A new class of integrated sensors with digital output based upon the use of a flip-flop

Integrated sensors based on flip-flops have been successfully fabricated for the measurement of several physical parameters and subsequently tested. The sensors consist of flip-flops in which one circuit element is sensitive to the desired physical parameter. The sensing action consists of alternately bringing the flip-flop into an unstable and a stable state and counting the resulting ones or zeros. This number is a measure for the asymmetry of the flip-flop and thus for the physical parameter. To illustrate the principle, a force sensor based on a flip-flop containing piezoresistors is presented.