spaced microphones: the sound from the target direction will arrive at one microphone first, then the other. By applying a corresponding delay to the later-arriving signal (here, the second single-bit stream) through the delay unit 300, the target signals of the two channels can be aligned in time (phase matching). However, interference signals originate from non-target directions, and their arrival time difference between the two microphones differs from that of the target signal, making phase matching impossible through this delay. Therefore, the core purpose of this step is to provide a phase basis for subsequent differential operations to distinguish between the target signal and interference signals through precise delay adjustment. The adjustability of the delay amount also allows the device to adapt to different target pickup directions, improving the flexibility of directional control.
[0062] Step S40: Perform a differential operation between the first single-bit stream and the delayed second single-bit stream to output a directional digital signal.
[0063] It should be noted that in this step, the differential combination unit 400 receives two input signals: the first single-bit stream output in step S10, and the delayed second single-bit stream processed in step S30. The differential operation essentially calculates the difference between the two single-bit streams, and its core logic is based on beamforming principles: since step S30 has already matched the phases of the target signals in the two channels, the amplitudes of the target signals will be superimposed and enhanced during the differential operation; while the interference signals, due to phase mismatch, will cancel each other out and be suppressed during the differential operation. Ultimately, the digital signal output after the differential operation retains only the effective sound from the target direction, achieving directional sound pickup. This signal does not require further complex DSP processing and directly possesses directionality, simplifying the system process and reducing interference and loss during signal transmission.
[0064] The step of applying an adjustable delay to the second single-bit stream to obtain the delayed second single-bit stream further includes: calculating the true delay in the direction of interference based on the spacing between the pair of spaced microphones, and setting the adjustable delay as the true delay.
[0065] It should be noted that the logic of this supplementary step is: accurately lock onto the direction of interference → calculate its actual delay → set the corresponding delay → differential operation to cancel the interference: by using the fixed physical parameter of microphone spacing, the blind adjustment of the delay amount is avoided, making the suppression of interference signals more targeted; at the same time, since the delay amount is calculated based on the actual propagation delay, it will not affect the directional effect due to subjective adjustment deviations, which not only improves the accuracy of directional sound pickup, but also makes the entire delay setting process more scientific and repeatable. It does not rely on complex algorithm iteration optimization, and the key settings for interference suppression can be completed by calculating physical parameters alone, which further simplifies the system operation and enhances the stability of directionality.
[0066] In this embodiment, multiple significant benefits are achieved through the core logic of dual-channel signal conversion, precise delay matching, and differential operation suppression. First, without relying on complex DSP algorithms, the directional pickup function is integrated into the analog-to-digital conversion process. A ΔΣ modulator efficiently converts the analog signal to a single bitstream. The actual delay in the direction of interference is calculated based on the microphone spacing, and the delay amount is precisely set. Differential operations then specifically cancel out interference signals and enhance the target signal, significantly simplifying the system architecture and reducing hardware costs and power consumption. Second, the directional processing directly acts on the high-speed single bitstream, reducing interference and loss caused by multi-stage signal transmission and additional processing. Simultaneously, the oversampling and noise shaping characteristics of ΔΣ modulation ensure signal quality, allowing the output directional digital signal to possess both high fidelity and strong directionality. Furthermore, the delay amount is precisely calculated based on physical parameters and supports flexible adjustment, adapting to different interference directions and pickup requirements, thus improving the system's practicality and adaptability. Overall, this method solves the problem of traditional directional sound pickup relying on complex DSPs without increasing system complexity, and achieves synergistic optimization of directional accuracy, signal quality and system economy. It is suitable for various audio processing scenarios that require directional sound pickup.
[0067] The above are only some embodiments of this application and do not limit the scope of implementation of this application. Any equivalent structural or procedural transformations made based on the content of this application specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the protection scope of this application.
Claims
1. A directional ΔΣ analog-to-digital converter, characterized in that, The directional ΔΣ analog-to-digital converter includes: a first ΔΣ modulator, a second ΔΣ modulator, a delay unit, and a differential combination unit; The first ΔΣ modulator is connected to the delay unit; the delay unit is also connected to the differential combination unit; the second ΔΣ modulator is connected to the differential combination unit; the first ΔΣ modulator and the second ΔΣ modulator are also connected to a digital decimation filter; The first ΔΣ modulator is used to receive the analog signal of the first channel and convert it into a first single-bit stream; The second ΔΣ modulator is used to receive the analog signal of the second channel and convert it into a second single-bit stream; The delay unit is used to apply an adjustable delay to the second single bit stream to obtain the delayed second single bit stream; The differential combination unit is used to perform differential operation on the first single-bit stream and the delayed second single-bit stream to output a directional digital signal.
2. The directional ΔΣ analog-to-digital converter as described in claim 1, characterized in that, The analog signal of the first channel and the analog signal of the second channel are analog signals acquired by a pair of microphones spaced apart.
3. The directional ΔΣ analog-to-digital converter as described in claim 2, characterized in that, The delay unit is further configured to calculate the actual delay in the direction of interference based on the spacing between the pair of spaced microphones, and set the adjustable delay to the actual delay.
4. The directional ΔΣ analog-to-digital converter as described in claim 3, characterized in that, The delay unit is also used to obtain the minimum step value of the delay amount based on the reciprocal of the modulation rate of the second ΔΣ modulator.
5. The directional ΔΣ analog-to-digital converter as described in claim 4, characterized in that, The delay error of the adjustable delay amount is less than or equal to half of the minimum step value.
6. The directional ΔΣ analog-to-digital converter as described in claim 1, characterized in that, The first ΔΣ modulator includes: a first integrator, a first comparator, and a first digital-to-analog converter; The first terminal of the first integrator is connected to the first terminal of the first digital-to-analog converter, and the second terminal of the first integrator is connected to the first terminal of the first comparator; the second terminal of the first comparator is grounded, and the third terminal of the first comparator is connected to the second terminal of the first digital-to-analog converter and the delay unit; the first comparator is connected to the digital decimation filter.
7. The directional ΔΣ analog-to-digital converter as described in claim 1, characterized in that, The second ΔΣ modulator includes: a second integrator, a second comparator, and a second digital-to-analog converter; The first terminal of the second integrator is connected to the first terminal of the second digital-to-analog converter, and the second terminal of the second integrator is connected to the first terminal of the second comparator; the second terminal of the second comparator is grounded, and the third terminal of the second comparator is connected to the second terminal of the second digital-to-analog converter and the differential combination unit; the second comparator is connected to the digital decimation filter.
8. A hearing aid device, characterized in that, The hearing aid device includes a directional ΔΣ analog-to-digital converter as described in any one of claims 1 to 7.
9. A control method for a directional ΔΣ analog-to-digital converter, characterized in that, The method is applied to the hearing aid device as described in claim 8; the method includes: Receive the analog signal from the first channel and convert it into a first single-bit stream; Receive the analog signal from the second channel and convert it into a second single-bit stream; Apply an adjustable delay to the second single-bit stream to obtain the delayed second single-bit stream; The first single-bit stream and the delayed second single-bit stream are differentially processed to output a directional digital signal.
10. The control method for a directional ΔΣ analog-to-digital converter as described in claim 9, characterized in that, The step of applying an adjustable delay to the second single-bit stream to obtain the delayed second single-bit stream further includes: The actual time delay in the direction of interference is calculated based on the spacing between the pair of spaced microphones, and the adjustable delay is set as the actual time delay.