High-sensitivity digital nanovoltmeter and realization method thereof

Abstract

The invention relates to a high-sensitivity digital nanovoltmeter and a realization method thereof. A conversion galvanometer for converting current into deflection laser and a feedback resistance network for voltage division are arranged on a measuring loop; a CCD circuit receives light-spot images of the conversion galvanometer, then the light-spot images are inputted to a CPU circuit to be processed, and the CPU circuit obtains the positions of light dots through filtering and calculation; the CPU circuit simultaneously controls a D / A converter to output a direct-current voltage; when the direct-current voltage passes through a voltage of the feedback resistance network after voltage division to offset a measured voltage, a current in the measuring loop is zero, the light spots in the light-spot images outputted by the CCD circuit are positioned at original points, and the CPU circuit outputs the direct-current voltage outputted by the D / A converter as a detected voltage to be measured; because the measuring loop, a feedback circuit and a detection circuit are completely-independent electric systems, and the circuits are only connected by optical signals, the high-sensitivity digital nanovoltmeter has the strong common-mode interference resistant capability and can be used as a high-sensitivity zero-pointing instrument to be applied to high-accuracy measuring equipment suchas potential difference meters and electrical bridges.

Description

technical field [0001] The invention relates to a low-voltage current detection device, in particular to a high-sensitivity digital nanovoltmeter which can be used for direct current low-voltage measurement and voltage zero pointing and its realization method. Background technique [0002] Weak current monitoring and detection technology is widely used in the fields of precise measurement of weak signals, bioelectrical current detection, semiconductor and chemical analysis. At present, the instruments used for high-precision DC low-voltage measurement and voltage zero mainly include magnetoelectric galvanometers, photoelectric amplification galvanometers, and digital nanovoltmeters. Among them, both the magnetoelectric system galvanometer and the photoelectric amplification galvanometer adopt light point display. Due to the influence of factors such as the earthquake, the Brownian motion of air molecules near the moving frame of the galvanometer, and the thermal noise voltag...

AI Technical Summary

Problems solved by technology

However, the electronic amplifier of the digital nanovoltmeter adopts modulation and demodulation technology and active amplification technology, so there are defects such as large noise and small adaptation range of source impedance, and the anti-common-mode interference ability is lower than that of the photoelectric galvanometer.

Digital nanovoltmeters cannot be used instead of photoelectric amplifying galvanometers in high-precision measuring equipment such as potentiometers and electric bridges due to their own defects that cannot meet the high-precision measurement requirements.

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