A new cryogenic CMOS readout structure for infrared focal plane array

A new current readout structure for the infrared (IR) focal-plane-array (FPA), called the switch-current integration (SCI) structure, is presented in this paper. By applying the share-buffered direct-injection (SBDI) biasing technique and off focal-plane-array (off-FPA) integration capacitor structure, a high-performance readout interface circuit for the IR FPA is realized with a pixel size of 50/spl times/50 /spl mu/m/sup 2/. Moreover, the correlated double sampling (CDS) stage and dynamic discharging output stage are utilized to improve noise and speed performance of the readout structure under low power dissipation. In experimental SCI readout chip has been designed and fabricated in 0.8-/spl mu/m double-poly-double-metal (DPDM) n-well CMOS technology. The measurement results of the fabricated readout chip at 77 K with 4 and 8 V supply voltages have successfully verified both the readout function and the performance improvement. The fabricated chip has a maximum charge capacity of 1.12/spl times/10/sup 8/ electrons, a maximum transimpedance of 1/spl times/10/sup 9/ /spl Omega/, and an active power dissipation of 30 mW. The proposed CMOS SCI structure can be applied to various cryogenic IR FPA's.