CMOS READOUT ARCHITECTURE AND METHOD FOR PHOTON-COUNTING ARRAYS

摘要

Embodiments of the present invention include complementary metal-oxide- semiconductor (CMOS) readout architectures for photon-counting arrays with a photon-counting detector, a digital counter, and an overflow bit in each of the sensing elements in the array. Typically, the photon-counting detector is a Geiger- mode avalanche photodiode (APD) that emits brief pulses every time it detects a photon. The pulse increments the digital counters, which, in turn, sets the overflow bit once it reaches a given count. A rolling readout system operably coupled to each sensing element polls the overflow bit, and, if the overflow bit is high, initiates a data transfer from the overflow bit to a frame store. Compared to other photo- counting imagers, photon-counting imagers with counters and overflow bits operate with decreased transfer bandwidth, high dynamic range, and fine spatial resolution.