On-Chip Fixed-Pattern-Noise Canceling with Non-Destructive Intermediate Readout Circuitry for CMOS Active-Pixel Image Sensors

We propose a new method of canceling the fixed-pattern noise of CMOS activepixel image sensors caused by the threshold mismatch of MOS FETs in pixel circuits. This method uses with non-destructive intermediate readout circuitry. Assuming a TSMC 0.25-μm mixed-signal process, we designed a CMOS image sensor in which the canceling circuit was implemented for each column of the pixel-sensor array. Simulation results revealed that threshold mismatch of O(10−1) V could be reduced to O(10−4) V within a settling time of O(10−7) s.