Signal dynamic gain control system

Abstract

The signal dynamic gain control system provided by this invention constructs an adaptive gain adjustment path through a first operational amplifier circuit and a feedback control circuit. This allows for real-time adjustment of the pre-amplification factor based on the signal strength at the front end of the analog-to-digital converter, avoiding signal overload caused by fixed gain and improving the system's adaptability to dynamic audio input. Furthermore, a comparison circuit composed of a voltage comparator and a programmable reference voltage source enables real-time judgment of high and low level logic signals, facilitating the construction of a control feedback link with a response time in the microsecond range and enhancing the system's protection sensitivity.

Description

Technical Field

[0001] This utility model relates to the field of signal processing technology, and in particular to a signal dynamic gain control system. Background Technology

[0002] Audio processing systems typically require amplification of weak audio signals during front-end signal conditioning. However, existing technologies generally employ a fixed-gain structure, which makes it highly susceptible to amplifying the signal beyond the input range of the analog-to-digital converter (ADC) in cases of sudden changes in audio signal amplitude or instability of the input source. This can lead to waveform distortion or ADC damage.

[0003] Furthermore, traditional overvoltage protection methods (such as limiting diodes or TVS devices), while ensuring protection effectiveness, have drawbacks such as large junction capacitance and limited bandwidth, making them unsuitable for high-fidelity audio systems. Some systems employ clipping or limiting circuits, but these methods cause harmonic distortion and cannot meet the requirements of high dynamic range audio processing.

[0004] In summary, the problems existing in the current technology urgently need to be solved. Utility Model Content

[0005] This invention provides a dynamic gain control system for signals to overcome the shortcomings of the prior art, realize real-time adjustment of the preamplifier gain, avoid signal overload caused by fixed gain, and improve the system's adaptability to dynamic audio input.

[0006] This utility model provides a signal dynamic gain control system, including:

[0007] The circuit consists of a first operational amplifier circuit, a second operational amplifier circuit, an analog-to-digital converter, a signal acquisition module, a comparison circuit, and a feedback control circuit.

[0008] The first operational amplifier circuit has its input terminal connected to the signal input terminal and is used to amplify the input audio signal in the first stage.

[0009] The second operational amplifier circuit has its input terminal connected to the output terminal of the first operational amplifier circuit, and is used to amplify the audio signal in a second stage.

[0010] The analog-to-digital converter has its input terminal connected to the output terminal of the second operational amplifier circuit, and is used to sample the amplified audio signal;

[0011] The signal acquisition module has its input terminal connected to the output terminal of the second operational amplifier circuit, and is used to acquire the analog signal provided to the analog-to-digital converter;

[0012] The comparison circuit has its input terminal connected to the signal acquisition module, and is used to compare the acquired analog signal with a preset reference value and output the comparison result.

[0013] The feedback control circuit has its input terminal connected to the comparison circuit, and is used to generate a feedback control signal based on the comparison result.

[0014] The output of the feedback control circuit is connected to the first operational amplifier circuit and is used to adjust the gain of the first operational amplifier circuit.

[0015] According to the signal dynamic gain control system provided by this utility model, the first operational amplifier circuit includes:

[0016] A set of input resistors and feedback resistors are used to construct the closed-loop gain path of the operational amplifier. The feedback resistor is connected between the output terminal and the inverting input terminal of the operational amplifier, and the input resistor is connected between the signal input terminal and the inverting input terminal.

[0017] The feedback resistor is composed of multiple resistive elements and a controllable switch array, with each resistive element connected to a corresponding controllable switch;

[0018] The feedback control circuit is connected to the switch array and is used to output control signals to control the conduction or disconnection of the corresponding switches, so that the resistance value of the closed-loop feedback path of the operational amplifier can be adjusted by selecting different resistor combinations.

[0019] According to the signal dynamic gain control system provided by this utility model, the controllable switch array is a MOSFET switch circuit.

[0020] According to the signal dynamic gain control system provided by this utility model, the second operational amplifier circuit adopts a differential input structure, including:

[0021] A pair of symmetrical input ports, one for positive input and one for negative input;

[0022] A symmetrically configured network of input matching resistors is used to receive the positive and negative output signals of the first operational amplifier circuit.

[0023] According to the present invention, a signal dynamic gain control system is provided, wherein the signal acquisition module includes: a voltage divider circuit, a sampling capacitor, and a buffer amplifier;

[0024] The voltage divider circuit has its input terminal connected to the output terminal of the second operational amplifier circuit, and is used to attenuate the signal to a preset range.

[0025] The sampling capacitor is connected to the output node of the voltage divider circuit to stabilize the sampling signal and suppress transient noise.

[0026] The buffer amplifier has its input connected to the sampling node and its output connected to the comparison circuit, and is used to provide voltage buffering.

[0027] According to the signal dynamic gain control system provided by this utility model, the comparison circuit includes a voltage comparator;

[0028] The positive input terminal of the voltage comparator is connected to the output of the signal acquisition module, and the negative input terminal is connected to the reference voltage source.

[0029] The voltage comparator is used to compare the acquired signal with the reference voltage in real time. When the sampled signal is higher or lower than the reference voltage, it outputs a corresponding high-level or low-level digital control signal as the input basis for the feedback control circuit.

[0030] According to the signal dynamic gain control system provided by this utility model, the reference voltage source includes a reference voltage chip and a digital-to-analog converter;

[0031] The reference voltage chip is used to provide a stable reference base voltage;

[0032] The digital-to-analog converter is used to receive digital signals set by an external controller, convert them into analog reference voltages, and output them to the negative input terminal of the voltage comparator.

[0033] According to the present invention, a signal dynamic gain control system includes a feedback control circuit comprising a low-pass filter circuit and a control logic module.

[0034] The low-pass filter circuit has its input connected to the output of the comparison circuit, and is used to smooth the comparison result to filter out high-frequency spikes.

[0035] The control logic module has its input terminal connected to the output terminal of the low-pass filter circuit and its output terminal connected to the first operational amplifier circuit, and is used to generate feedback control commands based on the stable filtered signal.

[0036] According to the signal dynamic gain control system provided by this utility model, the feedback control circuit further includes: a PWM modulator and a voltage control amplifier;

[0037] The PWM modulator has its input terminal connected to the output terminal of the comparison circuit, and its output terminal generates a PWM waveform.

[0038] The PWM signal is used to control the amplification factor of the voltage-controlled amplifier.

[0039] According to the signal dynamic gain control system provided by this utility model, a voltage isolation buffer circuit is provided between the first operational amplifier circuit and the feedback control circuit.

[0040] The voltage isolation buffer circuit receives the adjustment signal from the feedback control circuit at its input terminal and drives the feedback adjustment path in the first operational amplifier circuit at its output terminal, in order to prevent the control signal from interfering with the operational amplifier signal path in reverse.

[0041] The signal dynamic gain control system provided by this invention constructs an adaptive gain adjustment path through a first operational amplifier circuit and a feedback control circuit. This allows for real-time adjustment of the pre-amplification factor based on the signal strength at the front end of the analog-to-digital converter, avoiding signal overload caused by fixed gain and improving the system's adaptability to dynamic audio input. Furthermore, a comparison circuit composed of a voltage comparator and a programmable reference voltage source enables real-time judgment of high and low level logic signals, facilitating the construction of a control feedback link with a response time in the microsecond range and enhancing the system's protection sensitivity. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0043] Figure 1 This is a schematic diagram of the module of the signal dynamic gain control system provided by this utility model. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0045] To address the problems in existing technologies, this invention proposes a dynamic signal gain control system to achieve real-time adjustment of the preamplifier gain, avoid signal overload caused by fixed gain, and improve the system's adaptability to dynamic audio input. The dynamic signal gain control system is described below, as follows: Figure 1 As shown, including but not limited to the following modules:

[0046] The circuit consists of a first operational amplifier circuit, a second operational amplifier circuit, an analog-to-digital converter, a signal acquisition module, a comparison circuit, and a feedback control circuit.

[0047] The first operational amplifier circuit has its input terminal connected to the signal input terminal and is used to amplify the input audio signal in the first stage.

[0048] The second operational amplifier circuit has its input terminal connected to the output terminal of the first operational amplifier circuit, and is used to amplify the audio signal in a second stage.

[0049] The analog-to-digital converter has its input terminal connected to the output terminal of the second operational amplifier circuit, and is used to sample the amplified audio signal;

[0050] The signal acquisition module has its input terminal connected to the output terminal of the second operational amplifier circuit, and is used to acquire the analog signal provided to the analog-to-digital converter;

[0051] The comparison circuit has its input terminal connected to the signal acquisition module, and is used to compare the acquired analog signal with a preset reference value and output the comparison result.

[0052] The feedback control circuit has its input terminal connected to the comparison circuit, and is used to generate a feedback control signal based on the comparison result.

[0053] The output of the feedback control circuit is connected to the first operational amplifier circuit and is used to adjust the gain of the first operational amplifier circuit.

[0054] Specifically, the input terminal of the first operational amplifier circuit is connected to the audio signal input terminal of the system, and is mainly used for the first stage amplification of the original input signal. The first operational amplifier circuit adopts an inverting amplification structure, and its input terminal is equipped with an input resistor. A set of adjustable feedback resistors is connected in the feedback loop. This set of feedback resistors is composed of multiple fixed resistors connected in series or parallel and a MOSFET switch array. The combination state of the feedback resistors is controlled by a feedback control circuit, thereby realizing the dynamic adjustment of the amplification factor.

[0055] The input of the second operational amplifier circuit is connected to the output of the first operational amplifier circuit, and is used to further amplify the signal after the first stage of amplification. Preferably, the second operational amplifier circuit adopts a differential input structure, which has high common-mode rejection capability and is suitable for improving the system's anti-interference capability. The output of this circuit also serves as the signal source for subsequent analog-to-digital converters and signal acquisition modules.

[0056] The input of the analog-to-digital converter (ADC) is connected to the output of the second operational amplifier circuit to convert the amplified analog audio signal into a digital signal. To ensure that the signal does not exceed the full-scale input range of the ADC, the system needs to control the gain of the preceding stage in real time to prevent waveform clipping or device damage caused by excessive input voltage.

[0057] The input of the signal acquisition module is also connected to the output of the second operational amplifier circuit. This module includes a voltage divider circuit, a sampling capacitor, and a buffer amplifier. The voltage divider circuit attenuates the signal appropriately, the sampling capacitor filters out high-frequency interference, and the buffer amplifier outputs a stable level signal to the subsequent comparison circuit, avoiding load interference to the previous stage signal channel.

[0058] The comparison circuit is used to compare the sampled signal with a system-set reference voltage in real time. In this embodiment, the comparison circuit uses a high-precision voltage comparator, whose positive input is connected to the output of the signal acquisition module, and whose negative input is connected to an adjustable reference voltage provided by a reference voltage source (such as a reference voltage chip with a digital-to-analog converter). The voltage comparator compares the two and outputs a high or low level as the comparison result, which is used to determine whether the signal is too high or too low.

[0059] The input of the feedback control circuit is connected to the output of the comparator circuit, receiving the comparison result from the voltage comparator. This control circuit may include a low-pass filter module to filter out signal glitches, and a control logic module to generate control commands based on the comparison result. The control commands act on the feedback resistor switch array of the first operational amplifier circuit, thereby dynamically adjusting the closed-loop gain, reducing the input signal amplitude, and ensuring system stability.

[0060] The specific workflow is as follows: When the amplitude of the input audio signal is small, the comparator circuit outputs a low level, and the feedback control circuit increases the gain of the first operational amplifier circuit to enhance the weak signal; when the amplitude of the input signal rises to near the upper limit of the ADC, the comparator circuit outputs a high level, and the feedback control circuit immediately reduces the gain of the first operational amplifier circuit to ensure that the ADC input level is maintained within a safe range, thereby achieving the dual goals of dynamic range optimization and device protection.

[0061] In summary, this embodiment achieves dynamic adjustment of audio signal gain through a closed-loop control path of operational amplifier-sampling-comparison-feedback, avoiding the ADC overload problem caused by fixed gain in traditional systems, and enhancing the system's adaptability to different signal sources and noise environments.

[0062] As a further optional embodiment, the first operational amplifier circuit includes:

[0063] A set of input resistors and feedback resistors are used to construct the closed-loop gain path of the operational amplifier. The feedback resistor is connected between the output terminal and the inverting input terminal of the operational amplifier, and the input resistor is connected between the signal input terminal and the inverting input terminal.

[0064] The feedback resistor is composed of multiple resistive elements and a controllable switch array, with each resistive element connected to a corresponding controllable switch;

[0065] The feedback control circuit is connected to the switch array and is used to output control signals to control the conduction or disconnection of the corresponding switches, so that the resistance value of the closed-loop feedback path of the operational amplifier can be adjusted by selecting different resistor combinations.

[0066] In an optional embodiment, to achieve discretely adjustable audio signal gain, the first operational amplifier circuit in this invention employs a modular gain structure, which specifically includes:

[0067] Input resistance and feedback resistance pair:

[0068] The first operational amplifier circuit is an inverting amplifier structure, with a set of input resistors and a feedback resistor. The input resistor is connected between the audio signal input terminal and the inverting input terminal of the operational amplifier; the feedback resistor is connected between the output terminal and the inverting input terminal of the operational amplifier to form a typical closed-loop amplification path.

[0069] Multi-stage feedback resistors and controllable switch arrays:

[0070] The feedback resistor is not a single resistor, but rather consists of multiple fixed-value resistive elements and a controllable switch array. Each resistive element is connected in series with a corresponding MOSFET, CMOS switch, or relay switch, and the conduction state of each switch is determined by an external control signal. By combining the on / off states of different resistive elements, the equivalent resistance of the overall feedback path is changed, thereby dynamically adjusting the closed-loop gain of this operational amplifier stage.

[0071] Control method of feedback control circuit:

[0072] The feedback control circuit is connected to the aforementioned controllable switch array. The feedback control circuit receives the output from the comparison circuit and outputs multiple control signals based on the signal strength. These control signals drive corresponding switches to turn on or off, allowing different resistor units in the feedback path to be selected or bypassed, thereby achieving discrete-stage adjustment of the operational amplifier gain. For example, it can be set to multiple levels such as 1x, 2x, 4x, and 8x, or further refined into a continuously adjustable mode.

[0073] In this embodiment, compared to the traditional gain amplifier structure with a fixed feedback resistor, this adjustable feedback circuit has higher adaptability and flexibility. Through digital control of the feedback loop, the operational amplifier gain can be adjusted in real time according to the actual changes in the audio input signal level without changing the hardware structure. This effectively improves the system's ability to handle different audio source environments, prevents ADC overvoltage, and preserves the dynamic characteristics and waveform integrity of the audio signal.

[0074] As a further optional embodiment, the controllable switch array is a MOSFET switching circuit.

[0075] In one optional embodiment, the controllable switch array in the first operational amplifier circuit is specifically implemented as a MOSFET switch circuit, used for selecting and controlling the resistance combination in the feedback resistor network.

[0076] The MOSFET switching circuit includes multiple N-channel or P-channel metal-oxide-semiconductor field-effect transistors (MOSFETs). The source and drain of each MOSFET are connected in series across a feedback resistor of a preset resistance value, and the gate is connected to the control signal channel output by the feedback control circuit.

[0077] When a high level (or low level, depending on the MOSFET type) is applied to the gate of a MOSFET, the MOSFET is turned on, and the corresponding feedback resistor is effectively connected to the closed-loop path; when the control signal is low, the MOSFET is turned off, and the corresponding feedback resistor is bypassed or disconnected, thus not affecting the total feedback resistance value.

[0078] By combining and controlling the aforementioned multiple MOSFETs, multi-level closed-loop gain control can be achieved.

[0079] As a further optional embodiment, the second operational amplifier circuit adopts a differential input structure, including:

[0080] A pair of symmetrical input ports, one for positive input and one for negative input;

[0081] A symmetrically configured network of input matching resistors is used to receive the positive and negative output signals of the first operational amplifier circuit.

[0082] In one optional embodiment, the second operational amplifier circuit adopts a differential input structure to enhance the anti-interference capability and signal fidelity during audio signal processing, and is particularly suitable for long-distance transmission or low-level signal scenarios.

[0083] Specifically, the second operational amplifier circuit includes:

[0084] A pair of symmetrical input ports, namely a positive input terminal (+) and a negative input terminal (−), are used to receive differential signal input;

[0085] A symmetrically configured network of input matching resistors, including a first matching resistor and a second matching resistor, is connected in series between the positive and negative output terminals of the first operational amplifier circuit and the positive and negative input terminals of the second operational amplifier circuit, respectively.

[0086] In this embodiment, the first operational amplifier circuit is configured as a differential output structure, or it is connected to a differential driver module so that its output is a pair of differential audio signals (+Vin and −Vin) with opposite polarities and equal amplitudes.

[0087] The function of the input matching resistor network is:

[0088] Ensure impedance symmetry at the two input terminals of the differential amplifier to improve the common-mode rejection ratio (CMRR).

[0089] Control the amplitude range of the input signal to prevent distortion of the second operational amplifier circuit due to excessively high levels;

[0090] Reduce the impact of the signal source output impedance on the linearity of the input signal.

[0091] Through the aforementioned differential structure, the second operational amplifier circuit can effectively suppress common-mode noise caused by electromagnetic interference, ground potential difference, or transmission line imbalance, achieving high-fidelity amplification of audio signals, which is beneficial for improving the quantization accuracy in the subsequent analog-to-digital conversion process.

[0092] In addition, if the first operational amplifier circuit itself is a single-ended output, an inverting signal generation circuit (such as an inverter) or a differential buffer can be introduced after it to achieve a virtual differential output, thereby making it compatible with this differential input amplifier structure.

[0093] In summary, this differential input structure not only enhances the anti-interference capability of the signal path, but also provides the system as a whole with stronger versatility and signal-to-noise ratio performance.

[0094] As a further optional embodiment, the signal acquisition module includes: a voltage divider circuit, a sampling capacitor, and a buffer amplifier;

[0095] The voltage divider circuit has its input terminal connected to the output terminal of the second operational amplifier circuit, and is used to attenuate the signal to a preset range.

[0096] The sampling capacitor is connected to the output node of the voltage divider circuit to stabilize the sampling signal and suppress transient noise.

[0097] The buffer amplifier has its input connected to the sampling node and its output connected to the comparison circuit, and is used to provide voltage buffering.

[0098] In this embodiment, the input terminal of the voltage divider circuit is connected to the output terminal of the second operational amplifier circuit. Its main function is to perform amplitude attenuation processing on the amplified audio signal, so that the signal voltage is limited to a controllable and safe preset range to adapt to the input voltage range of the subsequent comparison circuit or digital-to-analog interface.

[0099] In practical implementation, the voltage divider circuit can be a simple RC voltage divider composed of a pair of series resistors, or a multi-stage adjustable resistor network can be introduced to support the input requirements of different ADCs or comparison circuits.

[0100] The sampling capacitor is connected to the output node of the voltage divider circuit to temporarily store the sampled charge, enabling the analog voltage hold function while suppressing transient spike noise in the input signal. The presence of this capacitor significantly improves the stability of the sampled signal and its resistance to high-frequency interference, making it particularly suitable for scenarios where the audio input signal contains pulse or abrupt changes.

[0101] Preferably, the capacitance value of the sampling capacitor is designed based on the signal frequency characteristics and response time requirements, typically ranging from tens of picofarads (pF) to hundreds of nanofarads (nF).

[0102] The input of the buffer amplifier is connected to the sampling node (i.e., the capacitor output), and the output is connected to the comparator circuit. The buffer amplifier is used to isolate the load effect between the front-end sampling network and the subsequent circuit. Its internal structure can be a unity-gain follower (such as an emitter follower or non-inverting operational amplifier configuration), which has the characteristics of high input impedance and low output impedance.

[0103] The buffer amplifier ensures that the voltage signal at the sampling node is not disturbed or pulled low during transmission to the comparison circuit, thereby improving sampling accuracy and system feedback stability.

[0104] Through the collaborative design of the above structure, the signal acquisition module can effectively attenuate, stabilize and buffer the analog signal output by the second-stage operational amplifier, providing an accurate and low-noise sampling basis for subsequent reference comparison and gain adjustment, and improving the robustness and dynamic response capability of the overall system.

[0105] As a further optional embodiment, the comparison circuit includes a voltage comparator;

[0106] The positive input terminal of the voltage comparator is connected to the output of the signal acquisition module, and the negative input terminal is connected to the reference voltage source.

[0107] The voltage comparator is used to compare the acquired signal with the reference voltage in real time. When the sampled signal is higher or lower than the reference voltage, it outputs a corresponding high-level or low-level digital control signal as the input basis for the feedback control circuit.

[0108] In one optional embodiment, the comparison circuit adopts a voltage comparator-based structure design, which has high-speed response capability and is suitable for real-time detection of whether the amplitude of the analog sampling signal exceeds a preset reference range.

[0109] Specifically:

[0110] The positive input terminal of the voltage comparator is connected to the output of the signal acquisition module to receive the sampled signal after voltage division, filtering and buffering.

[0111] The negative input of the voltage comparator is connected to a stable reference voltage source, which can be preset according to the full-scale input range of the ADC (e.g., 2.8V in a 3.3V system or 90% of the full-scale voltage).

[0112] The voltage comparator is used to compare the two voltage signals in real time and output the corresponding digital control level based on the result.

[0113] Through the above design, the voltage comparator ensures the safety of the ADC input without affecting the spectral structure and distortion characteristics of the original audio signal.

[0114] As a further optional embodiment, the reference voltage source includes a reference voltage chip and a digital-to-analog converter;

[0115] The reference voltage chip is used to provide a stable reference base voltage;

[0116] The digital-to-analog converter is used to receive digital signals set by an external controller, convert them into analog reference voltages, and output them to the negative input terminal of the voltage comparator.

[0117] In a further optional embodiment, to enable flexible control of the voltage comparator reference, the reference voltage source includes:

[0118] A reference voltage chip is used to provide a fixed reference voltage with low temperature drift and high stability;

[0119] A digital-to-analog converter is used to convert a set digital quantity into the required analog voltage output according to the input instructions of an external controller.

[0120] The reference voltage chip can be a conventional precision voltage source chip such as 1.25V, 2.5V, or 3.3V, such as TILM4040 or Analog AD584. Its output voltage is filtered and provided to the DAC as a reference input.

[0121] The digital-to-analog converter communicates with the system controller (such as an MCU, DSP, or FPGA) and can use I²C, SPI, or parallel port protocols. It supports multiple precisions (such as 8-bit, 10-bit, and 12-bit) and is used to convert the digital set value output by the controller into an adjustable analog voltage output. This voltage is then provided to the negative input of the voltage comparator as a reference.

[0122] In summary, the combined design of the reference voltage source combines stability and adjustability, providing the system with a flexible and accurate comparison control benchmark, and is a key auxiliary control module for the dynamic gain adjustment system.

[0123] As a further optional embodiment, the feedback control circuit includes: a low-pass filter circuit and a control logic module;

[0124] The low-pass filter circuit has its input connected to the output of the comparison circuit, and is used to smooth the comparison result to filter out high-frequency spikes.

[0125] The control logic module has its input terminal connected to the output terminal of the low-pass filter circuit and its output terminal connected to the first operational amplifier circuit, and is used to generate feedback control commands based on the stable filtered signal.

[0126] In a further optional embodiment, to improve the accuracy of the system's judgment of sudden signals and the stability of the feedback control, the feedback control circuit includes: a low-pass filter circuit; and a control logic module.

[0127] The input of the low-pass filter circuit is connected to the output of the comparator circuit. It is used to filter the rapidly changing digital signal output by the voltage comparator, suppress high-frequency spikes or jitter, and thus avoid false feedback control triggered by transient interference or high-frequency noise.

[0128] This filtering circuit can be constructed using an RC passive filter or an active filter built from an operational amplifier. Its cutoff frequency is optimized based on the characteristics of the audio input signal and the response time of the control system. For example, when the system is expected to respond only to effective frequency variations below 10 kHz, the cutoff frequency can be set to several hundred Hz.

[0129] In addition, simple digital filtering algorithms (such as moving average, exponential decay filtering, etc.) can be introduced into the filter circuit to further improve its robustness.

[0130] The input terminal of the control logic module is connected to the output terminal of the low-pass filter circuit to receive the smoothed judgment signal; the output terminal is connected to the first operational amplifier circuit to drive its feedback network, thereby realizing dynamic gain adjustment control.

[0131] The control logic module can be implemented in one of the following forms:

[0132] Programmable logic devices (such as FPGAs and CPLDs);

[0133] Microcontrollers (such as STM32, PIC);

[0134] Fixed logic circuits (such as combinational logic gates and state machines);

[0135] Its functions include:

[0136] Determine whether the gain adjustment trigger threshold has been reached based on the filtered signal;

[0137] Control the conduction state of the MOSFET switch array on the feedback resistor of the first operational amplifier;

[0138] Implement logic to gradually increase or decrease gain (e.g., single jump, graded response, or PWM regulation);

[0139] Preserve the gain state to avoid repeated jitter.

[0140] For example, if the low-pass filtered control signal remains high for more than a set time (e.g., 10ms), the control logic outputs a signal with a decreased gain; conversely, if the signal remains below the reference level for an extended period, the feedback path is allowed to switch to a larger resistance value to increase the signal amplitude.

[0141] With the above structure, the feedback control circuit has the advantages of anti-interference, high stability, and smooth adjustment response, avoiding the problem of misjudging gain changes caused by instantaneous noise, and effectively improving the accuracy of dynamic processing of audio signals and the overall performance of the system.

[0142] As a further optional embodiment, the feedback control circuit further includes: a PWM modulator and a voltage control amplifier;

[0143] The PWM modulator has its input terminal connected to the output terminal of the comparison circuit, and its output terminal generates a PWM waveform.

[0144] The PWM signal is used to control the amplification factor of the voltage-controlled amplifier.

[0145] In another optional embodiment, to achieve continuously adjustable control of the gain of the first operational amplifier circuit and improve the response accuracy and analog consistency of the system, the feedback control circuit further includes: a PWM modulator; and a voltage control amplifier.

[0146] The input terminal of the PWM modulator is connected to the output terminal of the comparison circuit to receive the logic control signal (such as high level / low level or multi-bit data signal) output by the voltage comparator, and to generate a PWM waveform signal with a variable duty cycle in real time according to the input signal.

[0147] The duty cycle of this PWM signal represents the required level of gain adjustment. For example, a 90% duty cycle indicates that the current input signal amplitude is high, requiring a significant reduction in gain; while a 10% duty cycle indicates that the input signal is low, requiring an appropriate increase in gain.

[0148] The frequency selection of the PWM signal needs to take into account both the system response speed and the filtering capability of the voltage control amplifier, and is usually selected in the range of tens of kHz to hundreds of kHz.

[0149] The control terminal of the voltage-controlled amplifier is connected to the output terminal of the PWM modulator, and its gain is determined by the average voltage of the PWM signal (after low-pass filtering).

[0150] In this embodiment, the PWM signal is converted into a constant level control voltage (DClevel) after passing through an RC low-pass filter. This voltage is input to the VCA control pin to dynamically adjust the amplification factor.

[0151] VCA can be built using integrated chips (such as THAT2180, LM13700, SSM2164) or by using operational amplifiers and JFET / MOS transistors to construct an analog variable gain unit.

[0152] The signal input terminal of the voltage-controlled amplifier is connected to the output of the first operational amplifier circuit, and the output terminal serves as the final controllable output interface of the system. It can also be connected to the second operational amplifier circuit for subsequent processing.

[0153] As a further optional embodiment, a voltage isolation buffer circuit is provided between the first operational amplifier circuit and the feedback control circuit;

[0154] The voltage isolation buffer circuit receives the adjustment signal from the feedback control circuit at its input terminal and drives the feedback adjustment path in the first operational amplifier circuit at its output terminal, in order to prevent the control signal from interfering with the operational amplifier signal path in reverse.

[0155] In a further optional embodiment, to prevent signal crosstalk, logic jitter, or level interference caused when the feedback control signal directly acts on the first operational amplifier circuit, a voltage isolation buffer circuit is provided between the first operational amplifier circuit and the feedback control circuit in the system.

[0156] This buffer circuit is used to isolate and amplify or level-shift control signals, thereby improving system stability, reducing feedback interference, and ensuring the purity and accuracy of the operational amplifier's main signal path.

[0157] The voltage isolation buffer circuit provides a highly robust and precise signal control path in the system, effectively ensuring the electrical integrity between the main signal chain and the control chain during gain adjustment.

[0158] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A signal dynamic gain control system, characterized in that, include: The circuit consists of a first operational amplifier circuit, a second operational amplifier circuit, an analog-to-digital converter, a signal acquisition module, a comparison circuit, and a feedback control circuit. The first operational amplifier circuit has its input terminal connected to the signal input terminal and is used to amplify the input audio signal in the first stage. The second operational amplifier circuit has its input terminal connected to the output terminal of the first operational amplifier circuit, and is used to amplify the audio signal in a second stage. The analog-to-digital converter has its input terminal connected to the output terminal of the second operational amplifier circuit, and is used to sample the amplified audio signal; The signal acquisition module has its input terminal connected to the output terminal of the second operational amplifier circuit, and is used to acquire the analog signal provided to the analog-to-digital converter; The comparison circuit has its input terminal connected to the signal acquisition module, and is used to compare the acquired analog signal with a preset reference value and output the comparison result. The feedback control circuit has its input terminal connected to the comparison circuit, and is used to generate a feedback control signal based on the comparison result. The output of the feedback control circuit is connected to the first operational amplifier circuit and is used to adjust the gain of the first operational amplifier circuit.

2. The signal dynamic gain control system according to claim 1, characterized in that, The first operational amplifier circuit includes: A set of input resistors and feedback resistors are used to construct the closed-loop gain path of the operational amplifier. The feedback resistor is connected between the output terminal and the inverting input terminal of the operational amplifier, and the input resistor is connected between the signal input terminal and the inverting input terminal. The feedback resistor is composed of multiple resistive elements and a controllable switch array, with each resistive element connected to a corresponding controllable switch; The feedback control circuit is connected to the switch array and is used to output control signals to control the conduction or disconnection of the corresponding switches, so that the resistance value of the closed-loop feedback path of the operational amplifier can be adjusted by selecting different resistor combinations.

3. The signal dynamic gain control system according to claim 2, characterized in that, The controllable switch array is a MOSFET switching circuit.

4. The signal dynamic gain control system according to claim 1, characterized in that, The second operational amplifier circuit adopts a differential input structure, including: A pair of symmetrical input ports, one for positive input and one for negative input; A symmetrically configured network of input matching resistors is used to receive the positive and negative output signals of the first operational amplifier circuit.

5. The signal dynamic gain control system according to claim 1, characterized in that, The signal acquisition module includes: a voltage divider circuit, a sampling capacitor, and a buffer amplifier; The voltage divider circuit has its input terminal connected to the output terminal of the second operational amplifier circuit, and is used to attenuate the signal to a preset range. The sampling capacitor is connected to the output node of the voltage divider circuit to stabilize the sampling signal and suppress transient noise. The buffer amplifier has its input connected to the sampling node and its output connected to the comparison circuit, and is used to provide voltage buffering.

6. The signal dynamic gain control system according to claim 1, characterized in that, The comparison circuit includes a voltage comparator; The positive input terminal of the voltage comparator is connected to the output of the signal acquisition module, and the negative input terminal is connected to the reference voltage source. The voltage comparator is used to compare the acquired signal with the reference voltage in real time. When the sampled signal is higher or lower than the reference voltage, it outputs a corresponding high-level or low-level digital control signal as the input basis for the feedback control circuit.

7. The signal dynamic gain control system according to claim 6, characterized in that, The reference voltage source includes a reference voltage chip and a digital-to-analog converter; The reference voltage chip is used to provide a stable reference base voltage; The digital-to-analog converter is used to receive digital signals set by an external controller, convert them into analog reference voltages, and output them to the negative input terminal of the voltage comparator.

8. The signal dynamic gain control system according to claim 1, characterized in that, The feedback control circuit includes: a low-pass filter circuit and a control logic module; The low-pass filter circuit has its input connected to the output of the comparison circuit, and is used to smooth the comparison result to filter out high-frequency spikes. The control logic module has its input terminal connected to the output terminal of the low-pass filter circuit and its output terminal connected to the first operational amplifier circuit, and is used to generate feedback control commands based on the stable filtered signal.

9. The signal dynamic gain control system according to claim 1, characterized in that, The feedback control circuit also includes: a PWM modulator and a voltage control amplifier; The PWM modulator has its input terminal connected to the output terminal of the comparison circuit, and its output terminal generates a PWM signal. The PWM signal is used to control the amplification factor of the voltage-controlled amplifier.

10. The signal dynamic gain control system according to claim 1, characterized in that, A voltage isolation buffer circuit is provided between the first operational amplifier circuit and the feedback control circuit; The voltage isolation buffer circuit receives the adjustment signal from the feedback control circuit at its input terminal and drives the feedback adjustment path in the first operational amplifier circuit at its output terminal, in order to prevent the control signal from interfering with the operational amplifier signal path in reverse.

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