Advances in on-focal-plane A/D with low-power optical readout

Abstract

Development of per pixel analog to digital conversion technology for staring focal plane arrays has resulted in improvements in well capacity, power consumption, linearity and signal to noise performance compared to present analog readout approaches. This new digital approach has also allowed the application of alternative on focal readout approaches. These include passive optical devices for readout as well as current mode switching wired output. Test results and design considerations of a recently completed 128 X 128 staring array are presented. The design was based on MOSAD, Multiplexed OverSample A/D, which places a filtering A/D modulator at each pixel. This readout has been linked on focal plane to passive reflective optical modulators providing high data rate digital outputs as an alternative to wired interconnect. A comparative study of current mode wired switching verses optical mode readout was completed. These results will also be presented. Both the optical readout and focal plane array designs were developed with funding from the U.S. Army Night Vision and Electronic Sensors Directorate.