A very low level optical pulse detection receiver with high dynamic range without AC coupling

A unique event driven receiver has been developed and integrated as part of a signal processing channel for a flyable 512/spl times/512 pixel 3D silicon focal plane array (FPA) module. This paper describes the optical receiver, which is capable of attenuating a low frequency background noise including the l/f noise, while detecting and preserving the target signals. A background subtractor loop is used to keep the reference floor constant, thus enabling the threshold detector to detect the target pulse effectively. Upon detecting a signal (target), the subtractor loop is opened, the background current is memorized and is used to subtract additional incoming background currents. This allows the low frequency portion of the target pulse to be preserved. The preliminary measurements taken from the chip show acceptable performance. More measurements must be taken in order to demonstrate the integrity of the pulse, loop recovery time and drooping, as well as the comparator delay time.