1 Differential Mode CMOS Active Pixel Sensor (APS) for Optically Programmable Gate Array (OPGA)

A differential mode CMOS active pixel sensor (APS) was designed, fabricated, and tested as part of an optically programmable gate array (OPGA). It was used as a download link between a programmable gate array (PGA) and an optical (holographic) memory, which holds the PGA’s configuration data. A differential light encoding scheme was chosen for representing one-bit data to reduce the bit error rate (BER) and the global variation of the programming beams. The number of photons required to change the state of the detector output was measured. The measured thresholds were 800 photons for green (500nm) and 2500 photons for red (650nm) at a 6 μsec integration time. The test chips were designed and fabricated in a 3.3 Volt, 0.35 μm standard CMOS process technology