An event-detection high dynamic range CMOS image sensor
A novel CMOS image sensor is proposed to overcome the analog design limitations in Active Pixel Sensors - APS and large area overcome in Digital Pixel Sensors - DPS for use in bio-medical applications. The design includes a pixel level event generation mechanism by using a binary search technique. A ramp voltage generated by a combined block of 10-bit counter and DAC Digital to Analog Converter is compared with the pixel integrated voltage at each clock cycle at the same time allowing a fixed exposure time interval. The proposed design arrives to a total pixel array area of 1505.62μm × 4566μm for a pixel array size of 160(Zf) × 120(V). The photo-active area in each pixel is considered as the N-well area in a p002B;/n-well/p-sub type photo-transistor corresponding to a size of 11.24μm × 10.76μm. The overall pixel array reaches a fill factor of %34.