A 2D PHOTOSENSOR ARRAY WITH INTEGRATED CHARGE AMPLIFIER

A two-dimensional photosensor array with integrated CMOS charge amplif ier intended for use as a library cell in the implementation of intell igent optical sensors is presented. A single charge amplifier is used to convert the photogenerated charge to a voltage in an array of size n(2). This circumvents the problems of other approaches, in which n se nse amplifiers are pitch-matched with the sensor array and must theref ore be made physically very narrow, a severe constraint on their perfo rmance and often a cause of response non-uniformity. Adequate d.c. gai n 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 mu m triple-metal CMOS t echnology confirm the feasibility of the approach for a 128 x 128-pixe l photodiode array and its applicability to higher-resolution arrays.