US Patent 7279995 Circuit for controlling the time duration of a signal

A circuit controls the pulse width of an output signal from a voltage controlled oscillator. The voltage controlled oscillator includes a ring oscillator comprising a plurality of series-connected inverters. In one embodiment a selector selects at least one output signal from an inverter in the plurality of series-connected inverters. An output circuit receives the selected output signal and a reference signal to provide a final output signal having a time duration proportional to the number of inverters between the inverters providing the reference signal and the output signal to the selection circuit.