A 2-D Photosensor Array with Integrated Charge Amplifier

A two dimensional photosensors array with integrated CMOS charge amplifier intended for use as a library cell in the implementation of intelligent optical sensors is presented. A single charge amplifier is used to covert the photogenerated charge to a voltage in an array of size n2. This circumvents the problems of other approaches, in which n sense amplifiers are pitch-matched with the sensor array and must therefore be made physically very narrow, a severe constraint on their performance and often a cause of response non-uniformity. Adequate DC gain and gain-bandwidth product of the charge amplifier ensure sufficient speed and accuracy for the 8-bit resolution needed in vision systems. Test results on an array fabricated in a 1.2-um-triple-metal CMOS technology confirm the feasibility of the approach for a 128x128-pixel photodiode array and its applicability to higher-resolution array