Wide-range high-precision micro-current measurement system and method

Abstract

The invention relates to a wide-range high-precision micro current measurement system and method. The system comprises a multiple root signal converter, an analog-to-digital conversion circuit and a microprocessor circuit, wherein the multiple root signal converter comprises a logarithmic transformation circuit, an adder and an exponential transformation circuit; the logarithmic transformation circuit receives a to-be-measured micro current signal and a reference current signal, and logarithmic transformation is carried out respectively to output two voltage signals to the adder; the adder sums up the voltage signals and the sum is transmitted to the exponential transformation circuit; the exponential transformation circuit receives the sum and carries out exponential transformation, and an analog voltage signal is outputted to the analog-to-digital conversion circuit; the analog-to-digital conversion circuit receives the analog voltage signal, converts the analog voltage signal to a digital signal and transmits the digital signal to the microprocessor circuit; and the microprocessor circuit receives the digital signal, multiple square operation is carried out to restore the valueof a to-be-measured current signal, and current measurement is completed. High measurement precision is achieved in a whole range.

Description

technical field [0001] The invention relates to a micro-current measurement system and method, in particular to a wide-range and high-precision micro-current measurement system and method, which can be applied to the detection field of ion current, photocurrent and other weak currents in various instruments and equipment. Background technique [0002] In instrument measurement, it is often necessary to detect various current signals, such as the current of ion fragments bombarded by the ionization source of a mass spectrometer, the ionization current of a gas chromatograph hydrogen flame, the total ion current converted from vacuum by an ionization vacuum gauge, and weak light signals The generated photocurrent and so on, these current signals are often ranging from "fA" level to "mA" level, not only require extremely weak current detection capability, but also require sufficient measurement resolution in a relatively wide measurement range, so The wide-range weak current me...

AI Technical Summary

Problems solved by technology

The general method is to use a pair of tubes made on the same chip to offset the reverse saturation current Is of the middle PN junction, and use a thermistor to compensate the thermal voltage VT, but it is difficult for the thermistor to make the most appropriate compensation in a wide range. Moreover, it is troublesome to choose and match, even if high-precision integrated circuits are used, they will be affected by these factors

In addition, the logarithmic compression method is used, the small signal changes too drastically, and the large signal is compressed very severely. It is difficult to obtain more effective digits in the entire measurement range, especially the large signal part.

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