A CMOS 64 # 64 pixel area image sensor chip using Sigma-Delta modulation at each pixel for A#D conversion is described. The image data output is digital. The chip was fabricated using a 1.2#mtwo layer metal single layer poly n-well CMOS process. Each pixel block consists of a phototransistor and 22 MOS transistors. Test results demonstrate a dynamic range potentially greater than 93dB, a signal to noise ratio #SNR# of up to 61dB, and dissipation of less than 1mW with a 5V power supply. 1 Boyd Fowler, Abbas El Gamal, and David X. D. Yang 2 Charge-coupled devices #CCD# are at present the most widely used technology for implementing area image sensors. CCD image sensors have their shortcomings, however. They su#er from low yields, they consume too muchpower #3#, and they are plagued with SNR limitations due to the shifting and detection of analog charge packets, and the fact that data is communicated o# chip in analog form. Several alternatives to CCD area image sensors that use st...