Homologous double-path synchronous sampling circuit for resistance precision detection and method thereof

Abstract

The application relates to a homologous double-path synchronous sampling method applied to resistance precision detection, which realizes double-channel synchronous acquisition based on reference measurement by synchronously sampling and data processing of two voltage signals in a circuit. The application also provides a homologous double-path synchronous sampling circuit, which comprises a homologous double-path detection circuit, a synchronous A / D sampling circuit and a data processing circuit; two voltage output by the homologous double-path detection circuit enters the synchronous A / D sampling circuit, the data processing circuit generates a group of control signals to control the synchronous A / D sampling circuit, the two synchronous A / D conversion data obtained by the synchronous A / D sampling circuit is processed in the data processing circuit, and the processed data is interacted with an upper computer; the data processing circuit inversely calculates the value of a to-be-detected resistance Rx according to the digital quantity obtained by converting VN1 and VN2 of the synchronous A / D sampling circuit and the topological structure form of the homologous double-path detection circuit, and then interacts with the upper computer. The application can sufficiently reduce detection errors caused by external interference and power fluctuation.

Description

Technical Field

[0001] This invention relates to a resistance detection technology, specifically to a dual-channel synchronous sampling circuit and method for precision resistance detection. Background Technology

[0002] In aerospace guidance and certain industrial fields, numerous turntables are used, and conductive slip rings, as electrical signal transmission devices, are a crucial component of these turntables. Their reliability directly impacts the quality of electrical signal transmission. Currently, existing conductive slip rings in this field suffer from several issues: some experience poor contact or increased contact resistance due to long-term wear and debris accumulation; others exhibit brush deformation caused by prolonged stress, leading to skipping points; some lack contact between the brush holder and the conductive ring due to brush holder deformation; and still others suffer from contact oxidation or dust accumulation due to prolonged exposure to harsh environments. These changes directly affect the performance of the slip ring turntable, and in some cases, even directly impact product testing results.

[0003] Currently, most commonly used resistance testers on the market use a single-point voltage sampling method. The speed and accuracy of the sampling cannot meet the accuracy requirements for detecting the contact resistance of conductive slip rings, and they are not suitable for detecting their dynamic characteristics. Summary of the Invention

[0004] This invention addresses the high-precision testing requirements for the dynamic and static characteristics of contact resistance in this type of contact by proposing a dual-channel synchronous detection method based on a reference measurement. This method achieves synchronous acquisition across two channels, significantly reducing detection errors caused by external interference and power fluctuations. The invention also provides a dual-channel synchronous sampling circuit that similarly solves the aforementioned technical problems.

[0005] This invention provides a synchronous sampling method for dual-channel detection of resistors, comprising the following steps: synchronously sampling two voltages VN1 and VN2 in the circuit through dual-channel detection; converting VN1 and VN2 to obtain digital quantities and the topology of dual-channel detection; back-calculating the value of the resistor Rx to be measured; and then interacting with the host computer.

[0006] The present invention also provides a synchronous dual-channel sampling circuit for implementing the sampling method, the circuit including a synchronous dual-channel detection circuit, a synchronous A / D sampling circuit and a data processing circuit;

[0007] The dual-path detection circuit outputs two voltages, VN1 and VN2, which enter the synchronous A / D sampling circuit. The data processing circuit generates a set of control signals to control the synchronous A / D sampling circuit. These control signals are timing signals that enable the two A / D sampling circuits synchronously.

[0008] The two synchronous A / D conversion data obtained by the synchronous A / D sampling circuit are processed in the data processing circuit, and the processed data is then interacted with the host computer. In the synchronous A / D sampling circuit, the two A / D converters perform sampling transformation in the same timing under the same set of control signals, and the same set of control signals is generated by the data processing circuit.

[0009] The data processing circuit calculates the value of the resistor Rx to be measured based on the digital quantity obtained by the synchronous A / D sampling circuit converting VN1 and VN2 and the topology of the dual-path detection circuit, and then interacts with the host computer.

[0010] Furthermore, the dual-channel detection circuit includes a voltage divider circuit, two instrumentation amplifier circuits, and two differential proportional operation circuits.

[0011] The voltage divider circuit includes a power supply Vc1, a resistor Rx to be measured, and a resistor Rc. The resistor Rx to be measured and the resistor Rc are connected in series, and a voltage divider voltage V1 is drawn between the resistor Rx to be measured and the resistor Rc. The power supply voltage Vc1 and the voltage divider voltage V1 are respectively passed through their respective instrumentation amplifiers and differential proportional amplifier circuits to obtain VN1 and VN2, which are then entered into the synchronous A / D sampling circuit.

[0012] The instrumentation amplifier circuit corresponding to power supply voltage Vc1 consists of gain resistor Rg1 and instrumentation amplifier N1, with the amplification factor A of the instrumentation amplifier. N1 The gain resistor Rg1 determines the gain amplifier circuit corresponding to the voltage divider voltage V1. It consists of the gain resistor Rg2 and the instrumentation amplifier N2. The amplification factor A of the instrumentation amplifier is determined by the gain resistor Rg2. N2 The gain depends on the value of its gain resistor Rg2. Since the gain resistors of both instrumentation amplifier circuits are the same (Rg1 = Rg2 = Rg), we have A. N1 =A N2 =A N ;

[0013] The differential proportional amplifier circuit corresponding to the power supply voltage Vc1 consists of a reference power supply Vref, operational amplifier N3, input resistor R2 at the positive input terminal of the operational amplifier, input resistor R1 at the negative input terminal of the operational amplifier, grounding resistor R3 at the positive input terminal of the operational amplifier, and feedback resistor R5 at the negative input terminal. The input resistor R2 at the positive input terminal of the operational amplifier and the input resistor R1 at the negative input terminal of the operational amplifier have the same value R, and the grounding resistor R3 at the positive input terminal of the operational amplifier and the feedback resistor R5 have the same value Rf, that is, R1=R2=R, R3=R5=Rf;

[0014] The differential proportional amplifier circuit corresponding to the voltage divider V1 consists of a reference power supply Vref, operational amplifier N4, input resistor R7 at the positive input terminal of the operational amplifier, input resistor R6 at the negative input terminal of the operational amplifier, grounding resistor R8 at the positive input terminal of the operational amplifier, and feedback resistor R4 at the negative input terminal. The input resistor R7 at the positive input terminal of the operational amplifier and the input resistor R6 at the negative input terminal of the operational amplifier have the same value R, and the grounding resistor R8 at the positive input terminal of the operational amplifier and the feedback resistor R4 have the same value Rf, that is, R6=R7=R, R4=R8=Rf.

[0015] Furthermore, the transfer function of the circuit:

[0016]

[0017]

[0018] Resistance to be measured:

[0019]

[0020] Furthermore, the dual-path detection circuit includes a Wheatstone bridge and two instrumentation amplifier circuits. The Wheatstone bridge consists of four arms: the resistor to be measured Rx and four other resistors Rz1, Rz2, Ry1, and Ry2. Each of Rz1, Ry1, and Ry2 forms a separate arm, and Rx and Rz2 are connected in series to form an arm Rx+Rz2. ​​Vc1 is applied between the Rz1 arm and the Rx+Rz2 arm, and between the Ry1 arm and the Ry2 arm. The voltage to be measured V3 is drawn between the Rz1 arm and the Ry1 arm. The voltage to be measured V4 is drawn between the Rx+Rz2 arm and the Ry2 arm. Rz1 and Rz2 have the same value Rz, and Ry1 and Ry2 have the same value Ry, i.e., Rz1 = Rz2 = Rz, Ry1 = Ry2 = Ry.

[0021] The voltages V3 and V4 to be measured are respectively passed through their respective instrumentation amplifiers N1 and N2 to obtain VN1 and VN2, which are then fed into the synchronous A / D sampling circuit; the amplification factor A of the instrumentation amplifiers N1 and N2 is... N1 and A N2 The gain depends on the magnitudes of its gain resistors Rg1 and Rg2, respectively. Taking Rg1 = Rg2 = Rg, we have A. N1 =A N2 =A N .

[0022] Furthermore, the transfer function of the circuit:

[0023]

[0024]

[0025] Resistance to be measured:

[0026] Rx = VN2*(Ry+Rz) / (VN1-VN2).

[0027] This invention addresses the high-precision testing requirements for the dynamic and static characteristics of contact resistance. It synchronously samples two voltages, VN1 and VN2, in the circuit using dual-channel co-source detection. Based on the conversion of VN1 and VN2 into digital values ​​and the topology of the dual-channel co-source detection, the value of the resistor under test, Rx, is calculated. Then, it interacts with the host computer, realizing dual-channel synchronous acquisition based on reference measurement, which significantly reduces the detection error caused by external interference and power fluctuations. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the same-source dual-channel synchronous sampling circuit of the present invention;

[0029] Figure 2 These are two circuit topologies for dual-path detection circuits originating from the same source;

[0030] Figure 3 This is a dual-path detection circuit of the same source according to an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the interface connecting the A / D sampling chip and the microcontroller according to an embodiment of the present invention;

[0032] Figure 5 This is a timing diagram of the control signals. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings.

[0034] This invention provides a synchronous sampling method for dual-channel detection of resistors. The method synchronously samples two voltages VN1 and VN2 in the circuit through dual-channel detection. Based on the conversion of VN1 and VN2 into digital values ​​and the topology of dual-channel detection, the value of the resistor Rx under test is calculated and then interacted with the host computer.

[0035] This invention also provides a synchronous dual-channel sampling circuit for precision resistance detection, comprising a synchronous dual-channel detection circuit, a synchronous A / D sampling circuit, and a data processing circuit, such as... Figure 1As shown in the diagram, Rx is the resistor under test, which participates in the formation of a dual-channel detection circuit. This circuit outputs two voltages, VN1 and VN2, which enter the synchronous A / D sampling circuit. The data processing circuit generates a set of control signals to control the synchronous A / D sampling circuit. The two synchronous A / D conversion data obtained by the synchronous A / D sampling circuit are processed in the data processing circuit, and the processed data is then exchanged with the host computer. The set of control signals generated by the data processing circuit is actually the timing signal that synchronously enables the two A / D sampling circuits. The two synchronous A / D conversion data can be in serial or parallel form. The processing method of the data processing circuit is to calculate the value of the resistor under test, Rx, based on the digital values ​​obtained from the conversion of VN1 and VN2 by the synchronous A / D sampling circuit and the topology of the dual-channel detection circuit, and then exchange this value with the host computer.

[0036] Dual-path detection circuits have two circuit topologies. Figure 2 (a) The topology includes a voltage divider circuit, two instrumentation amplifier circuits, and two differential proportional operation circuits.

[0037] The voltage divider circuit includes a power supply Vc1, a resistor Rx to be measured, and a resistor Rc. The resistor Rx to be measured and the resistor Rc are connected in series, and a voltage divider voltage V1 is drawn between the resistor Rx to be measured and the resistor Rc. The power supply voltage Vc1 and the voltage divider voltage V1 are respectively passed through their respective instrumentation amplifiers and differential proportional amplifier circuits to obtain VN1 and VN2, which are then entered into the synchronous A / D sampling circuit.

[0038] The instrumentation amplifier circuit corresponding to power supply voltage Vc1 consists of gain resistor Rg1 and instrumentation amplifier N1, with the amplification factor A of the instrumentation amplifier. N1 The gain resistor Rg1 determines the gain amplifier circuit corresponding to the voltage divider voltage V1. It consists of the gain resistor Rg2 and the instrumentation amplifier N2. The amplification factor A of the instrumentation amplifier is determined by the gain resistor Rg2. N2 The gain depends on the value of its gain resistor Rg2. Since the gain resistors of both instrumentation amplifier circuits are the same (Rg1 = Rg2 = Rg), we have A. N1 =A N2 =A N .

[0039] The differential proportional amplifier circuit corresponding to the power supply voltage Vc1 consists of a reference power supply Vref, operational amplifier N3, input resistor R2 at the positive input terminal of the operational amplifier, input resistor R1 at the negative input terminal of the operational amplifier, grounding resistor R3 at the positive input terminal of the operational amplifier, and feedback resistor R5 at the negative input terminal. The input resistor R2 at the positive input terminal of the operational amplifier and the input resistor R1 at the negative input terminal of the operational amplifier have the same value R, and the grounding resistor R3 at the positive input terminal of the operational amplifier and the feedback resistor R5 have the same value Rf, that is, R1=R2=R, R3=R5=Rf.

[0040] The differential proportional amplifier circuit corresponding to the voltage divider V1 consists of a reference power supply Vref, operational amplifier N4, input resistor R7 at the positive input terminal of the operational amplifier, input resistor R6 at the negative input terminal of the operational amplifier, grounding resistor R8 at the positive input terminal of the operational amplifier, and feedback resistor R4 at the negative input terminal. The input resistor R7 at the positive input terminal of the operational amplifier and the input resistor R6 at the negative input terminal of the operational amplifier have the same value R, and the grounding resistor R8 at the positive input terminal of the operational amplifier and the feedback resistor R4 have the same value Rf, that is, R6=R7=R, R4=R8=Rf.

[0041] Depend on Figure 2 (a) Based on the circuit topology and the above-mentioned parameters, the following transfer function can be obtained.

[0042]

[0043]

[0044] Figure 2 (b) is another topology, including a Wheatstone bridge and two instrumentation amplifier circuits. The Wheatstone bridge consists of four arms: the resistor to be measured Rx and four other resistors Rz1, Rz2, Ry1, and Ry2. Rz1, Ry1, and Ry2 each form a separate arm, while Rx and Rz2 are connected in series to form an arm Rx+Rz2. ​​Vc1 is applied between the Rz1 arm and the Rx+Rz2 arm, and between the Ry1 arm and the Ry2 arm. The voltage to be measured V3 is drawn between the Rz1 arm and the Ry1 arm; the voltage to be measured V4 is drawn between the Rx+Rz2 arm and the Ry2 arm. Rz1 and Rz2 have the same value Rz, and Ry1 and Ry2 have the same value Ry, i.e., Rz1 = Rz2 = Rz, Ry1 = Ry2 = Ry.

[0045] The voltages V3 and V4 to be measured are respectively passed through their respective instrumentation amplifiers N1 and N2 to obtain VN1 and VN2, which are then fed into the synchronous A / D sampling circuit; the amplification factor A of the instrumentation amplifiers N1 and N2 is... N1 and A N2 The gain depends on the magnitudes of its gain resistors Rg1 and Rg2, respectively. Taking Rg1 = Rg2 = Rg, we have A. N1 =A N2 =A N .

[0046] Depend on Figure 2 (b) Based on the circuit topology and the above-mentioned parameters, the following transfer function can be obtained.

[0047]

[0048]

[0049] Synchronous A / D sampling circuits refer to two A / D converters performing sampling and transformation in the same timing sequence under the same set of control signals. This method can weaken the transient changes in the applied voltage Vc1 in the voltage divider circuit or Wheatstone bridge, reducing the requirements on its electrical characteristics. Even if the power supply experiences surge changes or some transient changes caused by external interference, it will not affect the measurement accuracy of the final measured resistor Rx. The same set of control signals is generated by the data processing circuit.

[0050] The data processing circuit not only generates control signals for the two A / D converters, but also calculates the value of the resistor Rx to be measured based on the digital values ​​obtained from the conversion of VN1 and VN2 by the synchronous A / D sampling circuit and the topology of the dual-channel detection circuit. This value is then exchanged with the host computer. The transfer function of the dual-channel detection circuit can be used to deduce the value of Rx. The data processing circuit can be any CPU-based digital circuit topology. This CPU includes microcontrollers, DSPs, ARM processors, FPGAs, etc.

[0051] like Figure 2 From the circuit topology of (a), equation (5) can be obtained from the transfer function equations (1) and (2).

[0052]

[0053] like Figure 2 From the circuit topology of (b), equation (6) can be obtained from the transfer functions (3) and (4).

[0054] Rx=VN2*(Ry+Rz) / (VN1-VN2) (6)

[0055] It can be seen from equations (5) and (6) that the amplification factor A of the instrumentation amplifier is... N The value of is independent of the resistance value Rx to be measured, and can be directly designed as the simplest value of 1.

[0056] The data processing circuit can obtain the value of the resistor Rx to be measured based on the topology of the dual-path detection circuit and the corresponding calculation formulas (5) and (6).

[0057] like Figure 3 When the channel under test is normally connected (KkA, KkB closed), resistor Rx is the resistor under test, +3Vp is the applied voltage of the voltage divider circuit, +12V is the power supply for the instrumentation amplifier in the two-channel instrumentation amplifier circuit and the operational amplifier in the differential proportional amplifier circuit, and +3Vref is the reference power supply (which needs to be calibrated before use, and the voltage accuracy is not less than 100%), which participates in the construction of the differential proportional amplifier circuit.

[0058] The voltage divider circuit consists of a power supply of +3Vp, resistors Rx and Rc, with Rc having a value of 30 ohms and an accuracy of no less than ±1‰.

[0059] The two-channel instrumentation amplifier circuit consists of two instrumentation amplifiers N1 and N2, each with a gain set to 1. The selected amplifier is the Analog Devices AD8220TRMZ-EP, with a gain A of [missing value]. N The relationship between A and the gain resistor Rg is A N =1+(49.4kΩ / Rg), when Rg is not connected, the amplification factor is 1.

[0060] The circuit consists of two differential amplifiers: one circuit uses a +3V reference power supply, resistors R1-R4, and operational amplifier N3; the other circuit uses a +3V reference power supply, resistors R5-R8, and operational amplifier N4. The +3V reference power supply is an Analog Devices ADR4530ARZ, which outputs a +3V voltage after calibration with an accuracy of no less than ±0.02%.

[0061] In the voltage divider circuit, the two voltages +3Vp and V1 pass through their respective instrumentation amplifiers and differential amplifier circuits to obtain VN1 and VN2, which then enter the synchronous A / D sampling circuit. The resistors in the differential amplifier circuit are R1 = R2 = R5 = R6 = 10kΩ, R3 = R4 = R7 = R8 = Rf = 300kΩ, and their accuracy is no less than ±1‰.

[0062] Depend on Figure 3 Based on the circuit topology and the above-mentioned parameters, the following transfer function can be obtained.

[0063] VN1=30*[3-(+3Vp)].............(7)

[0064]

[0065] Synchronous A / D sampling circuit refers to the simultaneous sampling and transformation of two A / D converters under the same set of control signals. This method can weaken the transient changes in the applied voltage Vc1 in the voltage divider circuit or Wheatstone bridge, reducing the requirements on its electrical characteristics. Even if the power supply experiences surge changes or transient changes caused by external interference, it will not affect the measurement accuracy of the final measured resistor Rx. In this embodiment, the A / D sampling chip selected is the Analog Devices AD7656, a six-channel A / D converter from Analog Devices, which simultaneously transforms the output voltages VN1 and VN2 of the two co-source dual-channel detection circuits; the data processing circuit uses the Atmel Atmega88PA, an 8-bit AVR microcontroller. The interface diagram of the A / D sampling chip and the microcontroller is shown below. Figure 4 As shown, the timing diagram of the control signals is as follows: Figure 5 As shown.

[0066] like Figure 4 , Figure 5When the CONVSTA,B pin of the AD7656 A / D converter detects the rising edge of the I / O output of the Atmega88PA microcontroller, it initiates synchronous conversion of the corresponding ADC channels 1 and 3. After the A / D conversion is complete, the BUSY pin output signal changes from high to low. The microcontroller's I / O detects that the sample-and-hold amplifier of the A / D converter has entered tracking mode by reading the falling edge of the BUSY signal. At this moment, the microcontroller selects the converter's chip select signal. When the signal is set low, an ordered serial clock signal is output to the SCLK pin of the A / D converter, and the 16-bit data output from the DOUTA and DOUTB pins is read bit by bit.

[0067] In this embodiment, the microcontroller not only generates control signals for the two A / D converters, but also calculates the value of the resistor Rx to be measured based on the digital values ​​obtained from the conversion of VN1 and VN2 by the synchronous A / D sampling circuit and the topology of the dual-channel detection circuit. This value is then exchanged with the host computer. The value of Rx can be derived from the transfer function of the dual-channel detection circuit.

[0068] like Figure 3 The circuit topology can be obtained from the transfer function equations (7) and (8) to form equation (9).

[0069] Rx=30*[(90-VN1) / (90-VN2)-1] (9)

[0070] The data processing circuit can obtain the value of the resistor Rx to be measured based on the topology of the dual-path detection circuit and the corresponding calculation formula (9).

[0071] The above-described specific embodiments are limited to explaining and illustrating the technical solutions of the present invention, but do not constitute a limitation on the scope of protection of the claims. Those skilled in the art should understand that any new technical solutions obtained by making simple modifications or substitutions based on the technical solutions of the present invention fall within the scope of protection of the present invention.

Claims

1. A homologous double-channel synchronous sampling circuit applied to resistance precision detection, characterized in that, Homologous double path detection circuit, synchronous A / D sampling circuit and data processing circuit are included. The two voltage VN1 and VN2 outputted by the homologous double path detection circuit enter the synchronous A / D sampling circuit, and a group of control signals are generated by the data processing circuit to control the synchronous A / D sampling circuit. The two synchronous A / D conversion data obtained by the synchronous A / D sampling circuit are processed in the data processing circuit, and the processed data are interacted with the upper computer. The data processing circuit calculates the value of the to-be-measured resistor Rx according to the digital quantity converted by the synchronous A / D sampling circuit from VN1 and VN2 and the topology form of the homologous double path detection circuit, and interacts with the upper computer.

2. The homologous double-path synchronous sampling circuit applied to resistance precision detection according to claim 1, characterized in that, The homologous double path detection circuit includes a voltage dividing circuit, two instrument amplification circuits and two differential proportional operation circuits. The voltage dividing circuit includes a power supply Vc1, a to-be-measured resistor Rx and a resistor Rc. The to-be-measured resistor Rx and the resistor Rc are connected in series, and a voltage dividing voltage V1 is led out between the to-be-measured resistor Rx and the resistor Rc. The instrument amplification circuit corresponding to the power voltage Vc1 is composed of a gain resistor Rg1 and an instrument amplifier N1, and the amplification multiple A of the instrument amplifier is determined by the size of the gain resistor Rg1 N1 The instrument amplification circuit corresponding to the power voltage Vc1 is composed of a gain resistor Rg1 and an instrument amplifier N1, and the amplification multiple A of the instrument amplifier is determined by the size of the gain resistor Rg1 N2 The instrument amplification circuit corresponding to the power voltage Vc1 is composed of a gain resistor Rg1 and an instrument amplifier N1, and the amplification multiple A of the instrument amplifier is determined by the size of the gain resistor Rg1 N1 = A N2 = A N ; The power supply voltage Vc1 and the voltage dividing voltage V1 are respectively inputted into the respective instrument amplification circuits and the differential proportional amplification circuits to obtain VN1 and VN2, and then enter the synchronous A / D sampling circuit. The differential proportional amplification circuit corresponding to the power supply voltage Vc1 is composed of a reference power supply Vref, an operational amplifier N3, an input resistor R2 connected to the positive input terminal of the operational amplifier, an input resistor R1 connected to the negative input terminal of the operational amplifier, a ground resistor R3 connected to the positive input terminal of the operational amplifier and a feedback resistor R5 connected to the negative input terminal of the operational amplifier.

3. The homologous double-path synchronous sampling circuit applied to resistance precision detection according to claim 2, characterized in that, The differential proportional amplification circuit corresponding to the voltage dividing voltage V1 is composed of a reference power supply Vref, an operational amplifier N4, an input resistor R7 connected to the positive input terminal of the operational amplifier, an input resistor R6 connected to the negative input terminal of the operational amplifier, a ground resistor R8 connected to the positive input terminal of the operational amplifier and a feedback resistor R4 connected to the negative input terminal of the operational amplifier. The transfer function of the circuit is: The to-be-measured resistor is:

4. The homologous double-path synchronous sampling circuit applied to resistance precision detection according to claim 1, characterized in that, The homologous double path detection circuit includes Wheatstone bridge and two-way instrument amplification circuit; the Wheatstone bridge is composed of the measured resistance Rx and other four resistances Rz1, Rz2, Ry1 and Ry2, wherein Rz1, Ry1 and Ry2 are respectively a bridge arm, Rx and Rz2 are connected in series to form a bridge arm Rx+Rz2; Vc1 is applied between the Rz1 bridge arm and the Rx+Rz2 bridge arm, the Ry1 bridge arm and the Ry2 bridge arm are grounded, the voltage V3 to be measured is led out between the Rz1 bridge arm and the Ry1 bridge arm, the voltage V4 to be measured is led out between the Rx+Rz2 bridge arm and the Ry2 bridge arm; wherein Rz1 and Rz2 take the same value Rz, and Ry1 and Ry2 take the same value Ry, that is, Rz1=Rz2=Rz, Ry1=Ry2=Ry; The to-be-measured voltages V3 and V4, after passing through respective instrument amplifiers N1 and N2, obtain VN1 and VN2, and then enter a synchronous A / D sampling circuit; the amplification factor A of the instrument amplifiers N1 and N2 N1 and A N2 are respectively determined by the size of gain resistors Rg1 and Rg2, and taking Rg1=Rg2=Rg, A N1 =A N2 =A N .

5. The homologous double-path synchronous sampling circuit applied to resistance precision detection according to claim 4, characterized in that, The transfer function of the circuit is: The resistance to be measured is: Rx=VN2*(Ry+Rz) / (VN1-VN2).

Images