Abstract: A circuit for providing precise delays includes a phase-locked loop driven by a reference frequency source such as a crystal oscillator and including a variable delay circuit. The output of the oscillator is applied to the delay circuit and the non-delayed and delayed signals are compared in a phase comparator. An error signal representative of phase error is developed and applied to vary the amount of delay until the phase error is eliminated. A precise delay referenced to the oscillator frequency is therefore achieved.
Type:
Grant
Filed:
June 3, 1988
Date of Patent:
May 1, 1990
Assignee:
Western Digital Corporation
Inventors:
Karl M. J. Lofgren, Gerald W. Shearer, Kenneth W. Ouyang