Driving system and measuring method for inhibiting measurement error of micro resistor

Abstract

The invention discloses a driving system and a measuring method for inhibiting micro resistance measuring errors, and belongs to the field of precision measurement. The problem that a driving system for measuring the micro resistance is difficult to suppress low-frequency noise and cannot measure the micro resistance at high precision is solved. The driving system is used for converting low-frequency voltage signals of the high-voltage end and the low-voltage end of a resistor to be measured into high-frequency voltage signals, the driving system is constructed through JFET switch tubes K1 and K2, and a transient compensation circuit is used for restraining transient voltage of the JFET switch tube K1. The switching tube driving circuit is used as a feedback loop to ensure that the gate-source voltage of the JFET switching tubes K1 and K2 is zero, and mutation caused by noise is suppressed. The device and the method are mainly used for high-precision micro resistance measurement.

Description

Technical Field

[0001] The 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 basic physical quantity in electricity, whether resistance can be accurately measured plays an extremely important role in scientific research, production and equipment development. The measurement of resistance indirectly affects the development of high-end equipment. The implementation of many new technologies also requires precise measurement of resistance. For example, in the field of temperature measurement, the most widely used temperature sensor is the platinum resistor, which mainly uses its different resistance values ​​at different temperatures, and has the advantages of high stability, high precision and linearity close to a straight line in the medium temperature range (-200 ~ 650℃). Therefore, most of the high-precision thermometers used in the market are realized by high-precision measurement of the resistance value of the platinum resistor.

[0003] In recent years, certain achievements have been made in the high-precision measurement of tiny resistors. However, in the face of the increasing demand for precision, the measurement of tiny resistors is still a challenging topic. The typical method of measuring resistance is to apply a current to the resistor to be measured, read the voltage across the resistor to be measured, and then find the resistance value. When measuring tiny resistors, if a large current is used to flow into the tiny resistor, the voltage across the resistor may be too large, so that the oxide layer on the surface of the small resistor is broken down, making the measured resistance value smaller than the actual value, and it will also cause damage to the resistor to be measured that is difficult to repair. Even if it is not broken down, a large current flows through the resistor for a long time, and the temperature changes on the resistor, thereby changing the resistance value. Therefore, in order to accurately measure small resistors, it is necessary to apply a small current to the resistor to be measured. However, when a small current flows through the resistor to be measured, the voltage generated is very small. If you want to accurately measure it, you need to suppress various errors. Especially when the resistance of the resistor to be measured is less than 1Ω, errors such as thermoelectric potential and wire resistance will cause great error interference to the measurement, resulting in a large difference between the measurement result and the actual result. Therefore, it is necessary to design a suitable measurement drive system to suppress the error, thereby improving the measurement accuracy.

[0004] The traditional driving system for suppressing the measurement error of micro resistors has the problem of being unable to filter out low-frequency noise, so it is difficult to improve the measurement accuracy. Micro resistors generally refer to resistors with a resistance value of less than 1Ω. At present, the driving system for measuring micro resistors mainly adopts four-wire wiring and bias voltage compensation method to suppress the wire resistance and thermoelectric potential. For other errors, the filtering circuit is mainly used to filter out. This method improves the measurement accuracy to a certain extent, but the current highest accuracy is mΩ level, which is difficult to meet the needs of high-precision measurement. The main reason is that the filtering circuit can effectively filter out the noise with a large difference from the signal frequency, but it is difficult to filter out the error with a similar signal frequency. Among them, the error with the greatest impact is low-frequency noise, which is mainly 1 / f noise and temperature drift. Therefore, in order to improve the measurement accuracy and meet the measurement accuracy requirement of the equipment with a maximum uncertainty of 0.009% in the range of 0-1Ω, it is necessary to suppress the low-frequency noise. Therefore, it is necessary to study a driving circuit that suppresses the measurement error of micro resistors to meet the needs of high-precision measurement of micro resistors. Summary of the invention

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

[0006] A drive system for suppressing small resistance measurement errors, the drive system is used to measure the resistance R X The low-frequency voltage signal at the high and low voltage ends is converted into a high-frequency voltage signal, and its driving system includes a constant current source, a transient compensation circuit, a switch tube driving circuit, a first voltage follower, an analog switch K 3 、JFET switch tube K 1 and K 2 ;

[0007] The constant current source output is 10mA; the JFET switch tube K 1 and K 2 Asynchronous operation; transient compensation circuit is used to suppress the JFET switch tube K 1 The transient voltage;

[0008] The constant current source is connected through the analog switch K 3 With the resistance to be measured R X The high voltage end is connected to the resistance to be measured R X The high voltage end of the JFET switch tube K 1 The source of the JFET switch tube K is connected to the first input and output terminal of the transient compensation circuit. 1 The drain of the transient compensation circuit is connected to the second input and output terminal, the input terminal of the first voltage follower and the JFET switch tube K 2The drain of the first voltage follower is connected at the same time, and the output of the high-pass filter is used as the output of the driving system; the output end of the first voltage follower is connected to the reference voltage input end of the transient compensation circuit and the feedback input end of the switch tube driving circuit at the same time;

[0009] The first and second control output terminals of the switch tube driving circuit are respectively connected to the JFET switch tube K 1 and K 2 The gate connection;

[0010] Resistance to be measured R X The low voltage end of the JFET switch tube K 2 After the source of the JFET is connected, it is connected to the power ground; 1 The drain and JFET switch tube K 2 The drain electrodes serve as the output terminals of the driving system to output high-frequency voltage signals.

[0011] Preferably, the switch tube driving circuit includes a resistor R 1 To R 4 and two gate drivers;

[0012] The driving signal output terminal of the first gate driver is connected to the resistor R 1 One end and resistor R 2 At the same time, the resistor R 1 The other end of the switch tube driving circuit is used as the first output end;

[0013] The driving signal output terminal of the second gate driver is connected to the resistor R 3 One end and resistor R 4 At the same time, the resistor R 4 The other end is used as the second output end of the switch tube driving circuit;

[0014] Resistor R 2 The other end and resistor R 3 After the other end is connected, it serves 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, a resistor R 5 To R 6 , and capacitor C 1 To C 2 ;

[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 the resistor R 5 One end and resistor R 6One end of the resistor R 5 The other end of the capacitor C 1 One end of the capacitor C 1 The other end of the transient compensation circuit serves as the first input and output end;

[0018] Resistor R 6 The other end of the capacitor C 2 One end of the capacitor C 2 The other end serves as the second input and output end of the transient compensation circuit.

[0019] Preferably, the driving system for suppressing small resistance measurement errors further includes high- and low-voltage end high-frequency noise suppression circuits; wherein the low-voltage end high-frequency noise suppression circuit is connected in series to the resistance to be measured R X The low voltage end of the JFET switch tube K 2 between the source and the measured resistance R X The high-frequency noise suppression circuit at the low-voltage end is connected in series with the resistor R X The high voltage end of the JFET switch tube K 1 between the source and the measured resistance 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 and the secondary side W of the first inductor transformer 4 The same-named ends of the secondary side are connected at the same time, 4 The opposite end of the JFET switch tube K 2 The source connection of

[0023] The output end of the second voltage follower is connected to the input end of the first polarity conversion circuit, and the output end of the first polarity conversion circuit is connected to the primary side W of the first inductor transformer. 3 The same-name end of the original edge W 3 The opposite end 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 RX The high voltage end and the secondary side W of the second inductor transformer 1 The same-named ends of the secondary side are connected at the same time. 1 The opposite end of the JFET switch tube K 1 The source connection of

[0027] The output end of the third voltage follower is connected to the input end of the second polarity conversion circuit, and the output end of the second polarity conversion circuit is connected to the primary side W of the second inductor transformer. 2 The same-name end of the original edge W 2 The opposite end is connected to the power ground.

[0028] Preferably, when the drive system is drawn on the circuit board, the JFET switch tube K 1 and K 2 Use a ground ring around it for isolation.

[0029] Preferably, the resistance to be measured R is connected by copper shielded wires and wiring terminals. X With JFET switch tube K 1 and K 2 to connect.

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

[0031] JFET switch tube K 1 The drain and JFET switch tube K 2 The drains of the transistors are connected to the input of the amplifier, and the output of the amplifier is connected to the input of the high-pass filter.

[0032] The measurement method implemented by the driving system for suppressing the small resistance measurement error is a high-frequency two-terminal measurement method, specifically: closing the analog switch K 3 After that, control the JFET switch tube K 1 Conducting, JFET switch tube K 2 Turn off, at this time the JFET switch tube K 1 The voltage of the drain output is the resistance to be measured R X The high voltage terminal voltage V 1 ; Then control the JFET switch tube K 1 Turn off, JFET switch tube K 2 The JFET switch tube K 2 The voltage of the drain output is the resistance to be measured R X The low voltage end V 2 , calculate the resistance to be measured R X The differential voltage across the two ends is V = V 1 -V 2 , according to the differential voltage V and the current flowing through the resistor to be measured RX The current I on R X＝ V / I.

[0033] Advantages of the present invention:

[0034] After analyzing the error in measuring tiny resistors, it is found that the main factor affecting the measurement accuracy is 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 measuring method for suppressing the error in measuring tiny resistors, and the driving system 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 process of converting the low-frequency voltage signals into high-frequency voltage signals is to separate the useful signal and the low-frequency noise in frequency, so the subsequent high-pass filtering can filter the low-frequency noise of the low-frequency voltage signal well, effectively suppress the low-frequency noise, and when the constant current source outputs a constant 10mA current, the requirement of high-precision measurement of tiny resistors is met.

[0035] Since the resistance to be measured R X The input is a small resistor, and the voltage generated by a constant 10mA current flowing through the small 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. 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 adopts a JFET switch tube K 1 and K 2 The drive system is specially designed to effectively avoid non-periodic fluctuations of the signal, 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 driving circuit is used as a feedback loop to ensure that the JFET switch tube K 1 and K 2 The gate-source voltage is zero. When the JFET switch is 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 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 fast switching speed. Due to the existence of its parasitic capacitance, there will be voltage overshoot in the switching transient. The overshoot will not only increase the possibility of damaging the device, but also introduce high-frequency noise. Therefore, a transient compensation circuit is added to eliminate the JFET switch tube K 1 Transient voltage overshoot is reduced, thereby suppressing the interference caused by switching transients. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a 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 be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are 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: The following is combined Figure 1 The present embodiment is described. The driving system for suppressing the error of measuring a small resistance in the present embodiment is used to measure the resistance R X The low-frequency voltage signal at the high and low voltage ends is converted into a high-frequency voltage signal, and its driving system includes a constant current source, a transient compensation circuit, a switch tube driving circuit, a first voltage follower, an analog switch K 3 、JFET switch tube K 1 and K 2 ;

[0043] The constant current source output is 10mA; the JFET switch tube K 1 and K 2 Asynchronous operation; transient compensation circuit is used to suppress the JFET switch tube K 1 The transient voltage;

[0044] The constant current source is connected through the analog switch K 3 With the resistance to be measured R X The high voltage end is connected to the resistance to be measured R X The high voltage end of the JFET switch tube K 1 The source of the JFET switch tube K is connected to the first input and output terminal of the transient compensation circuit. 1 The drain of the transient compensation circuit is connected to the second input and output terminal, the input terminal of the first voltage follower and the JFET switch tube K 2 The drain of the first voltage follower is connected at the same time, and the output of the high-pass filter is used as the output of the driving system; the output end of the first voltage follower is connected to the reference voltage input end of the transient compensation circuit and the feedback input end of the switch tube driving circuit at the same time;

[0045] The first and second control output terminals of the switch tube driving circuit are respectively connected to the JFET switch tube K 1 and K 2 The gate connection;

[0046] Resistance to be measured R X The low voltage end of the JFET switch tube K 2 After the source of the JFET is connected, it is connected to the power ground; 1 The drain and JFET switch tube K 2 The drain electrodes serve as the output terminals of the driving system to output high-frequency voltage signals.

[0047] The present invention provides a driving system and a measuring method for suppressing the measurement error of a small resistance. The driving system is used for converting 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 signals into high-frequency voltage signals is to separate the useful signals from the low-frequency noise. Therefore, 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 of high-precision measurement of the small resistance is met.

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

[0049] The analog switch K 3 Used to control whether to apply current value to the resistance to be measured. When the current I flows through the resistance 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 Rx to be measured is a tiny 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, and 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 tiny signal transmission process, the present invention selects 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, it is very small, which is very suitable for the transmission of tiny signals, effectively avoiding the signal non-periodic fluctuation, 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 JFET switch tube K 1 and K 2 The gate-source voltage is zero. When the JFET switch is 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 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 fast switching speed. Due to the existence of its parasitic capacitance, there will be voltage overshoot in the switching transient. The overshoot will not only increase the possibility of damaging the device, but also introduce high-frequency noise. Therefore, a transient compensation circuit is added to eliminate the JFET switch tube K 1 Transient voltage overshoot is reduced, thereby suppressing the interference caused by switching transients.

[0053] 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 JFET switch tube K 1 and K 2 The gate-source voltage is zero. When the JFET switch is 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 is turned on, but also prevents voltage mutations to a certain extent and suppresses mutations caused by noise. Specifically, the specific structure of the switch drive circuit is:

[0054] See also Figure 1 , the switch tube driving circuit includes a resistor R 1 To R 4 and two gate drivers;

[0055] The driving signal output terminal of the first gate driver is connected to the resistor R 1 One end and resistor R 2 At the same time, the resistor R 1 The other end of the switch tube driving circuit is used as the first output end;

[0056] The driving signal output terminal of the second gate driver is connected to the resistor R 3 One end and resistor R 4 At the same time, the resistor R 4 The other end is used as the second output end of the switch tube driving circuit;

[0057] Resistor R 2 The other end and resistor R 3 After the other end is connected, it serves 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, a resistor R5 To R 6 , and capacitor C 1 To C 2 ;

[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 the resistor R 5 One end and resistor R 6 One end of the resistor R 5 The other end of the capacitor C 1 One end of the capacitor C 1 The other end of the resistor R 6 The other end of the capacitor C 2 One end of the capacitor C 2 The other end serves as the second input and output end of the transient compensation circuit.

[0061] In the preferred embodiment, the JFET switch tube is used as a high-frequency switching device. Its switching speed is too fast. Due to the existence of its parasitic capacitance, there will be voltage overshoot in the switching transient. The overshoot will not only increase the possibility of damaging the device, but also introduce high-frequency noise. Therefore, a transient compensation circuit is added to eliminate the JFET switch tube K 1 Specifically, in normal working state, the capacitor will not interfere with the circuit due to the DC isolation effect, but at the moment of turning on or off, the negative voltage output by the D / A converter will compensate for it, thereby eliminating the voltage overshoot of the switching transient and suppressing the interference caused by the switching transient.

[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 The low voltage end of the JFET switch tube K 2 between the source and the measured resistance R X High-frequency noise at the low-voltage end;

[0064] The high-frequency noise suppression circuit at the high-voltage end is connected in series with the resistor to be measured R X The high voltage end of the JFET switch tube K 1 between the source and the measured resistance 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 and the secondary side W of the first inductor transformer 4 The same-named ends of the secondary side are connected at the same time, 4 The opposite end of the JFET switch tube K 2 The source connection of

[0068] The output end of the second voltage follower is connected to the input end of the first polarity conversion circuit, and the output end of the first polarity conversion circuit is connected to the primary side W of the first inductor transformer. 3 The same-name end of the original edge W 3 The opposite end 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 and the secondary side W of the second inductor transformer 1 The same-named ends of the secondary side are connected at the same time, 1 The opposite end of the JFET switch tube K 1 The source connection of

[0072] The output end of the third voltage follower is connected to the input end of the second polarity conversion circuit, and the output end of the second polarity conversion circuit is connected to the primary side W of the second inductor transformer. 2 The same-name end of the original edge W 2 The opposite end is connected to the power ground.

[0073] In this preferred embodiment, an inductor transformer W is added at the input end. 1 ~W 4 The compensation will not affect the DC signal, but the high-frequency noise will be collected by the voltage follower. After the polarity conversion circuit, the voltage changes from positive voltage to negative voltage. Since it is high-frequency noise, it can be detected by the W 2 Coupling to W 1The input channel can eliminate the high-frequency noise caused by the current loop. That is, the two inductance 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. 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 the circuit board, the JFET switch tube K 1 and K 2 A ground ring is used around the JFET to isolate high-frequency noise. 1 and K 2 During the measurement process, the device needs to be frequently turned on and off, so it is easy to introduce high-frequency noise. Using a ground loop for isolation can greatly avoid 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 wiring terminals to connect the resistance to be measured R X With JFET switch tube K 1 and K 2 It has the effect of isolating 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; a JFET switch tube K 1 The drain and JFET switch tube K 2 The drains of the transistors are connected to the input of the amplifier, and the output of the amplifier is connected to the input of the high-pass filter.

[0077] In this preferred embodiment, an amplifier and a high-pass filter are added to the JFET switch tube K 1 and K 2 The output high-frequency voltage signal is amplified and filtered. Since the high-pass filter has an attenuation effect on the signal, if it is directly filtered, it may further attenuate the tiny signal and affect the measurement result. 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 the quality of the signal while filtering out the low-frequency signal.

[0078] Specific implementation method 2: A measurement method implemented by the driving system for suppressing the measurement error of small resistance is a high-frequency two-terminal measurement method, specifically: closing the analog switch K 3 After that, control the JFET switch tube K 1 Conducting, JFET switch tube K 2Turn off, at this time the JFET switch tube K 1 The voltage of the drain output is the resistance to be measured R X The high voltage terminal voltage V 1 ; Then control the JFET switch tube K 1 Turn off, JFET switch tube K 2 The JFET switch tube K 2 The voltage of the drain output is the resistance to be measured R X The low voltage end V 2 , calculate the resistance to be measured R X The differential voltage across the two ends is V = V 1 -V 2 , 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 tiny differential mode signal input to the resistor to be measured, so that in one measurement cycle, half of the cycle is the high-voltage terminal voltage of the resistor to be measured, and half of the cycle is the low-voltage terminal voltage of the resistor to be measured. The difference can be calculated later to obtain the differential voltage across the resistor to be measured; 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 examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in 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 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 a current of 10mA; the JFET switch tubes K1 and K2 work asynchronously; the transient compensation circuit is used to suppress the transient voltage of the JFET switch tube 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-output end of the transient compensation circuit, the drain of the JFET switch tube K1 is simultaneously connected to the second input-output end of the transient compensation circuit, the input end of the first voltage follower and the drain of the JFET switch tube K2, and the output of the high-pass filter is used 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; Resistance to be measured R X The low voltage end is connected to the source of the JFET switch tube K2 and then connected 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 a 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 simultaneously 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, 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 the 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: The high-voltage and low-voltage high-frequency noise suppression circuits are also included; 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 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 of the first inductor transformer, 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, and 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, and 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 switch tubes 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 R X Connected 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: The 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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