FA-level weak current signal measurement circuit

Abstract

The invention discloses a FA-level weak current signal measurement circuit which comprises a junction field-effect transistor Q1, a sampling resistor R1, a front-stage voltage follower, a same-phase follower circuit, a reverse-phase follower circuit, a reverse-phase adding circuit and a self-biased power supply circuit. According to the measurement circuit, a CMOS (complementary metal-oxide-semiconductor transistor) input operation amplifier serves as a pre-amplifier, the circuit has high input impedance and low input offset current and offset voltage, and measurement capability of the circuit for weak current signals is effectively improved. The self-biased power supply circuit of the measurement circuit can generate one group of power supply voltage related to input signals, so that a power supply traces change of the input signals to change bias, input voltage is constantly positioned at neutral-point potential of a positive power supply and a negative power supply, the operation amplifier operates under the zero-input offset states, so that higher input impedance and lower input offset current are obtained, and the weak current signals are accurately measured.

Description

technical field [0001] The invention relates to the field of current signal measurement, in particular to a femtoampere weak current signal measurement circuit. Background technique [0002] In modern scientific applications, the precise measurement of weak current signals is widely used in fields such as electric field testing, weak light testing, ray detection, aerospace measurement and control, new material research, and semiconductor integrated circuit testing. Taking the field of semiconductor device testing as an example, in the testing applications of semiconductors, sensors and optoelectronic devices, due to the need to measure photocurrent, dark current, leakage current, insulation resistance and corresponding parameters, it is necessary to measure the weak pA level or even fA level Current signals are accurately captured and measured for product characterization. However, when the current signal is in the pA level or even smaller, it becomes very difficult to meas...

AI Technical Summary

Problems solved by technology

However, in the case of measuring weaker current signals (such as fA-level weak currents approaching the measurement limit), effective identification of signals is still not possible, and new methods are still needed to further increase the input impedance and reduce the input bias current

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