A New Integrated Optical Sensor with Digital Output Based Upon a Flip-flop and an On-chip Photodiode

This paper presents a new light intensity sensor with digital output, a high sensitivity and a rather simple circuit configuration. The sensor is based upon bringing a flip-flop, in which an on-chip silicon photodiode is incorporated, alternately into an unstable and a stable state and counting the resulting ones or zeros. This number is a measure for the light intensity. The measurement range is increased by adding a triangle wave to the flip-flop.