Analog-to-digital conversion circuit introducing white noise

By introducing white noise processing technology into the analog-to-digital conversion circuit, the problem of insufficient spurious dynamic range of the ADC chip is solved, which improves signal conversion capabilities and system performance, and reduces costs.

CN223194695UActive Publication Date: 2025-08-05CHONGQING HUILING ELECTRONIC NEW TECH CO LTD
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Patent Information

Application Number
CN202422473337.6
Authority / Receiving Office
CN · China
Patent Type
Utility models(China)
Current Assignee / Owner
Filing Date
2024-10-14
Publication Date
2025-08-05
Estimated Expiration
2034-10-14

AI Technical Summary

Technical Problem

The spurious-free dynamic range indicators of existing ADC chips cannot meet some high-demand circuit design requirements, resulting in signal distortion during analog signals.

Method used

An analog-to-digital conversion circuit with white noise is introduced. The useful analog signal and added noise signals are combined through the combined circuit module, and an out-of-band noise signal is generated through the noise source module. The amplification filter module is used to adjust the amplification signal amplitude, and the analog-to-digital conversion is completed through the ADC chip. Finally, the out-of-band noise is filtered out in the digital processor to obtain a useful digital signal.

Benefits of technology

It improves the ability of integrated ADC chip to convert small signals, improves the system's spurious dynamic range index by about 8dB, saving the cost of purchasing high-performance ADC chips.

✦ Generated by Eureka AI based on patent content.

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Abstract

An analog-to-digital conversion circuit introducing white noise is characterized in that a combining module is arranged, the first input end of the combining module obtains analog signals, the second input end of the combining module is connected with an amplifying and filtering module, and the input end of the amplifying and filtering module is connected with a noise source module; the output end group of the combining module is connected with a digital filtering module through an analog-to-digital converter (ADC), and the digital filtering module outputs a digital signal; a first input end of the combining module is connected with a positive end of a pre-stage winding of the mutual inductor T1 after acquiring an analog signal, and a second input end of the combining module is connected with the positive end of the pre-stage winding of the mutual inductor T1 through a high-pass filter after acquiring a noise signal from the amplifying and filtering circuit; the positive end of the post-stage winding of the mutual inductor T1 is connected with the first input end of the ADC through a resistor R3, and the negative end of the post-stage winding of the mutual inductor T1 is connected with the second input end of the ADC through a resistor R2. The method has the advantages that the small signal conversion capacity of the integrated ADC chip is improved, and the spurious-free dynamic range index of the system is improved; a high-performance ADC chip does not need to be purchased, so that the cost is saved.
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Description

Technical Field

[0001] The utility model relates to the technical field of analog-to-digital converters, in particular to an analog-to-digital conversion circuit introducing white noise. Background Art

[0002] Analog signal digitization is currently typically achieved using integrated ADC chips (analog-to-digital conversion). The sampling and holding circuit will cause distortion of the original signal. The spurious-free dynamic range indicator measures the difference between noise and useful signals. The spurious-free dynamic range is an important indicator of the ADC chip and restricts the back-end digital signal processing and application.

[0003] The spurious-free dynamic range index of existing ADC chips cannot meet some high-demand circuit design requirements. Utility Model Content

[0004] The utility model provides an analog-to-digital conversion circuit that introduces white noise, which can improve the small signal conversion capability of the integrated ADC chip and enhance the spurious-free dynamic range index of the system.

[0005] To achieve the above-mentioned object, the present invention provides an analog-to-digital conversion circuit for introducing white noise, the key of which is: a combining module is provided, a first input end of the combining module obtains an analog signal, a second input end of the combining module is connected to an amplifying and filtering module, and an input end of the amplifying and filtering module is connected to a noise source module; an output end group of the combining module is connected to a digital filtering module via an analog-to-digital converter ADC, and the digital filtering module outputs a digital signal;

[0006] The first input end of the combining module obtains the analog signal and is then connected to the positive end of the front winding of the transformer T1. The first input end is also connected in series with a resistor R1 and then grounded. The second input end of the combining module obtains the noise signal from the amplifying and filtering circuit and is then connected to the positive end of the front winding of the transformer T1 through a high-pass filter. The negative end of the front winding of the transformer T1 is grounded.

[0007] The positive end of the rear winding of the transformer T1 is connected to the front end of the resistor R3, the rear end of the resistor R3 is connected to the first input end of the analog-to-digital converter ADC, and the rear end of the resistor R3 is connected in series with a capacitor C5 and then grounded;

[0008] The negative end of the rear winding of the transformer T1 is connected to the front end of the resistor R2, the rear end of the resistor R2 is connected to the second input end of the analog-to-digital converter ADC, and the rear end of the resistor R2 is connected in series with a capacitor C4 and then grounded;

[0009] A capacitor C3 is connected in series between the rear ends of the resistors R2 and R3.

[0010] The combiner module combines the useful analog signal and the added noise signal. The noise input of the combiner module uses a high-pass filter. The useful signal is directly matched to the input, achieving impedance matching across the entire frequency band. This adds the signal voltages and merges the two signals. The signals are then converted to differential signals via a transformer and output to a subsequent ADC chip for digital conversion.

[0011] The above design uses a noise source module to generate an out-of-band noise signal. The analog amplifier (or amplifier circuit) in the amplification and filtering module adjusts the noise signal's amplitude. The analog filter (or filtering unit) removes the in-band noise signal to prevent interference with the useful analog signal. The processed noise signal is then added to the useful analog signal through a combiner module. The ADC chip then performs analog-to-digital conversion to produce a digital signal. The digital processor then filters out the out-of-band noise signal through a digital filtering module, ultimately producing a useful digital signal.

[0012] It has been verified that by adding a noise signal for analog-to-digital conversion, the spurious-free dynamic range indicator can be improved by about 8dB based on the performance of the original ADC chip.

[0013] Preferably, the noise source module is provided with a digital-to-analog converter DAC and a digital noise filter. The digital noise filter acquires digital noise. The digital noise filter digitally filters the digital noise, converts the digital noise into analog noise through the digital-to-analog converter DAC, and sends the digital noise to the amplification and filtering module.

[0014] The noise source module is mainly implemented using a DAC chip, which generates full-band random white noise at the digital end, and the generating polynomial is x24+x7+x2+x+1; after passing through a digital noise filter, the noise signal near half the sampling rate is retained.

[0015] The noise source module completes the generation of the noise source. The useful signal is around one-quarter of the sampling rate, and the added noise is around one-half the sampling rate. They are distinguished in the frequency domain without affecting the digital conversion of the useful analog signal.

[0016] Preferably, the amplifying and filtering module is provided with an amplifying circuit and a filtering circuit, the input end of the amplifying circuit is connected to the noise source module, and the output end of the amplifying circuit is connected to the second input end of the combining module via the filtering circuit.

[0017] The amplification and filtering module is used to complete the power amplification of the white noise signal, so that the output signal power is within an appropriate range, and at the same time filter out the noise signal within the useful signal frequency band.

[0018] The amplification and filtering module uses amplifier components and resistors, capacitors and inductors to complete signal amplification and filtering processing.

[0019] Preferably, the amplifying circuit is provided with a first amplifying unit, a low-pass filter and a second amplifying unit in sequence;

[0020] The first amplifying unit is provided with a first amplifier U1, an input terminal of the first amplifier U1 is connected in series with a capacitor C6 and then connected to the noise source module, and an output terminal of the first amplifier U1 is connected in series with a capacitor C9 and then connected to the low-pass filter;

[0021] The bias power supply terminal of the first amplifier U1 is connected in series with a resistor R4 and then connected to a 3.3V power supply. The bias power supply terminal is also connected in series with an inductor L2 and then connected to the input terminal of the first amplifier U1. The output terminal of the first amplifier U1 is connected in series with an inductor L3 and a resistor R5 in sequence and then connected to a 3.3V power supply.

[0022] The low-pass filter is provided with an inductor L4, the front end of the inductor L4 is connected to the first amplifying unit, the front end of the inductor L4 is further connected in series with a capacitor C10 and then grounded, the rear end of the inductor L4 is connected to the second amplifying unit, the rear end of the inductor L4 is further connected in series with a capacitor C11 and then grounded;

[0023] The second amplifying unit is provided with a second amplifier U2, an input terminal of the second amplifier U2 is connected in series with a capacitor C12 and then connected to the low-pass filter, and an output terminal of the second amplifier U2 is connected in series with a capacitor C15 and then connected to the filter circuit;

[0024] The bias power supply terminal of the second amplifier U2 is connected in series with a resistor R6 and then connected to a 3.3V power supply. The bias power supply terminal bias is also connected in series with an inductor L5 and then connected to the input terminal of the second amplifier U2; the output terminal of the second amplifier U2 is connected in series with an inductor L6 and a resistor R7 in sequence and then connected to a 3.3V power supply.

[0025] Preferably, the filtering circuit is a 7th-order bandpass filter;

[0026] The filter circuit is provided with a capacitor C16, the front end of the capacitor C16 is connected to the amplifier circuit, the rear end of the capacitor C16 is connected in series with a capacitor C20 and an inductor L8, and then connected to the front end of the inductor C9, the rear end of the capacitor C16 is further connected in series with an inductor L7 and then grounded, the rear end of the capacitor C16 is further connected in series with a capacitor C17 and then grounded, and the rear end of the capacitor C16 is further connected in series with a capacitor C18 and then grounded; the two ends of the capacitor C20 are connected in parallel with a capacitor C19, and the two ends of the capacitor C20 are further connected in parallel with a capacitor C21;

[0027] The rear end of the inductor L9 is connected in series with the capacitor C25 and the inductor L11, and then connected to the front end of the inductor L12. The rear end of the inductor L9 is also connected in series with the inductor L10 and then grounded. The rear end of the inductor L9 is also connected in series with the capacitor C22 and then grounded. The rear end of the inductor L9 is also connected in series with the capacitor C23 and then grounded. The two ends of the capacitor C25 are connected in parallel with a capacitor C24.

[0028] The rear end of the inductor L12 is connected in series with the capacitor C29 and the inductor L14, and then connected to the front end of the inductor L15. The rear end of the inductor L12 is also connected in series with the inductor L13 and then grounded. The rear end of the inductor L12 is also connected in series with the capacitor C26 and then grounded. The rear end of the inductor L12 is also connected in series with the capacitor C27 and then grounded. The two ends of the capacitor C29 are connected in parallel with a capacitor C28, and the two ends of the capacitor C29 are also connected in parallel with a capacitor C30.

[0029] The rear end of the inductor L15 is connected in series with a capacitor C33 and then connected to the combiner module. The rear end of the inductor L15 is also connected in series with an inductor L16 and then grounded. The rear end of the inductor L15 is also connected in series with a capacitor C31 and then grounded. The rear end of the inductor L15 is also connected in series with a capacitor C32 and then grounded.

[0030] Preferably, the high-pass filter is provided with a capacitor C1, a capacitor C2 and an inductor L1; the second input end of the combiner module is connected in series with the capacitors C1 and C2 in sequence and then connected to the positive input end of the transformer T1; the common end of the capacitors C1 and C2 is connected in series with the inductor L1 and then grounded.

[0031] Preferably, the digital filtering module is a low-pass digital filter.

[0032] The digital filter module is used to retain useful signals and filter out-of-band noise signals. The digital filter module is installed in a programmable logic device and is a low-pass digital filter added before digital signal processing. The purpose is to filter the added noise signal and restore the useful signal.

[0033] The beneficial effects of the present invention are as follows: not only the small signal conversion capability of the integrated ADC chip is improved, but also the spurious-free dynamic range index of the system is improved; by adding an optimized circuit on the basis of the existing circuit, there is no need to purchase a high-performance ADC chip, thus saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural block diagram of the utility model;

[0035] Figure 2 This is the circuit schematic diagram of the combiner module;

[0036] Figure 3 This is the schematic diagram of the amplification circuit in the amplification and filtering module;

[0037] Figure 4 This is the schematic diagram of the filter circuit in the amplified filter module;

[0038] Figure 5 This is the amplitude-frequency characteristic diagram of the digital noise filter in the noise source module;

[0039] Figure 6 This is the amplitude-frequency characteristic diagram of the digital filtering module. DETAILED DESCRIPTION

[0040] The present invention will be further described in detail below with reference to the accompanying drawings and specific examples. The following examples or drawings are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0041] like Figure 1 As shown: An analog-to-digital conversion circuit that introduces white noise is provided with a combining module, the first input end of the combining module obtains an analog signal, the second input end of the combining module is connected to an amplifying and filtering module, and the input end of the amplifying and filtering module is connected to a noise source module; the output end group of the combining module is connected to a digital filtering module via an analog-to-digital converter ADC, and the digital filtering module outputs a digital signal.

[0042] like Figure 2 As shown: the first input end of the combining module obtains the analog signal and is connected to the positive end of the front winding of the mutual inductor T1. The first input end is also connected in series with a resistor R1 and then grounded. The second input end of the combining module obtains the noise signal from the amplifying and filtering circuit, and then is connected to the positive end of the front winding of the mutual inductor T1 through a high-pass filter. The negative end of the front winding of the mutual inductor T1 is grounded.

[0043] The positive end of the rear winding of the transformer T1 is connected to the front end of the resistor R3, the rear end of the resistor R3 is connected to the first input end of the analog-to-digital converter ADC, and the rear end of the resistor R3 is connected in series with a capacitor C5 and then grounded;

[0044] The negative end of the rear winding of the transformer T1 is connected to the front end of the resistor R2, the rear end of the resistor R2 is connected to the second input end of the analog-to-digital converter ADC, and the rear end of the resistor R2 is connected in series with a capacitor C4 and then grounded;

[0045] A capacitor C3 is connected in series between the rear ends of the resistors R2 and R3.

[0046] The high-pass filter is provided with capacitor C1, capacitor C2 and inductor L1. The second input end of the combining module is connected in series with capacitors C1 and C2 in sequence and then connected to the positive input end of the transformer T1. The common end of the capacitors C1 and C2 is connected in series with inductor L1 and then grounded.

[0047] The combining module combines the useful signal and the added noise signal.

[0048] The noise input part of the combiner module adopts a high-pass filter, and the useful signal is directly matched to the input to achieve full-band impedance matching, complete the addition of signal voltage, and realize the merging of two signals. The signal is then converted into a differential signal through a transformer and output to the subsequent ADC chip for digital conversion.

[0049] like Figure 1As shown: the noise source module is provided with a digital-to-analog converter DAC and a digital noise filter. The digital noise filter obtains digital noise. The digital noise filter digitally filters the digital noise, converts it into analog noise through the digital-to-analog converter DAC, and sends it to the amplification and filtering module.

[0050] The noise source module is mainly implemented by DAC chip, generating full-band random white noise at the digital end, and the generating polynomial is x24+x7+x2+x+1; after passing through the digital noise filter, the noise signal near half the sampling rate is retained, and the digital noise filter is designed as follows Figure 5 shown.

[0051] The noise source module completes the generation of the noise source. The useful signal is around one-quarter of the sampling rate, and the added noise is around one-half the sampling rate. They are distinguished in the frequency domain without affecting the digital conversion of the useful signal.

[0052] like Figure 3 、 Figure 4 As shown: the amplifying and filtering module is provided with an amplifying circuit and a filtering circuit, the input end of the amplifying circuit is connected to the noise source module, and the output end of the amplifying circuit is connected to the second input end of the combining module via the filtering circuit.

[0053] The amplification and filtering module completes the power amplification of the white noise signal, so that the output signal power is within an appropriate range, and at the same time filters out the noise signal within the useful signal frequency band.

[0054] like Figure 3 As shown: the amplifying circuit is provided with a first amplifying unit, a low-pass filter and a second amplifying unit in sequence;

[0055] The first amplifying unit is provided with a first amplifier U1, an input terminal of the first amplifier U1 is connected in series with a capacitor C6 and then connected to the noise source module, and an output terminal of the first amplifier U1 is connected in series with a capacitor C9 and then connected to the low-pass filter;

[0056] The bias power supply terminal of the first amplifier U1 is connected in series with a resistor R4 and then connected to a 3.3V power supply. The bias power supply terminal is also connected in series with an inductor L2 and then connected to the input terminal of the first amplifier U1. The output terminal of the first amplifier U1 is connected in series with an inductor L3 and a resistor R5 in sequence and then connected to a 3.3V power supply.

[0057] The low-pass filter is provided with an inductor L4, the front end of the inductor L4 is connected to the first amplifying unit, the front end of the inductor L4 is further connected in series with a capacitor C10 and then grounded, the rear end of the inductor L4 is connected to the second amplifying unit, the rear end of the inductor L4 is further connected in series with a capacitor C11 and then grounded;

[0058] The second amplifying unit is provided with a second amplifier U2, an input terminal of the second amplifier U2 is connected in series with a capacitor C12 and then connected to the low-pass filter, and an output terminal of the second amplifier U2 is connected in series with a capacitor C15 and then connected to the filter circuit;

[0059] The bias power supply terminal of the second amplifier U2 is connected in series with a resistor R6 and then connected to a 3.3V power supply. The bias power supply terminal bias is also connected in series with an inductor L5 and then connected to the input terminal of the second amplifier U2; the output terminal of the second amplifier U2 is connected in series with an inductor L6 and a resistor R7 in sequence and then connected to a 3.3V power supply.

[0060] like Figure 4 As shown: the filtering circuit is a 7th-order bandpass filter;

[0061] The filter circuit is provided with a capacitor C16, the front end of the capacitor C16 is connected to the amplifier circuit, the rear end of the capacitor C16 is connected in series with a capacitor C20 and an inductor L8, and then connected to the front end of the inductor C9, the rear end of the capacitor C16 is further connected in series with an inductor L7 and then grounded, the rear end of the capacitor C16 is further connected in series with a capacitor C17 and then grounded, and the rear end of the capacitor C16 is further connected in series with a capacitor C18 and then grounded; the two ends of the capacitor C20 are connected in parallel with a capacitor C19, and the two ends of the capacitor C20 are further connected in parallel with a capacitor C21;

[0062] The rear end of the inductor L9 is connected in series with the capacitor C25 and the inductor L11, and then connected to the front end of the inductor L12. The rear end of the inductor L9 is also connected in series with the inductor L10 and then grounded. The rear end of the inductor L9 is also connected in series with the capacitor C22 and then grounded. The rear end of the inductor L9 is also connected in series with the capacitor C23 and then grounded. The two ends of the capacitor C25 are connected in parallel with a capacitor C24.

[0063] The rear end of the inductor L12 is connected in series with the capacitor C29 and the inductor L14, and then connected to the front end of the inductor L15. The rear end of the inductor L12 is also connected in series with the inductor L13 and then grounded. The rear end of the inductor L12 is also connected in series with the capacitor C26 and then grounded. The rear end of the inductor L12 is also connected in series with the capacitor C27 and then grounded. The two ends of the capacitor C29 are connected in parallel with a capacitor C28, and the two ends of the capacitor C29 are also connected in parallel with a capacitor C30.

[0064] The rear end of the inductor L15 is connected in series with a capacitor C33 and then connected to the combiner module. The rear end of the inductor L15 is also connected in series with an inductor L16 and then grounded. The rear end of the inductor L15 is also connected in series with a capacitor C31 and then grounded. The rear end of the inductor L15 is also connected in series with a capacitor C32 and then grounded.

[0065] The digital filter module is a low-pass digital filter. The digital filter module retains the useful signal and filters the out-of-band noise signal. Its amplitude-frequency characteristics refer to Figure 6The digital filter module is installed in the programmable logic device and is a low-pass digital filter added before digital signal processing. Its purpose is to filter the added noise signal and restore the useful signal.

[0066] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An analog-to-digital conversion circuit that introduces white noise, characterized in that: A combining module is provided, wherein a first input end of the combining module obtains an analog signal, a second input end of the combining module is connected to an amplifying and filtering module, and an input end of the amplifying and filtering module is connected to a noise source module; an output end group of the combining module is connected to a digital filtering module via an analog-to-digital converter ADC, and the digital filtering module outputs a digital signal; The first input end of the combining module obtains the analog signal and is then connected to the positive end of the front winding of the transformer T1. The first input end is also connected in series with a resistor R1 and then grounded. The second input end of the combining module obtains the noise signal from the amplifying and filtering circuit and is then connected to the positive end of the front winding of the transformer T1 through a high-pass filter. The negative end of the front winding of the transformer T1 is grounded. The positive end of the rear winding of the transformer T1 is connected to the front end of the resistor R3, the rear end of the resistor R3 is connected to the first input end of the analog-to-digital converter ADC, and the rear end of the resistor R3 is connected in series with a capacitor C5 and then grounded; The negative end of the rear winding of the transformer T1 is connected to the front end of the resistor R2, the rear end of the resistor R2 is connected to the second input end of the analog-to-digital converter ADC, and the rear end of the resistor R2 is connected in series with a capacitor C4 and then grounded; A capacitor C3 is connected in series between the rear ends of the resistors R2 and R3.

2. The analog-to-digital conversion circuit for introducing white noise according to claim 1, wherein: The noise source module is provided with a digital-to-analog converter DAC and a digital noise filter. The digital noise filter obtains digital noise, and after the digital noise filter digitally filters the digital noise, it is converted into analog noise through the digital-to-analog converter DAC and sent to the amplification and filtering module.

3. The analog-to-digital conversion circuit for introducing white noise according to claim 1, wherein: The amplifying and filtering module is provided with an amplifying circuit and a filtering circuit. The input end of the amplifying circuit is connected to the noise source module, and the output end of the amplifying circuit is connected to the second input end of the combining module via the filtering circuit.

4. The analog-to-digital conversion circuit with white noise introduction according to claim 3, wherein: The amplifying circuit is provided with a first amplifying unit, a low-pass filter and a second amplifying unit in sequence; The first amplifying unit is provided with a first amplifier U1, an input terminal of the first amplifier U1 is connected in series with a capacitor C6 and then connected to the noise source module, and an output terminal of the first amplifier U1 is connected in series with a capacitor C9 and then connected to the low-pass filter; The bias power supply terminal of the first amplifier U1 is connected in series with a resistor R4 and then connected to a 3.3V power supply. The bias power supply terminal is also connected in series with an inductor L2 and then connected to the input terminal of the first amplifier U1. The output terminal of the first amplifier U1 is connected in series with an inductor L3 and a resistor R5 in sequence and then connected to a 3.3V power supply. The low-pass filter is provided with an inductor L4, the front end of the inductor L4 is connected to the first amplifying unit, the front end of the inductor L4 is further connected in series with a capacitor C10 and then grounded, the rear end of the inductor L4 is connected to the second amplifying unit, the rear end of the inductor L4 is further connected in series with a capacitor C11 and then grounded; The second amplifying unit is provided with a second amplifier U2, an input terminal of the second amplifier U2 is connected in series with a capacitor C12 and then connected to the low-pass filter, and an output terminal of the second amplifier U2 is connected in series with a capacitor C15 and then connected to the filter circuit; The bias power supply terminal of the second amplifier U2 is connected in series with a resistor R6 and then connected to a 3.3V power supply. The bias power supply terminal bias is also connected in series with an inductor L5 and then connected to the input terminal of the second amplifier U2; the output terminal of the second amplifier U2 is connected in series with an inductor L6 and a resistor R7 in sequence and then connected to a 3.3V power supply.

5. The analog-to-digital conversion circuit for introducing white noise according to claim 3, wherein: The filtering circuit is a 7th-order bandpass filter; The filter circuit is provided with a capacitor C16, the front end of the capacitor C16 is connected to the amplifier circuit, the rear end of the capacitor C16 is connected in series with a capacitor C20 and an inductor L8, and then connected to the front end of the inductor C9, the rear end of the capacitor C16 is further connected in series with an inductor L7 and then grounded, the rear end of the capacitor C16 is further connected in series with a capacitor C17 and then grounded, and the rear end of the capacitor C16 is further connected in series with a capacitor C18 and then grounded; the two ends of the capacitor C20 are connected in parallel with a capacitor C19, and the two ends of the capacitor C20 are further connected in parallel with a capacitor C21; The rear end of the inductor L9 is connected in series with the capacitor C25 and the inductor L11, and then connected to the front end of the inductor L12. The rear end of the inductor L9 is also connected in series with the inductor L10 and then grounded. The rear end of the inductor L9 is also connected in series with the capacitor C22 and then grounded. The rear end of the inductor L9 is also connected in series with the capacitor C23 and then grounded. The two ends of the capacitor C25 are connected in parallel with a capacitor C24. The rear end of the inductor L12 is connected in series with the capacitor C29 and the inductor L14, and then connected to the front end of the inductor L15. The rear end of the inductor L12 is also connected in series with the inductor L13 and then grounded. The rear end of the inductor L12 is also connected in series with the capacitor C26 and then grounded. The rear end of the inductor L12 is also connected in series with the capacitor C27 and then grounded. The two ends of the capacitor C29 are connected in parallel with a capacitor C28, and the two ends of the capacitor C29 are also connected in parallel with a capacitor C30. The rear end of the inductor L15 is connected in series with a capacitor C33 and then connected to the combiner module. The rear end of the inductor L15 is also connected in series with an inductor L16 and then grounded. The rear end of the inductor L15 is also connected in series with a capacitor C31 and then grounded. The rear end of the inductor L15 is also connected in series with a capacitor C32 and then grounded.

6. The analog-to-digital conversion circuit for introducing white noise according to claim 1, wherein: The high-pass filter is provided with capacitor C1, capacitor C2 and inductor L1. The second input end of the combining module is connected in series with capacitors C1 and C2 in sequence and then connected to the positive input end of the transformer T1. The common end of the capacitors C1 and C2 is connected in series with inductor L1 and then grounded.

7. The analog-to-digital conversion circuit with white noise introduction according to claim 1, wherein: The digital filtering module is a low-pass digital filter.