A TDI CMOS Readout Circuit for IRFPA with Linearity Improvement

This paper presents a readout integrated circuit (ROIC) for infrared focal plane array (IRFPA) with time delay and integration (TDI) mode suitable for CMOS technology. The unit-cell input stage is implemented with switch current integration (SCI) structure with a simple linearity improvement circuit. The current flowing out of the unit-cell is directed to the off-pixel integration capacitors through a switch array. The signals from different detectors for the same image pixel are stored on the same capacitor, implementing the summation function. The voltage signals on capacitors are read out serially after they pass through the correlated double sample stage. Defective pixel correction is also implemented in this circuit. The simulation results show that the TDI function is correctly implemented and the linearity is improved from 96.15% to 97.70% (without the common output stage) at the expense of a little increase of power dissipation.