Driving system and measurement method for suppressing small resistance measurement errors

Abstract

A drive system and a measurement method for suppressing errors in the measurement of small resistors belong to the field of precision measurement. The invention solves the problem that a drive system for measuring small resistors is difficult to suppress low-frequency noise and cannot achieve high-precision measurement of small resistors. The drive system of the invention is used to convert the low-frequency voltage signals at the high and low voltage ends of the resistor to be measured into high-frequency voltage signals, and the drive system is constructed by JFET switch tubes K1 and K2. A transient compensation circuit is used to suppress the transient voltage of the JFET switch tube K1. The switch tube drive circuit is used as a feedback loop to ensure that the gate-source voltage of the JFET switch tubes K1 and K2 is zero, thereby suppressing the sudden change caused by noise. The invention is mainly used for high-precision small resistor measurement.

Description

Technical Field

[0001] The present invention belongs to the field of precision measurement, and in particular relates to a driving system for suppressing small resistance measurement errors. Background Art

[0002] As a fundamental physical quantity in electricity, the ability to accurately measure resistance plays a vital role in scientific research, production, and equipment development. Resistance measurement indirectly impacts the development of high-end equipment, and the implementation of many new technologies also requires precise resistance measurement. For example, in the field of temperature measurement, the most widely used temperature sensor is the platinum resistor, which primarily utilizes its varying resistance values ​​at different temperatures, along with its high stability, high precision, and near-linear linearity within the medium temperature range (-200 to 650°C). Therefore, most high-precision thermometers used in the market utilize high-precision platinum resistors to measure their resistance.

[0003] In recent years, some progress has been made in high-precision measurement of small resistors. However, with the increasing demand for precision, measuring small resistors remains a challenging task. The typical method for measuring resistance is to apply a current to the resistor under test and read the voltage across it to determine the resistance value. When measuring small resistors, applying a large current can cause the voltage across the resistor to be too large, potentially breaking down the oxide layer on the resistor's surface, resulting in a measured resistance value lower than the actual value. This can also cause irreparable damage to the resistor due to noise. Even if this damage doesn't occur, prolonged high current flow through the resistor can cause temperature changes across the resistor, causing a change in resistance. Therefore, accurate measurement of small resistors requires applying a small current. However, the voltage generated by a small current through the resistor is very small, and accurate measurement requires mitigating various errors. Especially when the resistance is less than 1Ω, errors such as thermal potential and wire resistance can significantly interfere with the measurement, causing the measured result to deviate significantly from the actual value. Therefore, a suitable measurement drive system is needed to mitigate these errors and improve measurement accuracy.

[0004] Traditional drive systems for suppressing errors in micro-resistance measurements suffer from an inability to filter out low-frequency noise, hindering measurement accuracy. Micro-resistance generally refers to resistors with values ​​less than 1Ω. Current drive systems for measuring micro-resistance primarily employ a four-wire wiring system and bias voltage compensation to suppress wire resistance and thermoelectric potential. Filter circuits are used to filter out other errors. While this approach improves measurement accuracy to a certain extent, its current maximum accuracy is in the milli-Ω range, which is insufficient for high-precision measurements. Analysis reveals that the main reason for this is that filter circuits are effective at filtering out noise with significantly different frequencies from the signal, but struggle to filter out errors with similar frequencies. Low-frequency noise, primarily 1 / f noise and temperature drift, is the most significant error. Therefore, to improve measurement accuracy and meet the device's required maximum uncertainty of 0.009% within the 0-1Ω range, it is necessary to suppress this low-frequency noise. Therefore, a drive circuit designed to suppress micro-resistance measurement errors is needed to meet the requirements for high-precision micro-resistance measurement. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem that the driving system for measuring small resistors is difficult to suppress low-frequency noise and cannot achieve high-precision measurement of small resistors. The present invention provides a driving system and a measurement method for suppressing small resistor measurement errors.

[0006] A drive system that suppresses small resistance measurement errors. The drive system is used to X The low-frequency voltage signals at the high and low voltage ends are converted into high-frequency voltage signals, and the driving system thereof includes a constant current source, a transient compensation circuit, a switch tube driving circuit, a first voltage follower, an analog switch K3, and JFET switch tubes K1 and K2;

[0007] The constant current source outputs 10mA; the JFET switches K1 and K2 operate asynchronously; the transient compensation circuit is used to suppress the transient voltage of the JFET switch K1;

[0008] The constant current source is connected to the resistance to be measured R through the analog switch K3. X The high voltage end is connected to the resistance to be measured R X The high-voltage end is also connected to the source of the JFET switch tube K1 and the first input and output end of the transient compensation circuit. The drain of the JFET switch tube K1 is simultaneously connected to the second input and output end of the transient compensation circuit, the input end of the first voltage follower, and the drain of the JFET switch tube K2. The output of the high-pass filter serves as the output of the drive system. The output end of the first voltage follower is simultaneously connected to the reference voltage input end of the transient compensation circuit and the feedback input end of the switch tube drive circuit.

[0009] The first and second control output terminals of the switch tube driving circuit are connected to the gates of the JFET switch tubes K1 and K2 respectively;

[0010] Resistance to be measured R X The low voltage end is connected to the source of the JFET switch tube K2 and then to the power ground; the drain of the JFET switch tube K1 and the drain of the JFET switch tube K2 both serve as the output end of the drive system to output a high-frequency voltage signal.

[0011] Preferably, the switch tube driving circuit includes resistors R1 to R4 and two gate drivers;

[0012] The driving signal output terminal of the first gate driver is connected to one end of the resistor R1 and one end of the resistor R2 at the same time, and the other end of the resistor R1 serves as the first output terminal of the switch tube driving circuit;

[0013] The driving signal output terminal of the second gate driver is connected to one end of the resistor R3 and one end of the resistor R4 at the same time, and the other end of the resistor R4 serves as the second output terminal of the switch tube driving circuit;

[0014] The other end of the resistor R2 and the other end of the resistor R3 are connected to serve as the feedback input end of the switch tube driving circuit.

[0015] Preferably, the transient compensation circuit includes a single chip microcomputer, a D / A converter, resistors R5 to R6, and capacitors C1 to C2;

[0016] The control signal output terminal of the single chip microcomputer is connected to the control signal input terminal of the D / A converter, and the data input terminal of the D / A converter serves as the reference voltage input terminal of the transient compensation circuit;

[0017] The data output terminal of the D / A converter is connected to one end of the resistor R5 and one end of the resistor R6. The other end of the resistor R5 is connected to one end of the capacitor C1. The other end of the capacitor C1 serves as the first input and output terminal of the transient compensation circuit.

[0018] The other end of the resistor R6 is connected to one end of the capacitor C2 , and the other end of the capacitor C2 serves as a second input and output end of the transient compensation circuit.

[0019] Preferably, the driving system for suppressing small resistance measurement errors further includes high-voltage and low-voltage end high-frequency noise suppression circuits; wherein the low-voltage end high-frequency noise suppression circuit is connected in series with the resistance to be measured R X between the low-voltage end of the JFET switch tube K2 and the source of the JFET switch tube K2, which is used to suppress the resistance to be measured R X The high-frequency noise suppression circuit at the low-voltage end is connected in series with the resistor to be measured R X between the high voltage end of the JFET switch tube K1 and the source of the JFET switch tube K1, which is used to suppress the resistance to be measured R X High-frequency noise at the high-voltage end.

[0020] Preferably, the low-voltage end high-frequency noise suppression circuit includes a first polarity conversion circuit, a first inductor mutual inductor and a second voltage follower;

[0021] The first polarity conversion circuit is used to reverse the polarity of the input voltage;

[0022] The input terminal of the second voltage follower is connected to the resistance to be measured R X The low-voltage end of the first inductor transformer is connected to the same-name end of the secondary side W4, and the opposite-name end of the secondary side W4 is connected to the source of the JFET switch tube K2;

[0023] The output end of the second voltage follower is connected to the input end of the first polarity conversion circuit. The output end of the first polarity conversion circuit is connected to the same-name end of the primary side W3 of the first inductor transformer. The opposite-name end of the primary side W3 is connected to the power ground.

[0024] Preferably, the high-voltage end high-frequency noise suppression circuit includes a second polarity conversion circuit, a second inductor mutual inductor and a third voltage follower;

[0025] The second polarity conversion circuit is used to reverse the polarity of the input voltage;

[0026] The input terminal of the third voltage follower is connected to the resistance to be measured R X The high voltage end of the second inductor transformer is connected to the same-name end of the secondary side W1 of the second inductor transformer, and the opposite-name end of the secondary side W1 is connected to the source of the JFET switch tube K1;

[0027] The output end of the third voltage follower is connected to the input end of the second polarity conversion circuit. The output end of the second polarity conversion circuit is connected to the same-name end of the primary side W2 of the second inductor transformer. The opposite-name end of the primary side W2 is connected to the power ground.

[0028] Preferably, when the drive system is drawn on a circuit board, a ground ring is used around the JFET switches K1 and K2 for isolation.

[0029] Preferably, the resistance to be measured R is connected to the copper shielded wire and the terminal. X Connect to JFET switch tubes K1 and K2.

[0030] Preferably, the driving system for suppressing small resistance measurement errors further includes an amplifier and a high-pass filter;

[0031] The drain of the JFET switch tube K1 and the drain of the JFET switch tube K2 are both connected to the input end of the amplifier, and the output end of the amplifier is connected to the input end of the high-pass filter.

[0032] The measurement method implemented by the driving system for suppressing small resistance measurement errors is a high-frequency two-terminal measurement method. Specifically, after closing the analog switch K3, the JFET switch tube K1 is controlled to be turned on and the JFET switch tube K2 is turned off. At this time, the voltage output by the drain of the JFET switch tube K1 is the resistance to be measured R X The high voltage terminal voltage V1 is then controlled to turn off the JFET switch tube K1 and turn on the JFET switch tube K2. At this time, the voltage output by the drain of the JFET switch tube K2 is the resistance to be measured R X The low voltage end V2, calculate the resistance to be measured R X The differential voltage V between the two ends is V1-V2. According to the differential voltage V and the current flowing through the resistor to be measured R X The current I on R X＝ V / I.

[0033] Advantages of the present invention:

[0034] After analyzing the error in measuring tiny resistances, it was found that the main factor affecting the measurement accuracy was low-frequency noise, and since the useful signal is a DC signal, the low-frequency noise is difficult to filter out; therefore, the present invention provides a driving system and a measurement method for suppressing the error in measuring tiny resistances. The driving system is used to convert the low-frequency voltage signals at the high and low voltage ends of the resistance to be measured into high-frequency voltage signals. The process of converting the low-frequency voltage signal into a high-frequency voltage signal performs frequency separation on the useful signal and the low-frequency noise, so subsequent high-pass filtering can well filter the low-frequency noise of the low-frequency voltage signal, effectively suppress the low-frequency noise, and when the constant current source outputs a constant current of 10mA, the requirement for high-precision measurement of tiny resistances is met.

[0035] Since the resistance to be measured R X The input is a tiny resistor, and the voltage generated by a constant 10mA current flowing through the tiny resistor is a weak signal. Therefore, the switching process of converting the low-frequency voltage signal into a high-frequency voltage signal needs to ensure the signal-to-noise ratio of the signal. If a traditional analog switch is used to specially design the drive system, the on-resistance of the analog switch will change with the input voltage of the analog switch, and the on-resistance flatness of the analog switch will also have a great impact on the measurement, which may cause non-periodic fluctuations in the signal. Therefore, the present invention uses JFET switch tubes K1 and K2 to specially design the drive system, effectively avoiding non-periodic fluctuations in the signal, and further providing an accurate data basis for subsequent precise measurements.

[0036] The present invention also designs a signal feedback channel, that is, the switch tube drive circuit is used as a feedback loop to ensure that the gate-source voltage of the JFET switch tubes K1 and K2 is zero. When the JFET switch tube is controlled to be turned on, the gate voltage changes in real time with the input signal, which not only ensures that the gate-source voltage is zero when the JFET tube is turned on, but also prevents voltage mutations to a certain extent and suppresses mutations caused by noise.

[0037] As a high-frequency switching device, the JFET switch tube has a very fast switching speed. Due to the existence of its parasitic capacitance, there will be a voltage overshoot in the switching transient. The overshoot not only increases the possibility of damaging the device, but also introduces high-frequency noise. Therefore, a transient compensation circuit is added to eliminate the transient voltage overshoot of the JFET switch tube K1, thereby suppressing the interference caused by the switching transient. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of the structure of the driving system for suppressing small resistance measurement errors according to the present invention;

[0039] Figure 2 It is a structural diagram of the high-frequency noise suppression circuit at the high and low voltage ends. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0041] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0042] Specific implementation method 1: Figure 1 The present embodiment describes a driving system for suppressing small resistance measurement errors. The driving system is used to measure the resistance R X The low-frequency voltage signals at the high and low voltage ends are converted into high-frequency voltage signals, and the driving system thereof includes a constant current source, a transient compensation circuit, a switch tube driving circuit, a first voltage follower, an analog switch K3, and JFET switch tubes K1 and K2;

[0043] The constant current source outputs 10mA; the JFET switches K1 and K2 operate asynchronously; the transient compensation circuit is used to suppress the transient voltage of the JFET switch K1;

[0044] The constant current source is connected to the resistance to be measured R through the analog switch K3. X The high voltage end is connected to the resistance to be measured R XThe high-voltage end is also connected to the source of the JFET switch tube K1 and the first input and output end of the transient compensation circuit. The drain of the JFET switch tube K1 is simultaneously connected to the second input and output end of the transient compensation circuit, the input end of the first voltage follower, and the drain of the JFET switch tube K2. The output of the high-pass filter serves as the output of the drive system. The output end of the first voltage follower is simultaneously connected to the reference voltage input end of the transient compensation circuit and the feedback input end of the switch tube drive circuit.

[0045] The first and second control output terminals of the switch tube driving circuit are connected to the gates of the JFET switch tubes K1 and K2 respectively;

[0046] Resistance to be measured R X The low voltage end is connected to the source of the JFET switch tube K2 and then to the power ground; the drain of the JFET switch tube K1 and the drain of the JFET switch tube K2 both serve as the output end of the drive system to output a high-frequency voltage signal.

[0047] The present invention provides a drive system and a measurement method for suppressing errors in the measurement of small resistances. The drive system is used to convert low-frequency voltage signals at the high and low voltage ends of a resistance to be measured into high-frequency voltage signals. The process of converting the low-frequency voltage signal into a high-frequency voltage signal performs frequency separation on the useful signal and the low-frequency noise. Therefore, subsequent high-pass filtering can well filter the low-frequency noise of the low-frequency voltage signal, effectively suppressing the low-frequency noise. Moreover, when a constant current source outputs a constant current of 10mA, the requirement for high-precision measurement of small resistances is met.

[0048] The constant current source is used to generate a high stability current of 10mA.

[0049] The analog switch K3 is used to control whether to apply a current value to the resistor to be measured. When the current I flows through the resistor to be measured R x When the voltage to be measured is generated, the voltage to be measured is appropriately measured and calculated to obtain the resistance value of the resistor to be measured.

[0050] Since the input of the resistor to be measured Rx is a small signal, the switching process of converting the low-frequency voltage signal into a high-frequency voltage signal needs to ensure the signal-to-noise ratio. If a traditional analog switch is used to specially design the drive system, the analog switch on-resistance will change with the analog switch input voltage, and the on-resistance flatness will also have a great impact on the measurement, which may cause the signal to fluctuate non-periodically. In addition, the parasitic capacitance and on-resistance of the traditional analog switch cannot be achieved at the same time. In order to reduce the attenuation of the signal, a low on-resistance is required, but a low on-resistance requires a larger chip area, which will introduce a larger input capacitance, resulting in a slow switching time. Therefore, the traditional analog switch cannot complete the task of high-speed switching and will also have a great impact on the accuracy. Therefore, in order to achieve the task of high-speed switching and improve the accuracy and signal-to-noise ratio of the small signal transmission process, the present invention selects a JFET switch tube as a switch to specially design the drive system. When the gate-source voltage is zero, the on-resistance is basically unchanged, and compared with the analog switch and transistor noise, the noise is very small, which is very suitable for the transmission of small signals, effectively avoiding the non-periodic fluctuation of the signal, and further providing an accurate data basis for subsequent precise measurement.

[0051] The present invention also designs a feedback channel, that is, the switch tube driving circuit is used as a feedback loop to ensure that the gate-source voltage of the JFET switch tubes K1 and K2 is zero. When the JFET switch tube is controlled to be turned on, the gate voltage changes in real time with the input signal, which not only ensures that the gate-source voltage is zero when the JFET tube is turned on, but also prevents voltage mutations to a certain extent and suppresses mutations caused by noise.

[0052] As a high-frequency switching device, the JFET switch tube has a very fast switching speed. Due to the existence of its parasitic capacitance, there will be a voltage overshoot in the switching transient. The overshoot not only increases the possibility of damaging the device, but also introduces high-frequency noise. Therefore, a transient compensation circuit is added to eliminate the transient voltage overshoot of the JFET switch tube K1, thereby suppressing the interference caused by the switching transient.

[0053] The present invention also designs a feedback channel, that is, using the switch tube drive circuit as a feedback loop to ensure that the gate-source voltage of the JFET switches K1 and K2 is zero. When the JFET switch tube is controlled to turn on, the gate voltage changes in real time with the input signal. This not only ensures that the gate-source voltage is zero when the JFET tube is turned on, but also prevents sudden voltage changes to a certain extent, suppressing sudden changes caused by noise. Specifically, the specific structure of the switch tube drive circuit is as follows:

[0054] See also Figure 1 , the switch tube driving circuit includes resistors R1 to R4 and two gate drivers;

[0055] The driving signal output terminal of the first gate driver is connected to one end of the resistor R1 and one end of the resistor R2 at the same time, and the other end of the resistor R1 serves as the first output terminal of the switch tube driving circuit;

[0056] The driving signal output terminal of the second gate driver is connected to one end of the resistor R3 and one end of the resistor R4 at the same time, and the other end of the resistor R4 serves as the second output terminal of the switch tube driving circuit;

[0057] The other end of the resistor R2 and the other end of the resistor R3 are connected to serve as the feedback input end of the switch tube driving circuit.

[0058] See also Figure 1 , the transient compensation circuit includes a single chip microcomputer, a D / A converter, resistors R5 to R6, and capacitors C1 to C2;

[0059] The control signal output terminal of the single chip microcomputer is connected to the control signal input terminal of the D / A converter, and the data input terminal of the D / A converter serves as the reference voltage input terminal of the transient compensation circuit;

[0060] The data output terminal of the D / A converter is connected to one end of a resistor R5 and one end of a resistor R6. The other end of the resistor R5 is connected to one end of a capacitor C1, and the other end of the capacitor C1 serves as a first input and output terminal of the transient compensation circuit. The other end of the resistor R6 is connected to one end of a capacitor C2, and the other end of the capacitor C2 serves as a second input and output terminal of the transient compensation circuit.

[0061] In this preferred embodiment, the JFET switch tube, as a high-frequency switching device, switches very quickly. Due to its parasitic capacitance, switching transients can cause voltage overshoots. This overshoot not only increases the likelihood of device damage but also introduces high-frequency noise. Therefore, a transient compensation circuit is added to eliminate the transient voltage overshoot of the JFET switch tube K1, thereby suppressing interference caused by switching transients. Specifically, in normal operation, the capacitor blocks DC and does not interfere with the circuit. However, at the moment of switching on or off, the negative voltage output by the D / A converter compensates for this, eliminating the voltage overshoot during switching transients and thus suppressing interference caused by switching transients.

[0062] Specifically, the driving system for suppressing small resistance measurement errors also includes high-frequency noise suppression circuits at high and low voltage ends; wherein,

[0063] The low-voltage high-frequency noise suppression circuit is connected in series with the resistor to be measured R X between the low-voltage end of the JFET switch tube K2 and the source of the JFET switch tube K2, which is used to suppress the resistance to be measured R X High-frequency noise at the low-voltage end;

[0064] The high-voltage end high-frequency noise suppression circuit is connected in series with the resistor to be measured R X between the high voltage end of the JFET switch tube K1 and the source of the JFET switch tube K1, which is used to suppress the resistance to be measured R X High-frequency noise at the high-voltage end.

[0065] For details, see Figure 2 , the low-voltage end high-frequency noise suppression circuit includes a first polarity conversion circuit, a first inductor mutual inductor and a second voltage follower;

[0066] The first polarity conversion circuit is used to reverse the polarity of the input voltage;

[0067] The input terminal of the second voltage follower is connected to the resistance to be measured R X The low-voltage end of the first inductor transformer is connected to the same-name end of the secondary side W4, and the opposite-name end of the secondary side W4 is connected to the source of the JFET switch tube K2;

[0068] The output end of the second voltage follower is connected to the input end of the first polarity conversion circuit. The output end of the first polarity conversion circuit is connected to the same-name end of the primary side W3 of the first inductor transformer. The opposite-name end of the primary side W3 is connected to the power ground.

[0069] The high-voltage end high-frequency noise suppression circuit includes a second polarity conversion circuit, a second inductor mutual inductor and a third voltage follower;

[0070] The second polarity conversion circuit is used to reverse the polarity of the input voltage;

[0071] The input terminal of the third voltage follower is connected to the resistance to be measured R X The high voltage end of the second inductor transformer is connected to the same-name end of the secondary side W1 of the second inductor transformer, and the opposite-name end of the secondary side W1 is connected to the source of the JFET switch tube K1;

[0072] The output end of the third voltage follower is connected to the input end of the second polarity conversion circuit. The output end of the second polarity conversion circuit is connected to the same-name end of the primary side W2 of the second inductor transformer. The opposite-name end of the primary side W2 is connected to the power ground.

[0073] In this preferred embodiment, inductor transformers W1-W4 are added to the input for compensation. This has no impact on the DC signal, but high-frequency noise is collected by the voltage follower. Passing through the polarity conversion circuit, the voltage changes from positive to negative. Since this is high-frequency noise, it can be coupled from W2 to the W1 input channel, thereby eliminating the high-frequency noise introduced by the current loop. In other words, the two inductor transformers couple the high-frequency noise voltage of opposite polarity output by the polarity conversion circuit to the input channel, thereby eliminating the interference of high-frequency noise. However, the DC voltage generated by the DC current cannot be coupled to the input channel, thereby ensuring the accuracy of the input channel and improving the signal-to-noise ratio of the input voltage signal.

[0074] Furthermore, when the drive system is drawn on a circuit board, a ground ring is used around the JFET switches K1 and K2 to isolate high-frequency noise. Because the JFET switches K1 and K2 need to be frequently turned on and off during the measurement process, they are prone to introducing high-frequency noise. Using a ground ring for isolation can greatly prevent the coupling of useful signals and high-frequency noise, thereby reducing the noise introduced by the signal in the transmission channel and improving the signal-to-noise ratio of the input signal.

[0075] In specific applications, use copper shielded wires and terminal blocks to connect the resistance to be measured R X Connected to JFET switches K1 and K2, it isolates external electromagnetic interference, including high-frequency signal interference such as radio frequency interference and magnetic field interference.

[0076] Furthermore, the driving system for suppressing small resistance measurement errors also includes an amplifier and a high-pass filter; the drain of the JFET switch tube K1 and the drain of the JFET switch tube K2 are both connected to the input end of the amplifier, and the output end of the amplifier is connected to the input end of the high-pass filter.

[0077] In this preferred embodiment, an amplifier and a high-pass filter are added to amplify and filter the high-frequency voltage signals output by the JFET switches K1 and K2. Since the high-pass filter has an attenuation effect on the signal, if filtering is performed directly, the tiny signal may be further attenuated, which will affect the measurement results. Therefore, the signal is amplified first and then filtered. At this time, the attenuation of the useful signal by the high-pass filter can be ignored, ensuring that the low-frequency signal is filtered out while ensuring the quality of the signal.

[0078] Specific embodiment 2: A measurement method implemented by the drive system for suppressing small resistance measurement errors is a high-frequency two-terminal measurement method. Specifically, after closing the analog switch K3, the JFET switch tube K1 is controlled to be turned on and the JFET switch tube K2 is turned off. At this time, the voltage output by the drain of the JFET switch tube K1 is the resistance to be measured R X The high voltage terminal voltage V1 is then controlled to turn off the JFET switch tube K1 and turn on the JFET switch tube K2. At this time, the voltage output by the drain of the JFET switch tube K2 is the resistance to be measured R X The low voltage end V2, calculate the resistance to be measured R X The differential voltage V between the two ends is V1-V2. According to the differential voltage V and the current flowing through the resistor to be measured R X The current I on R X＝ V / I.

[0079] In this embodiment, a high-frequency two-terminal measurement method is used to modulate the small differential mode signal input to the resistor to be measured, so that in one measurement cycle, half a cycle is the voltage at the high-voltage end of the resistor to be measured, and half a cycle is the voltage at the low-voltage end of the resistor to be measured. The difference between the two ends of the resistor to be measured can be calculated later; according to the differential voltage and the current flowing through the resistor to be measured R X The current I on the resistor is used to obtain the resistance value of the resistor to be measured.

[0080] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the invention. It should be understood that many modifications may be made to the illustrative embodiments, and that other arrangements may be devised, without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in ways other than those described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be employed in conjunction with other described embodiments.

Claims

1. A drive system for suppressing minute resistance measurement errors, characterized in that: The drive system is used to connect the resistance to be measured R X The low-frequency voltage signals at the high and low voltage ends are converted into high-frequency voltage signals, and the driving system thereof includes a constant current source, a transient compensation circuit, a switch tube driving circuit, a first voltage follower, an analog switch K3, and JFET switch tubes K1 and K2; The constant current source outputs 10mA; the JFET switches K1 and K2 operate asynchronously; the transient compensation circuit is used to suppress the transient voltage of the JFET switch K1; The constant current source is connected to the resistance to be measured R through the analog switch K3. X The high voltage end is connected to the resistance to be measured R X The high-voltage end is also connected to the source of the JFET switch tube K1 and the first input and output end of the transient compensation circuit. The drain of the JFET switch tube K1 is simultaneously connected to the second input and output end of the transient compensation circuit, the input end of the first voltage follower, and the drain of the JFET switch tube K2. The output of the high-pass filter serves as the output of the drive system. The output end of the first voltage follower is simultaneously connected to the reference voltage input end of the transient compensation circuit and the feedback input end of the switch tube drive circuit. The first and second control output terminals of the switch tube driving circuit are connected to the gates of the JFET switch tubes K1 and K2 respectively; Resistor to be measured R X The low voltage end is connected to the source of the JFET switch tube K2 and then to the power ground; the drain of the JFET switch tube K1 and the drain of the JFET switch tube K2 both serve as the output end of the drive system to output a high-frequency voltage signal.

2. The driving system for suppressing small resistance measurement errors according to claim 1, characterized in that: The switch tube driving circuit includes resistors R1 to R4 and two gate drivers; The driving signal output terminal of the first gate driver is connected to one end of the resistor R1 and one end of the resistor R2 at the same time, and the other end of the resistor R1 serves as the first output terminal of the switch tube driving circuit; The driving signal output terminal of the second gate driver is connected to one end of the resistor R3 and one end of the resistor R4 at the same time, and the other end of the resistor R4 serves as the second output terminal of the switch tube driving circuit; The other end of the resistor R2 and the other end of the resistor R3 are connected to serve as the feedback input end of the switch tube driving circuit.

3. The driving system for suppressing small resistance measurement errors according to claim 1, characterized in that: The transient compensation circuit includes a single chip microcomputer, a D / A converter, resistors R5 to R6, and capacitors C1 to C2; The control signal output terminal of the single-chip microcomputer is connected to the control signal input terminal of the D / A converter, and the data input terminal of the D / A converter serves as the reference voltage input terminal of the transient compensation circuit; the data output terminal of the D / A converter is connected to one end of a resistor R5 and one end of a resistor R6 at the same time; the other end of the resistor R5 is connected to one end of a capacitor C1, and the other end of the capacitor C1 serves as the first input and output terminal of the transient compensation circuit; the other end of the resistor R6 is connected to one end of a capacitor C2, and the other end of the capacitor C2 serves as the second input and output terminal of the transient compensation circuit.

4. The driving system for suppressing small resistance measurement errors according to claim 1, characterized in that: It also includes high-voltage and low-voltage high-frequency noise suppression circuits; wherein the low-voltage high-frequency noise suppression circuit is connected in series with the resistor to be measured R X between the low-voltage end of the JFET switch tube K2 and the source of the JFET switch tube K2, which is used to suppress the resistance to be measured R X The high-frequency noise suppression circuit at the low-voltage end is connected in series with the resistor to be measured R X between the high voltage end of the JFET switch tube K1 and the source of the JFET switch tube K1, which is used to suppress the resistance to be measured R X High-frequency noise at the high-voltage end.

5. The driving system for suppressing small resistance measurement errors according to claim 4, characterized in that: The low-voltage end high-frequency noise suppression circuit includes a first polarity conversion circuit, a first inductor mutual inductor and a second voltage follower; The first polarity conversion circuit is used to reverse the polarity of the input voltage; The input terminal of the second voltage follower is connected to the resistance to be measured R X The low-voltage end of the first inductor transformer is connected to the same-name end of the secondary side W4, and the opposite-name end of the secondary side W4 is connected to the source of the JFET switch tube K2; The output end of the second voltage follower is connected to the input end of the first polarity conversion circuit. The output end of the first polarity conversion circuit is connected to the same-name end of the primary side W3 of the first inductor transformer. The opposite-name end of the primary side W3 is connected to the power ground.

6. The driving system for suppressing small resistance measurement errors according to claim 4, characterized in that: The high-voltage end high-frequency noise suppression circuit includes a second polarity conversion circuit, a second inductor mutual inductor and a third voltage follower; The second polarity conversion circuit is used to reverse the polarity of the input voltage; The input terminal of the third voltage follower is connected to the resistance to be measured R X The high voltage end of the second inductor transformer is connected to the same-name end of the secondary side W1 of the second inductor transformer, and the opposite-name end of the secondary side W1 is connected to the source of the JFET switch tube K1; The output end of the third voltage follower is connected to the input end of the second polarity conversion circuit. The output end of the second polarity conversion circuit is connected to the same-name end of the primary side W2 of the second inductor transformer. The opposite-name end of the primary side W2 is connected to the power ground.

7. The driving system for suppressing small resistance measurement errors according to claim 1, characterized in that: When the drive system is drawn on the circuit board, a ground ring is used around the JFET switches K1 and K2 for isolation.

8. The driving system for suppressing small resistance measurement errors according to claim 1, characterized in that: Use copper shielded wire and terminal blocks to connect the resistance to be measured R X Connect to JFET switch tubes K1 and K2.

9. The driving system for suppressing small resistance measurement errors according to claim 1, characterized in that: It also includes an amplifier and a high-pass filter; the drain of the JFET switch tube K1 and the drain of the JFET switch tube K2 are both connected to the input end of the amplifier, and the output end of the amplifier is connected to the input end of the high-pass filter.

10. A measurement method implemented by the drive system for suppressing small resistance measurement errors according to claim 9, characterized in that: This measurement method is a high-frequency two-terminal measurement method. Specifically, after closing the analog switch K3, the JFET switch tube K1 is controlled to be turned on and the JFET switch tube K2 is turned off. At this time, the voltage output by the drain of the JFET switch tube K1 is the resistance to be measured R X The high voltage terminal voltage V1 is then controlled to turn off the JFET switch tube K1 and turn on the JFET switch tube K2. At this time, the voltage output by the drain of the JFET switch tube K2 is the resistance to be measured R X The low voltage end V2, calculate the resistance to be measured R X The differential voltage V between the two ends is V1-V2. According to the differential voltage V and the current flowing through the resistor to be measured R X The current I on R X =V / I.

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