Array of sensors with A/D conversion based on flip-flops

An array of silicon light intensity sensors is described. Switched bias flip-flops are used to obtain a digital output. The flip-flops contain bipolar transistors which are sensitive to illumination. A triangle-wave voltage is used for analog-to-digital conversion. An analysis of the resolution of the measurement technique when it is used for low-signal level high-resolution measurement is presented. Experimental results for optical flip-flop sensor arrays based on phototransistors, fabricated in the bipolar process, are presented. The devices contain 64 flip-flop sensors organized in 8×8 arrays. Each flip-flop sensor consists of two resistors and two phototransistors, of which one is covered by aluminum