Gated multi-cycle integrator (GMCI): a readout circuit for repetitive imaging of FPA

摘要

A gated multi-cycle integrator (GMCI) is presented to recover weak repetitive image signal from strong background. The GMCI could operate in several modes such as Capacitive-transimpedance amplifier (CTIA), gated integration (GI) and background-cancellation integration (BCI). When GMCI operates at BCI mode, the storage well of a pixel is mainly used for signal integration even there exists strong background or large dark current. Thus the signal-to-noise ratio (SNR), the dynamic range and the sensitivity of detection are greatly improved. In addition, the transmission windows of BCI peak at odd harmonics of the modulation frequency. Therefore the detector's 1/f and other low frequency noises can be attenuated. A switched capacitor integrator (SCI) was designed to carry out the performance of GMCI. The switch induced fixed pattern can be obliterated by taking the differential of two multi-cycle integrated signals with 180° phase difference. Preliminary chip test shows that the GMCI can read out modulated signal that is five orders less than the background.