Large-dynamic micro-current detection circuit

Abstract

The invention discloses a large-dynamic micro-current detection circuit comprising a leakage discharge switch circuit, a current integral circuit, and a charge discharging and frequency generating circuit. The leakage discharge switch circuit includes a JFET input impedance Q1; a G pole of the Q1 is connected with a non-inverting input terminal of an operational amplifier U2 in the current integral circuit; D and S poles of the Q1 is are in short-circuit connection with left ends of a capacitor C1 and a resistor R1; the right ends of the capacitor C1 and the resistor R1 are connected and thenare connected to a K pole of a diode D1 and a Q2-pin of a dual-D trigger U3 in the charge discharging and frequency generating circuit. The current integral circuit consists of an input buffer circuitformed by connection of an operational amplifier U2 and a follower, an operational amplifier U1 and an integrating capacitor. A COMS dual-D trigger and a peripheral circuit are combined to form a charge absorption circuit and an output frequency generation circuit in the charge discharging and frequency generating circuit. On the basis of the principle, the lower limit of micro-current detectionreaches an order of 10<-12>A; and large-dynamic continuous measurement is realized.

Description

technical field [0001] The invention relates to the technical field of micro electric signal detection, in particular to a large dynamic micro current detection circuit. Background technique [0002] Weak current measurement technology is widely used in nuclear technology, vacuum measurement technology, biomedicine, astronomy, magnetism, geoscience, physics, electrochemistry and other related fields. In many engineering applications, micro-current measurement mainly focuses on 10 -12 A—10 -6 There are two main methods for micro-current measurement suitable for this range: resistance transconductance method and capacitance integration method. [0003] Resistance transconductance method, such as figure 2 Shown Vout=-Iin*R. Limited by amplifier current noise, thermal noise, zero drift, temperature drift, resistance thermal noise, and resistance temperature drift coefficient, when R is a certain value, it can generally meet the measurement of up to 3.5 orders of magnitude. ...

AI Technical Summary

Problems solved by technology

The key difficulty limiting the application of the capacitance integration method lies in the release method of the capacitance charge

There are many ways to realize the automatic release of capacitive charge, but limited by the selection and application method of the discharge switch, the lower limit of measurement is difficult to reach 10 -12 A level, it is also difficult to achieve continuous large dynamic measurement

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