Time division multiplexed analog filtering system

Abstract

The application provides a time division multiplexing analog filtering system. The system comprises a digital system, a first digital-to-analog converter connected with the digital system and used for converting a digital signal into a plurality of analog signals, a timing control circuit, an input port of the timing control circuit being connected with the digital system, an output port of the timing control circuit being connected with an analog filter, and the timing control circuit being used for time-divisionally outputting a plurality of analog control voltages to the analog filter, the analog filter being used for filtering the plurality of analog signals based on the plurality of analog control voltages, and an analog-to-digital converter connected with the analog filter, used for converting the plurality of analog signals filtered into digital signals and inputting the digital signals into the digital system. By embedding the analog filtering system in the digital system, the problem of insufficient timbre restoration in the prior art is solved, and by time-divisionally outputting adaptive analog control voltages to the analog filter through the timing control circuit, real-time control of the analog timbre is improved.

Description

Technical Field

[0001] This application belongs to the field of signal processing technology and relates to a time-division multiplexing analog filtering system. Background Technology

[0002] Existing digital synthesizers have significant advantages in polyphonic performance, synthesis technology flexibility, convenient timbre storage and system scalability, but they are still inherently limited by the physical characteristics of digital signal processing. They are unable to accurately reproduce the harmonic saturation characteristics unique to analog filter circuits and other physical characteristics that are difficult to realize digitally, resulting in poor timbre reproduction.

[0003] Therefore, improving the sound reproduction accuracy of digital systems has become an urgent technical problem to be solved. Utility Model Content

[0004] This application provides a time-division multiplexing analog filtering system for improving the timbre reproduction of digital systems.

[0005] In a first aspect, this application provides a time-division multiplexing analog filtering system, characterized in that the system comprises:

[0006] A digital system includes digital signals; a first digital-to-analog converter connected to the digital system for converting the digital signals into multiple analog signals; a timing control circuit module, the input port of which is connected to the digital system and the output port of which is connected to an analog filter for time-division multiplexing of multi-channel analog control voltages to achieve more channels of output; an analog filter for filtering the multiple analog signals using the multi-channel analog control voltages; and an analog-to-digital converter connected to the analog filter for converting the filtered multiple analog signals into digital signals and returning them to the digital system.

[0007] In this application, a digital signal is transmitted to a first digital-to-analog converter (DAC), where it is converted into an analog signal. The parameters of an analog filter are adjusted using a multi-channel analog control voltage output from a timing control circuit. The analog signal is then filtered based on the parameter-adjusted analog filter, and the filtered analog signal is returned to the digital system via an analog-to-digital converter (ADC). This minimizes audio delay and achieves analog processing of digital signals within the digital system, as well as precise control of analog signals by the digital system. This solves the technical problem of existing digital synthesizers, which commonly use DSPs to implement digital filtering functions. This results in insufficient timbre reproduction due to limitations imposed by the discretization mechanism of digital signals, making it difficult to accurately reproduce the harmonic saturation characteristics and other physical characteristics that are difficult to digitally implement in analog filtering circuits. Furthermore, the timing control circuit in this solution reduces hardware complexity by using time-division multiplexing to output multi-channel analog control voltages, compared to traditional solutions that require multiple second DACs to operate in parallel, leading to higher costs and synchronization difficulties.

[0008] In one implementation of the first aspect, the timing control circuit module includes: a second digital-to-analog converter connected to the analog filter parameter control interface within the system, which converts the control signal output by the digital system into a multi-channel analog control voltage for controlling various parameters in the analog filter; and multiple analog switches, each connected to the second digital-to-analog converter, for turning on or off the output signal of the second digital-to-analog converter and a sample-and-hold circuit; the input ports of the sample-and-hold circuit are respectively connected to the multiple analog switches, and the output port of the sample-and-hold circuit is connected to the analog filter for stably outputting the analog control voltage to the analog filter.

[0009] In one implementation of the first aspect, the timing control circuit module further includes a chip select control interface: the chip select control interface is connected to a plurality of the analog switches and is used to control the analog switches to be connected or disconnected from the second digital-to-analog converter, so as to realize time-division multiplexing of the second digital-to-analog converter.

[0010] In one implementation of the first aspect, the system further includes: a temperature sensor for monitoring the temperature parameters of the analog filter and sending the temperature parameters to the main control unit of the digital system; the main control unit dynamically adjusts the analog control voltage output by the second digital-to-analog converter based on the temperature parameters, and compensates for the frequency shift caused by temperature drift of various parameters in the analog filter based on the adjusted analog control voltage.

[0011] In one implementation of the first aspect, the parameters within the analog filter include cutoff frequency, quality factor, and output voltage amplitude; the cutoff frequency, the quality factor, and the output voltage amplitude are controlled by a multi-channel analog control voltage.

[0012] In one implementation of the first aspect, the number of analog switches is at least one.

[0013] In one implementation of the first aspect, the second digital-to-analog converter includes at least one channel of analog control voltage.

[0014] In one implementation of the first aspect, the number of analog filters 140 is at least two.

[0015] As described above, the time-division multiplexing analog filtering system of this application has the following advantages:

[0016] 1) In this system, the digital signal is transmitted to the first digital-to-analog converter (DAC), where it is converted into an analog signal. The analog control voltage output by the timing control circuit adjusts the parameters of the analog filter, and the analog signal is then filtered based on the parameter-adjusted analog filter. The filtered analog signal is then returned to the digital system via the analog-to-digital converter (ADC), minimizing audio delay. This achieves the analog-to-analog processing of digital signals within the digital system and the precise control of analog signals by the digital system. It solves the technical problem that existing digital synthesizers generally use DSPs (Digital Signal Processors) to implement digital filtering functions, which are limited by the discretization mechanism of digital signals, making it difficult to accurately reproduce the unique harmonic saturation characteristics (i.e., the rich overtones introduced by nonlinear distortion) and other physical characteristics that are difficult to digitally implement, resulting in insufficient timbre reproduction.

[0017] 2) The timing control circuit outputs analog control voltage in a time-division multiplexing manner. Compared with the traditional solution which requires multiple second digital-to-analog converters to work in parallel, resulting in high cost and difficulty in synchronization, the timing control circuit in this solution reduces hardware complexity through time-division multiplexing.

[0018] 3) The timing control circuit module can complete 50 channels of analog control voltage output in real time, with high efficiency and low cost by using a single 8-channel second digital-to-analog converter and 6 analog switches.

[0019] 4) In this embodiment, a sample-and-hold circuit is built in the timing control circuit using capacitors and operational amplifiers. A low-noise operational amplifier is used as a buffer to maintain voltage stability during the switching interval of the second digital-to-analog converter output. This solves the technical problem in the prior art that the output analog control voltage is unstable due to the time-division multiplexing of the second digital-to-analog converter, making the output analog control voltage more stable.

[0020] 5) The timing control circuit module based on the chip select control interface provided in this application embodiment distributes the output of a single second digital-to-analog converter to multiple signal channels in a time-division manner through the timing control circuit, thereby achieving efficient utilization of hardware resources.

[0021] 6) The time-division multiplexing analog filtering system based on temperature sensors provided in this application embodiment solves the technical problem that analog filters are easily affected by ambient temperature, resulting in insufficient simulation depth of the analog filter for real analog timbre; compared with the traditional analog filter temperature drift compensation relying on passive component matching, which has limited accuracy; this application embodiment improves the stability of the analog signal after output filtering by active closed-loop calibration. Attached Figure Description

[0022] Figure 1 The diagram shown is a structural diagram of a time-division multiplexing analog filtering system provided in an embodiment of this application.

[0023] Figure 2 The diagram shown is a structural diagram of a timing control circuit module provided in an embodiment of this application.

[0024] Figure 3 The diagram shown is a structural diagram of a timing control circuit module based on a chip select control interface provided in an embodiment of this application.

[0025] Figure 4 The diagram shown illustrates the structure of a system for another time-division multiplexing analog filtering system provided in this application embodiment.

[0026] Figure 5 The diagram shown is a circuit diagram of a second digital-to-analog converter provided in an embodiment of this application.

[0027] Figure 6 The diagram shown is a circuit diagram of an analog switch provided in an embodiment of this application.

[0028] Figure 7 The diagram shown is a structural diagram of a sample-and-hold circuit provided in an embodiment of this application.

[0029] Component designation explanation

[0030] 100 Time-division multiplexing analog filtering system 133 Sample and hold circuit 110 Digital System 134 Chip select control interface 111 Main control unit 140 Analog Filter 120 First digital-to-analog converter 150 Analog-to-digital converter 130 Timing control circuit module 160 Temperature sensor 131 Second digital-to-analog converter 132 Analog switch Detailed Implementation

[0031] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0032] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. Therefore, the drawings only show the components related to this application and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0033] The technical solutions in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0034] like Figure 1 As shown in the figure, this application provides a structural diagram of a time-division multiplexing analog filtering system. Figure 1 As shown, the time-division multiplexing analog filtering system 100 provided in this application embodiment includes: a digital system 110, a first digital-to-analog converter 120, a timing control circuit module 130, an analog filter 140, and an analog-to-digital converter 150.

[0035] The digital system includes digital signals; a first digital-to-analog converter is connected to the digital system and is used to convert the digital signals into multiple analog signals; the input port of the timing control circuit module is connected to the digital system, and the output port of the timing control circuit module is connected to an analog filter, used to output multi-channel analog control voltage to the analog filter in a time-division manner to achieve more channels of output; the analog filter filters the multiple analog signals through the multi-channel analog control voltage; and the analog-to-digital converter is connected to the analog filter and is used to convert the filtered multiple analog signals into digital signals and return them to the digital system.

[0036] For example, the digital system is connected to the first digital-to-analog converter via a TDM interface and can output 16 channels of audio simultaneously.

[0037] Specifically, the analog-to-digital converter 150 is connected to the digital system 110 via a TDM interface, and can simultaneously send 16 channels of audio filtered by the analog filter 140 to the digital system 110.

[0038] It should be noted that the digital system is connected to the first digital-to-analog converter via a TDM interface, and can output audio with one channel, two channels, or any other suitable number of channels based on actual application requirements. This application does not limit the specific value of the audio output after the digital system and the first digital-to-analog converter are connected via a TDM interface.

[0039] In some embodiments, the number of analog filters 140 is at least two.

[0040] Specifically, the first digital-to-analog converter 120 can convert the digital signal output by the digital system 110 into 16 analog signals, and send the 16 analog signals to 16 analog filters 140 respectively.

[0041] In some embodiments, the parameters within the analog filter include cutoff frequency, output voltage amplitude, and quality factor; the cutoff frequency, output voltage amplitude, and quality factor are controlled by the multi-channel analog control voltage.

[0042] Specifically, each analog control voltage controls one parameter. If there are 16 analog filters in a time-division multiplexed analog filtering system, and each of the 16 analog filters includes 3 parameters, then a total of 48 analog control voltages are required.

[0043] For example, by controlling the cutoff frequency, output voltage amplitude, and quality factor of 16 analog filters 140 through 48 analog control voltages, the analog signals transmitted to the 16 analog filters 140 are filtered. The filtered 16 analog signals are then sent to the analog-to-digital converter 150, and after digital-to-analog conversion by the analog-to-digital converter 150, they are retransmitted to the digital system. This realizes the analog processing of digital signals located in the digital system, and solves the technical problem that existing digital synthesizers generally use DSPs (digital signal processors) to implement digital filtering functions. This is limited by the discretization processing mechanism of digital signals, making it difficult to accurately reproduce the harmonic saturation characteristics (i.e., the rich overtones introduced by nonlinear distortion) and other physical characteristics that are difficult to digitally realize, resulting in insufficient timbre reproduction.

[0044] It should be noted that the specific values ​​of the parameters in the multiple analog filters can be adjusted or not adjusted based on the specific temperature information, which will not be elaborated in this application.

[0045] It should be noted that, in this embodiment, the number of analog switches 132 is less than or equal to the number of channels of the second digital-to-analog converter 131, and to ensure that the adjustable analog voltages corresponding to all parameters in the analog filter can be modulated, the number of analog control voltages output by the second digital-to-analog converter 131 connected to the analog switches 132 must be greater than or equal to the total number of parameters in the analog filter. Under the constraints of the aforementioned numerical relationships among the analog switches, the second digital-to-analog converter, and the analog filter,

[0046] This application does not limit the specific values ​​of the number of analog filters and the number of analog signals listed in the embodiments. In practical applications, any appropriate number of analog filters and analog signals can be selected based on the specific application scenario, and this application does not impose any restrictions on this.

[0047] For example, if there is one analog switch, one channel in the second digital-to-analog converter, and two analog filters, the timing control circuit module outputs eight channels of analog voltage to the analog filters in a time-division multiplexing manner. Since each analog filter has three parameters, six adjustable analog voltages are required. The eight channels of analog voltage are greater than the six adjustable analog voltages, ensuring that the adjustable analog voltages corresponding to all parameters in the analog filters can be modulated. Therefore, the number of analog switches, the second digital-to-analog converter, and the analog filters meets the actual requirements.

[0048] Conversely, if there is one analog switch, one channel in the second digital-to-analog converter, and three analog filters, the timing control circuit module outputs eight channels of analog voltage to the analog filters in a time-division multiplexing manner. Since each analog filter has three parameters, nine adjustable analog voltages are required. If eight channels of analog voltage are less than nine adjustable analog voltages, then the number of analog switches, the second digital-to-analog converter, and the analog filters will prevent the modulation of the adjustable analog voltage corresponding to one of the parameters of the analog filters. Therefore, the number of analog switches, the second digital-to-analog converter, and the analog filters does not meet the actual requirements.

[0049] For example, the entire analog signal processing is embedded in the digital system, which can obtain the digital signal with lower latency after analog filtering from the analog-to-digital converter in real time.

[0050] This application provides a time-division multiplexing analog filtering system. In this system, a digital signal is transmitted to a first digital-to-analog converter (DAC), where it is converted into an analog signal. The analog control voltage output by a timing control circuit adjusts various parameters in the analog filter. Based on the parameter-adjusted analog filter, the analog signal is filtered, and the filtered analog signal is returned to the digital system via an analog-to-digital converter (ADC). This minimizes audio delay and achieves analog-to-analog processing of digital signals within the digital system, as well as precise control of analog signals by the digital system. It solves the technical problem that existing digital synthesizers commonly use DSPs (Digital Signal Processors) to implement digital filtering functions. This results in insufficient timbre reproduction due to limitations in the discretization mechanism of digital signals, making it difficult to accurately reproduce the unique harmonic saturation characteristics (i.e., rich overtones introduced by nonlinear distortion) and other physical characteristics that are difficult to digitally implement, leading to insufficient timbre reproduction. Furthermore, the timing control circuit outputs analog control voltage in a time-division multiplexing manner, which, compared to traditional solutions requiring multiple second DACs to operate in parallel, is costly and difficult to synchronize. The timing control circuit in this solution reduces hardware complexity through time-division multiplexing.

[0051] like Figure 2 As shown in the figure, this application provides a structural diagram of a timing control circuit module, as follows: Figure 2 As shown, the timing control circuit module 130 provided in this application embodiment includes: a second digital-to-analog converter 131, a plurality of analog switches 132, and a sample-and-hold circuit 133.

[0052] The second digital-to-analog converter 131 is connected to the analog filter parameter control interface in the system and is used to convert various parameters in the analog filter into multi-channel analog control voltages.

[0053] Multiple analog switches 132 are connected to the second digital-to-analog converter 131 respectively, and are used to turn the second digital-to-analog converter on or off.

[0054] The input ports of the sample-and-hold circuit are connected to the plurality of analog switches respectively, and the output port of the sample-and-hold circuit is connected to the analog filter, for stabilizing the output of the analog control voltage to the analog filter 140.

[0055] In some embodiments, the number of analog switches 132 is at least one.

[0056] Specifically, if the second digital-to-analog converter 131 can simultaneously output 8 channels of voltage signals, by using a time-division multiplexing approach, the 8-channel second digital-to-analog converter 131, combined with 6 analog switches 132 for expansion, can form 8*6+2=50 channels of analog control voltage output. Among them, 48 channels of analog control voltage are used to control the parameters in the analog filter, and the other two channels of analog control voltage are used for other voltage control.

[0057] The timing control circuit module provided in this application can complete 50 channels of analog control voltage output in real time, efficiently and at low cost using a single 8-channel second digital-to-analog converter and 6 analog switches 132. A sample-and-hold circuit 133 is built in the timing control circuit 130 using capacitors and operational amplifiers, and a low-noise operational amplifier is used as a buffer to maintain voltage stability during the output switching interval of the second digital-to-analog converter. This solves the technical problem in the prior art that the time-division multiplexing of the second digital-to-analog converter 131 causes unstable output analog control voltage, making the output analog control voltage more stable.

[0058] like Figure 3 As shown in the figure, this application provides a structural diagram of a timing control circuit module based on a chip select control interface. Figure 3 As shown, the timing control circuit module 130 also includes a chip select control interface 134.

[0059] One end of the chip select control interface 134 is located on the digital system 110.

[0060] The chip select control interface is connected to multiple analog switches and is used to control the analog switches to be connected or disconnected from the second digital-to-analog converter, so as to realize the time-division multiplexing of the second digital-to-analog converter.

[0061] Specifically, the input interface of the second digital-to-analog converter 131 in the timing control circuit module 130 is connected to the digital system 110 through a serial peripheral interface (SPI).

[0062] Specifically, by adjusting the SPI refresh rate and the size of the sampling capacitor in the sample-and-hold circuit 133, the real-time performance and stability of the output analog control voltage can be precisely controlled.

[0063] The timing control circuit module based on the chip select control interface provided in this application embodiment distributes the output of a single second digital-to-analog converter to multiple signal channels in a time-division manner through the timing control circuit, thereby achieving efficient utilization of hardware resources.

[0064] like Figure 4 As shown in the figure, this application provides a structural diagram of another time-division multiplexing analog filtering system, as follows: Figure 4As shown, another time-division multiplexing analog filtering system includes a temperature sensor 160 and a main control unit 111.

[0065] The temperature sensor 160 is used to monitor the temperature parameters of the analog filter 140 and send the temperature parameters to the main control unit 111 of the digital system 110. The main control unit 111 dynamically adjusts the analog control voltage output by the second digital-to-analog converter 131 based on the temperature parameters, and compensates for the frequency deviation caused by the drift of various temperature parameters in the analog filter 140 based on the adjusted analog control voltage.

[0066] The main control unit 111 includes a calibration algorithm.

[0067] Specifically, the temperature sensor 160 can collect temperature parameters of multiple analog filters 140 in real time and send the collected temperature parameters to the main control unit 111 through the I²C interface. The calibration algorithm in the main control unit 111 dynamically adjusts the analog control voltage output by the second digital-to-analog converter based on the temperature parameters, and compensates for the frequency shift caused by temperature drift of various parameters in the analog filter based on the adjusted analog control voltage.

[0068] For example, if a more accurate pitch is required, the main control unit can perform automatic calibration and send the calibrated analog control voltage to the analog filter through a timing control circuit.

[0069] For example, if a temperature sensor detects a temperature of 20 degrees Celsius for a certain analog filter, and the analog control voltage is 1V, the corresponding output frequency of the analog filter is 1kHz. When the temperature sensor detects a temperature of 25 degrees Celsius for the analog filter, the analog control voltage needs to be calibrated and adjusted to 1.1V for the analog filter to output a 1kHz frequency.

[0070] The time-division multiplexing analog filtering system based on a temperature sensor provided in this application solves the technical problem that analog filters are easily affected by ambient temperature, resulting in insufficient simulation depth of the real analog timbre. Compared with the traditional analog filter's 140°C temperature drift compensation which relies on passive component matching and has limited accuracy, this application improves the stability of the analog signal output after filtering by active closed-loop calibration.

[0071] like Figure 5 As shown in the figure, this application embodiment provides a circuit diagram of a second digital-to-analog converter.

[0072] like Figure 6 As shown, this application provides a circuit diagram of an analog switch.

[0073] In some embodiments, the number of analog switches is at least one, and the one analog switch selects channels through the control of ABC and D8_INH to achieve the effect of time-division multiplexing.

[0074] like Figure 7 As shown in the figure, this application provides a structural diagram of a sample-and-hold circuit.

[0075] C432 represents the sample-and-hold capacitor, U59-B represents the voltage follower (which isolates the preceding and following stages through impedance transformation), and VCA2_IN represents the output to the filter parameter control pin.

[0076] In the embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, or methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of modules / units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or units may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection of apparatuses or modules or units may be electrical, mechanical, or other forms.

[0077] The modules / units described as separate components may or may not be physically separate. The components shown as modules / units may or may not be physical modules; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules / units can be selected to achieve the objectives of the embodiments of this application, depending on actual needs. For example, the functional modules / units in the various embodiments of this application may be integrated into one processing module, or each module / unit may exist physically separately, or two or more modules / units may be integrated into one module / unit.

[0078] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0079] The descriptions of the processes or structures corresponding to the above figures each have their own emphasis. For parts of a process or structure that are not described in detail, please refer to the relevant descriptions of other processes or structures.

[0080] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. A time-division multiplexing analog filtering system, characterized in that, The system includes: A digital system, wherein the digital system includes digital signals; A first digital-to-analog converter, connected to the digital system, is used to convert the digital signal into multiple analog signals; A timing control circuit module, wherein the input port of the timing control circuit module is connected to the digital system and the output port of the timing control circuit module is connected to the analog filter, for time-division multiplexing of the analog filter to output multi-channel analog control voltage, thereby achieving more channels of output; An analog filter is used to filter the multiple analog signals through a multi-channel analog control voltage. An analog-to-digital converter, connected to the analog filter, is used to convert the filtered multi-channel analog signals into digital signals and return them to the digital system.

2. The system according to claim 1, characterized in that, The timing control circuit module includes: The second digital-to-analog converter is connected to the analog filter parameter control interface in the system, and converts the control signal output by the digital system into a multi-channel analog control voltage for controlling various parameters in the analog filter. Multiple analog switches are connected to the second digital-to-analog converter respectively, and are used to turn on or off the output signal and sample-and-hold circuit of the second digital-to-analog converter; The input ports of the sample-and-hold circuit are connected to the plurality of analog switches respectively, and the output port of the sample-and-hold circuit is connected to the analog filter for stabilizing the output of the analog control voltage to the analog filter.

3. The system according to claim 2, characterized in that, The timing control circuit module also includes a chip select control interface: The chip select control interface is connected to multiple analog switches and is used to control the analog switches to be connected or disconnected from the second digital-to-analog converter, so as to realize the time-division multiplexing of the second digital-to-analog converter.

4. The system according to claim 1, characterized in that, The system also includes: A temperature sensor is used to monitor the temperature parameters of the analog filter and send the temperature parameters to the main control unit of the digital system; The main control unit dynamically adjusts the analog control voltage output by the second digital-to-analog converter based on the temperature parameter, and compensates for the frequency shift caused by temperature drift of various parameters in the analog filter based on the adjusted analog control voltage.

5. The system according to claim 2, characterized in that, The parameters within the analog filter include cutoff frequency, quality factor, and output voltage amplitude; the cutoff frequency, quality factor, and output voltage amplitude are controlled by a multi-channel analog control voltage.

6. The system according to claim 2, characterized in that, The number of analog switches is at least one.

7. The system according to claim 2, characterized in that, The second digital-to-analog converter includes at least one channel of analog control voltage output.

8. The system according to claim 1, characterized in that, The number of analog filters is at least two.

Images