Digital display high-sensitivity conductivity and high-resistance resistivity measuring circuit and method

Abstract

The invention discloses a digital display high-sensitivity conductivity and high-resistance resistivity measuring circuit which comprises a measuring circuit body, a precise amplifying and convertingcircuit and a digital A / D converting and displaying circuit in sequential connection. The measuring circuit body sends voltage signals of a measured resistor to the precise amplifying and converting circuit, and the voltage signals are adjusted to voltages for ratio method resistivity measurement after being subjected to impedance conversion and resistivity partial pressure by the precise amplifying and converting circuit. The precise amplifying and converting circuit sends adjusted reference voltages and adjusted measurement signal voltages to the digital A / D converting and displaying circuit, and the reference voltages and the signal voltages are converted into corresponding display values by the digital A / D converting and displaying circuit to be displayed. The invention further provides a digital display high-sensitivity conductivity and high-resistance resistivity measuring method. When the to-be-measured Rx changes according to the coefficient k, the measurement signal voltages / reference voltages can change in inversion proportion according to the same change coefficient k, and therefore conductivity measurement is realized, calculation errors in the prior art can be eliminated, and the measurement precision is high.

Description

technical field [0001] The invention relates to the field of electronic technology, in particular to a conductance and high-value resistance measuring circuit, and a method for measuring conductance and high-value resistance in a pure resistance circuit by using the circuit, especially a method for measuring ultra-high-value resistance. Background technique [0002] At present, the super-high-value resistance measured by conductance conversion in the market can only measure 0.1nS, which is 10000MΩ when converted into resistance. For example, digital meters such as models DF930F+ and VC9807A+ have an accuracy of ±1.0%. It cannot be applied to occasions where higher resistance values ​​are measured. [0003] It can be seen from the published DF930F conductance measurement circuit diagram that the measurement circuit uses a 3.2V power supply voltage, a 100k resistor, a 30k resistor, and a reference voltage of 1.0V. After connecting to a standard resistor of 10MΩ, adjust the pot...

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Problems solved by technology

Generally, only a high resistance of 20MΩ can be measured, and the standard resistance is 10MΩ. If it is higher, the current flowing through the standard resistance and the resistance under test will be too weak, which will easily introduce external interference, resulting in unstable low-level jumps, and also Because the input interface of the A / D converter has an RC input circuit filter, when the resistance values ​​of the standard resistance and the measured resistance are too large, the time constant of the RC input circuit filter will be too large, causing the measurement time to be too long and impractical. significance

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