Sampling circuit with high precision and strong anti-interference performance
By introducing a permalloy sensor, EMC devices, and multiple filtering circuits into the sampling circuit, combined with a low-temperature drift reference voltage source, the problems of noise suppression and temperature drift in traditional sampling circuits in high-interference environments are solved, achieving high-precision and stable signal sampling.
Patent Information
- Application Number
- CN202520312518.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-26
- Publication Date
- 2026-02-24
- Estimated Expiration
- 2035-02-26
AI Technical Summary
Traditional sampling circuits cannot effectively suppress noise in high-interference environments, and temperature changes cause reference voltage drift, affecting the accuracy of analog-to-digital converters. Existing technologies are complex and costly, making them difficult to widely adopt.
A high-input-impedance permalloy sensor, EMC devices, isolation voltage transformers, and multiple filtering circuits are used, combined with a low-temperature drift reference voltage source, to construct an anti-interference circuit, including a varistor, TVS diode, filter capacitor, current-limiting resistor, ferrite bead, and RC filter circuit, to eliminate common-mode voltage drift and noise interference.
It significantly improves the anti-interference capability and accuracy of the sampling circuit, ensures signal stability, adapts to high-precision sampling in complex environments, reduces temperature-induced errors, and improves system reliability.
Smart Images
Figure CN223942695U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of signal sampling technology, and in particular to a high-precision sampling circuit with strong anti-interference capabilities. Background Technology
[0002] In signal processing systems, precision measurement technology, and integrated circuit design, the accuracy and stability of signal sampling have always been critical issues of great concern. Traditional sampling circuits often fail to effectively suppress noise in high-interference environments, especially when small signal sampling accuracy is low and susceptible to interference leading to sampling errors. Simultaneously, temperature variations can cause drift in the reference voltage, affecting the accuracy of the analog-to-digital converter (ADC). To address these issues, existing technologies typically improve sampling system performance by adding complex anti-interference circuits and temperature compensation mechanisms. However, these methods are often costly and complex to implement, hindering widespread adoption in practical applications. Therefore, how to simplify circuit design and improve anti-interference capabilities while ensuring high-precision sampling has become an important research direction for the development of signal sampling technology. Utility Model Content
[0003] To overcome the shortcomings of the existing technology, the technical problem to be solved by this utility model is to propose a high-precision sampling circuit with strong anti-interference capabilities, and the following technical solution is adopted:
[0004] A high-precision, strong anti-interference sampling circuit includes a sensor module, the output signal of which is transmitted to a digital signal processing unit via a sampling chip, and an anti-interference circuit is provided between the sensor module and the sampling chip.
[0005] The aforementioned anti-interference circuit includes EMC devices, an isolation voltage transformer, and multiple filter circuits connected in sequence.
[0006] The aforementioned isolation voltage transformer is encapsulated in permalloy.
[0007] As a further improvement, the aforementioned sensor module includes one or more permalloy type sensors that output AC analog signals.
[0008] As a further improvement, the aforementioned EMC device is a varistor connected in parallel between the positive signal input terminal and the negative signal input terminal of the aforementioned anti-interference circuit.
[0009] As a further improvement, the current-carrying capacity of the above-mentioned varistor is not less than 3.5kA.
[0010] As a further improvement, a TVS diode, a filter capacitor, and a current-limiting resistor are connected in parallel between the positive signal input terminal and the negative signal input terminal of the above-mentioned multiple filter circuit.
[0011] The positive signal input terminal is connected in series with a first inductor and a first ferrite bead, and the first inductor and the first ferrite bead are grounded through a first decoupling capacitor.
[0012] The negative signal input terminal is connected in series with a second inductor and a second ferrite bead, and the second inductor and the second ferrite bead are grounded through a second decoupling capacitor.
[0013] The first and second magnetic beads are connected to a second-order RC filter circuit at their rear ends to form the output signal.
[0014] As a further improvement, the peak pulse power of the above-mentioned TVS tube is 600W and the response time is less than 5μs.
[0015] As a further improvement, the sampling chip mentioned above is the AD7606 chip, which is a differential input ADC chip with 16-bit resolution and a sampling rate of 1Msps. The output terminal of the second-order RC filter circuit mentioned above is connected to the INP pin and INM pin of the ADC chip.
[0016] As a further improvement, the signal processing unit receives the parallel port output signal of the sampling chip and includes a hardware-implemented Fourier transform module and a digital filtering module to eliminate common-mode voltage drift and noise.
[0017] Further improvements include a low-temperature drift reference voltage source with a temperature drift coefficient of less than 10 PPM / ℃, whose output is connected to the VREF pin of the AD7606.
[0018] Compared with the prior art, the beneficial effects of this utility model are:
[0019] Firstly, this invention achieves effective electromagnetic compatibility protection by setting an anti-interference circuit between the sensor module and the sampling chip, and combining it with EMC devices, isolation voltage transformers, and multiple filtering circuits. This significantly improves the circuit's anti-interference capability in strong electromagnetic interference environments and ensures the stability and accuracy of the sampling signal.
[0020] Secondly, by employing an isolation voltage transformer encapsulated in permalloy and a multi-stage filtering circuit, this invention effectively isolates common-mode interference in the input signal, reduces the impact of external noise on the signal, improves signal quality, ensures accurate sampling of high-precision analog signals, and thus enhances the anti-interference capability of the entire sampling circuit and the reliability of the system.
[0021] Thirdly, this utility model is equipped with a low-temperature drift reference voltage source, which is connected to the VREF pin of the AD7606 chip to ensure the stability of the reference voltage under temperature changes, thereby reducing temperature-induced errors, ensuring the consistency of ADC sampling accuracy under different working environments, and further improving the overall performance and accuracy of the sampling circuit. Attached Figure Description
[0022] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.
[0023] Figure 1 This is a structural block diagram of the present invention;
[0024] Figure 2 This is a schematic diagram of the anti-interference circuit in this utility model.
[0025] Figure label:
[0026] 1-Sensor module; 2-Anti-interference circuit; 3-Sampling chip; 4-Digital signal processing unit; 5-Low temperature drift reference voltage source;
[0027] 21-Multiple filter circuits; 211-Second-order RC filter circuit;
[0028] MOV - Varistor; T1 - Isolation Voltage Transformer; D1 - TVS Diode; C1 - Filter Capacitor; C2 - Second Capacitor; C3 - Third Capacitor; C4 - First Decoupling Capacitor; C5 - Second Decoupling Capacitor; R1 - Current Limiting Resistor; R2 - Second Resistor; R3 - Third Resistor; R4 - Fourth Resistor; R5 - Fifth Resistor; L1 - First Inductor; L2 - Second Inductor; FB1 - First Ferrite Bead; FB2 - Second Ferrite Bead. Detailed Implementation
[0029] To facilitate understanding by those skilled in the art, the structure of this utility model will now be described in further detail with reference to the accompanying drawings:
[0030] In the description of this utility model, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. The terms "part," "side," "end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this utility model.
[0031] like Figure 1As shown, this application provides a high-precision, strong anti-interference sampling circuit, including a sensor module 1. The output signal of the sensor module 1 is transmitted to a digital signal processing unit 4 via a sampling chip 3. An anti-interference circuit 2 is provided between the sensor module 1 and the sampling chip 3. In this technical solution, the sensor module 1 includes one or more high-input-impedance permalloy type sensors. The permalloy type sensors utilize the permalloy material to respond to changes in external physical quantities and generate signal output through its changing permeability. Permalloy material exhibits superior performance in magnetic shielding and electromagnetic interference suppression, which can effectively reduce the influence of external magnetic fields and improve signal conversion accuracy. At the same time, by utilizing its high input impedance characteristics, it effectively isolates interference signals in the input circuit, especially those noises that may be generated by line impedance mismatch, further improving the purity of the signal.
[0032] In one specific embodiment, sensor module 1 outputs an AC analog signal.
[0033] like Figure 2 As shown, the anti-interference circuit 2 includes an EMC device, an isolation voltage transformer T1, and a multiple filter circuit 21 connected in sequence.
[0034] In the above embodiment, the EMC device is a varistor (MOV) connected in parallel between the positive and negative signal input terminals of the anti-interference circuit 2, used for front-end protection of the anti-interference circuit 2. Preferably, the current-carrying capacity of the varistor (MOV) is not less than 3.5kA, enabling it to quickly conduct when the voltage at the signal input terminal exceeds a set threshold, absorbing surge current and preventing damage to circuit components. This structure helps protect subsequent circuits from transient voltages such as power surges or lightning strikes, significantly improving the circuit's anti-interference capability and long-term stability.
[0035] Furthermore, the isolation voltage transformer T1 uses a permalloy package. Permalloy packages have excellent magnetic shielding properties, effectively isolating the electrical coupling between the input signal and the circuit, especially in environments with strong electromagnetic interference, blocking the effects of common-mode interference and high-frequency noise.
[0036] like Figure 2 As shown, in this embodiment, a TVS diode D1, a filter capacitor C1, and a current-limiting resistor R1 are connected in parallel between the positive signal input terminal and the negative signal input terminal of the multiple filter circuit 21.
[0037] In this circuit structure, TVS diode D1 suppresses fast pulse interference, and filter capacitor C1 filters out high-frequency noise. Connected between the positive and negative signal inputs, it reduces the high-frequency noise filtering response of capacitor C1, enhancing circuit stability. Preferably, the peak pulse power of TVS diode D1 is 600W, ensuring it can withstand significant voltage surges and effectively suppress surge voltages within a short time, preventing damage to subsequent circuits from these transient voltages. The response time is less than 5μs, ensuring rapid overvoltage clamping and maintaining stable system operation.
[0038] Furthermore, the positive signal input terminal is connected in series with a first inductor L1 and a first ferrite bead FB1, and the first inductor L1 and the first ferrite bead FB1 are grounded through a first decoupling capacitor C4; the negative signal input terminal is connected in series with a second inductor L2 and a second ferrite bead FB2, and the second inductor L2 and the second ferrite bead FB2 are grounded through a second decoupling capacitor C5. The first inductor L1 and the second inductor L2 are used for high-frequency signal filtering, especially to remove high-frequency noise from the signal. Inductors have high impedance at high frequencies, which can effectively suppress electromagnetic interference and high-frequency spurious signals. The first ferrite bead FB1 and the second ferrite bead FB2 can effectively absorb and attenuate high-frequency noise, enhancing the circuit's anti-electromagnetic interference capability. The first decoupling capacitor C4 and the second decoupling capacitor C5 ground the high-frequency components of the signal, optimizing signal stability. The rear ends of the first ferrite bead FB1 and the second ferrite bead FB2 are connected to a second-order RC filter circuit 211 to form the output signal. Specifically, as... Figure 2 As shown, the second-order RC filter circuit 211 includes a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a second capacitor C2, and a third capacitor C3. The second resistor R2 and the fourth resistor R4 are connected in series in the positive signal input path of the circuit, and the third resistor R3 and the fifth resistor R5 are connected in series in the negative signal input path of the circuit. The second capacitor C2 is connected in parallel to the output terminals of the second resistor R2 and the third resistor R3, and the third capacitor C3 is connected in parallel to the output terminals of the fourth resistor R4 and the fifth resistor R5. The two ends of the third capacitor C3 form the output terminal of the anti-interference circuit 2, which is used to connect to the sampling chip 3. Through the above circuit structure, the sampling circuit can operate stably in scenarios with significant electromagnetic interference.
[0039] In one specific embodiment, the sampling chip 3 is an AD7606 ADC chip, which is a differential input ADC chip with 16-bit resolution and a sampling rate of 1Msps. The output of the second-order RC filter circuit 211 is connected to the INP pin and INM pin of the ADC chip.
[0040] The digital signal processing unit 4 receives the parallel port output signal from the sampling chip 3, including a hardware-implemented Fourier transform module and a digital filtering module, which are used to eliminate common-mode voltage drift and noise.
[0041] Specifically, after signal sampling, the ADC chip AD7606 converts the signal into a digital signal and outputs it via a parallel port. The digital signal processing unit 4 receives this output signal and performs further processing, including:
[0042] Fourier Transform Module (not shown in the figure): This module implements Fast Fourier Transform in hardware to convert time-domain signals into frequency-domain signals. Through frequency-domain analysis, it identifies and filters out noise components such as power frequency interference and harmonics, effectively removing interference signals and improving signal quality.
[0043] Digital filtering module (not shown in the figure): This module further performs digital filtering on the signal to eliminate residual noise and common-mode voltage drift, ensuring the purity of the output signal. Digital filtering can precisely control the filtering parameters, effectively remove unwanted noise frequency bands, and maintain the accuracy of the signal.
[0044] In addition, the digital signal processing unit 4 can smooth and correct the signal through fitting data algorithms, and correct the sampled signal according to historical data or preset standard models, thereby effectively eliminating errors caused by common-mode voltage drift and other interferences and improving the accuracy of the signal.
[0045] like Figure 1 As shown, to ensure the sampling accuracy of AD7606 under various operating environments, this technical solution incorporates a low-temperature drift reference voltage source 5 with a temperature drift coefficient of less than 10 PPM / ℃. Its output is connected to the VREF pin of AD7606 (not shown in the figure).
[0046] The low-temperature drift reference voltage source 5 provides a stable reference voltage for the AD7606, ensuring accurate sampling even in environments with significant temperature fluctuations. A temperature drift coefficient of less than 10 PPM / ℃ effectively reduces errors caused by temperature variations. Specifically, it ensures that the ADC's accuracy remains stable within the ideal error range over a temperature range of -40℃ to 85℃. The stability of the reference voltage source guarantees the high accuracy and reliability of the entire sampling circuit, providing consistently stable sampling performance, especially in harsh environments.
[0047] This invention significantly improves the stability and accuracy of the circuit under strong electromagnetic interference by incorporating multi-level protection in the anti-interference circuit 2. Through components such as the permalloy-encapsulated isolation voltage transformer T1, varistor MOV, multiple filter circuit 21, and TVS diode D1, surge current and transient voltage are effectively suppressed, ensuring signal integrity. Combined with Fourier transform or data fitting algorithms, common-mode voltage drift and other noise interference are further eliminated, improving signal accuracy and stability. This enables the system to adapt to various complex working environments and ensures long-term stable operation under high precision and high reliability requirements.
[0048] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.
Claims
1. A high-precision, high-interference-resistant sampling circuit, comprising a sensor module (1), wherein the output signal of the sensor module (1) is transmitted to a digital signal processing unit (4) via a sampling chip (3), characterized in that: An anti-interference circuit (2) is provided between the sensor module (1) and the sampling chip (3); The anti-interference circuit (2) includes an EMC device, an isolation voltage transformer (T1), and a multiple filter circuit (21) connected in sequence; The isolation voltage transformer (T1) is encapsulated with permalloy.
2. The high-precision, strong anti-interference sampling circuit as described in claim 1, characterized in that: The sensor module (1) includes one or more permalloy type sensors that output AC analog signals.
3. The high-precision, strong anti-interference sampling circuit as described in claim 2, characterized in that: The EMC device is a varistor (MOV) connected in parallel between the positive signal input terminal and the negative signal input terminal of the anti-interference circuit (2).
4. The high-precision, strong anti-interference sampling circuit as described in claim 3, characterized in that: The current carrying capacity of the varistor (MOV) is not less than 3.5kA.
5. The high-precision, strong anti-interference sampling circuit as described in claim 2, characterized in that: The positive signal input terminal and the negative signal input terminal of the multiple filtering circuit (21) are connected in parallel with a TVS transistor (D1), a filter capacitor (C1) and a current limiting resistor (R1). The positive signal input terminal is connected in series with a first inductor (L1) and a first ferrite bead (FB1), and the first inductor (L1) and the first ferrite bead (FB1) are grounded through a first decoupling capacitor (C4). The negative signal input terminal is connected in series with a second inductor (L2) and a second ferrite bead (FB2), and the second inductor (L2) and the second ferrite bead (FB2) are grounded through a second decoupling capacitor (C5); The first ferrite bead (FB1) and the second ferrite bead (FB2) are connected to a second-order RC filter circuit (211) to form an output signal.
6. The high-precision, strong anti-interference sampling circuit as described in claim 5, characterized in that: The peak pulse power of the TVS diode (D1) is 600W, and the response time is less than 5μs.
7. The high-precision, strong anti-interference sampling circuit as described in claim 5, characterized in that: The sampling chip (3) is an AD7606 chip, which is a differential input ADC chip with 16-bit resolution and 1Msps sampling rate. The output of the second-order RC filter circuit (211) is connected to the INP pin and INM pin of the ADC chip.
8. The high-precision, strong anti-interference sampling circuit as described in claim 7, characterized in that: The digital signal processing unit (4) is used to receive the output signal of the parallel port of the sampling chip (3), including a hardware-implemented Fourier transform module and a digital filtering module, which are used to eliminate common-mode voltage drift and noise.
9. The high-precision, strong anti-interference sampling circuit as described in claim 7, characterized in that: It also includes a low-temperature drift reference voltage source (5), whose temperature drift coefficient is less than 10PPM / ℃, and whose output is connected to the VREF pin of AD7606.