Single-shot circuit having process independent duty cycle

Abstract

A single-shot circuit is fabricated as an integrated circuit except for a single capacitor requiring a single pin to connect to the on-chip circuitry. The single-shot is rendered independent of process variations and operating conditions by incorporating an analog feedback loop. The output of the single shot is detected by an analog circuit which includes a positive and negative voltage generator the ratio of whose voltages is a function of the desired duty cycle. The generators are actuated, respectively, when a pulse exists and when there is no pulse. The analog feedback circuit also includes an integrator for receiving and integrating the positive and negative voltages from the generators. The integrated and amplified voltages are fed back to the last stage of the single-shot circuit. When the duty cycle is high, the voltage that is fed back drives the single shot circuit to reduce the pulse width. When the duty cycle is low, the voltage that is fed back drives the single-shot circuit to increase the pulse width. Thus, the pulse width of the single shot is controlled by the built-in values of the positive and negative voltage generators and is independent of process variations and operating conditions.