A new CMOS readout circuit for uncooled bolometric infrared focal plane arrays

By incorporating the basic constant current (CC) configuration with the buffered direct injection (BDI) structure, a new readout circuit called the constant current buffered direct injection (CCBDI) is proposed for the uncooled bolometer detector FPAs. Due to the use of BDI structure, the offset is decreased and the linearity range is increased. Thus linearity, dynamic range, and uniformity are improved. An experimental chip of 64×64 CCBDI FPA readout circuit has be designed and fabricated by using 0.5 μm double-poly double-metal n-well CMOS technology with the cell size of 50×50 μm² . The measured linearity is 94.36% whereas the measured uniformity is 81.3%. Both measurement and simulation results have verified the advantageous features of the proposed CCBDI readout circuit. It is believed that the new CCBDI structure has a great potential in the applications of large uncooled bolometer FPAs