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...

The proliferation of digital computing and signal processing in electronic systems is often described as "the world is becoming more digital every day."