Weak current integrating circuit based on correlated double sampling and electrostatic protection and protection method

Abstract

The invention discloses a weak current integrating circuit based on correlated double sampling and electrostatic protection and a protection method. The weak current integrating circuit comprises an electrostatic protection circuit and a correlated double-sampling circuit. Firstly, in a zero clearing stage, capacitors in a circuit are connected with reset level signals, and all the capacitors arereset; secondly, offset and low-frequency noise information of an amplifier is stored by using an offset storage capacitor in a self-zeroing stage; at the amplification stage, the current is sent to the amplifier through a closed sampling switch to amplify the signal. The electrostatic protection circuit is adopted to protect an internal circuit from electrostatic interference; the correlated double-sampling circuit converts an input current signal into a voltage on a sampling capacitor, the offset and low-frequency noise information of the amplifier is stored through the offset storage capacitor, and meanwhile, a switch in the circuit adopts a low-leakage-current switch structure such that the sampling frequency is reduced, and the lower current resolution and lower operational amplifiernoise are obtained.

Description

technical field [0001] The invention relates to a weak current integration circuit and a protection method based on correlated double sampling and electrostatic protection, and belongs to the field of integrated circuits. Background technique [0002] In semiconductor measurement, it is often necessary to measure the weak current of μA~pA level. The weak current is relative to the noise. The weak current is very easy to be disturbed by noise and static electricity during the detection process. Part of the source of noise comes from the influence of external noise, and part of it comes from low-frequency noise such as the offset of the circuit itself and 1 / f noise. [0003] The correlated double-sampling circuit charges and discharges the sampling capacitor through two stages of reset and integration, and obtains the difference between the signal level and the reset level, breaking the time correlation of 1 / f noise, but the switching capacitor is closed and disconnected At t...

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Problems solved by technology

[0003] The correlated double-sampling circuit charges and discharges the sampling capacitor through two stages of reset and integration, and obtains the difference between the signal level and the reset level, breaking the time correlation of 1 / f noise, but the switching capacitor is closed and disconnected At the same time, it will bring the impact of charge injection, causing charge changes between capacitors, introducing unnecessary KT / C noise and offset

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