Ami Semiconductor, Inc.

Semiconductor Components Industries, LLC

Melvin W Stene

James Antone

Brian R Kauffmann

Digital delay locked loops which generate fixed angle delayed (e.g., quadrature) clock signals based on a reference clock signal and that accounts for clock signal delay. The number of quadrature delay elements is calculated based on the number of delay elements needed to provide one or more cycles of delay, and adjusted to reflect system clock delay. The digital delay locked loop also acquires a locked state quickly by sampling more frequently before acquiring the lock than after. Furthermore, jitter is reduced by introducing hysteresis into the sampling process, and by disabling the delay element adjustment process during jitter sensitive times. Lock stability is improved by introducing hysteresis into the lock detection process.

Delay locked loop with low jitter

Delay locked loop with fixed angle de-skew, quick start and low jitter

A delay lock loop circuit is disclosed which includes a delay block which receives the clock signal and delays the clock signal by a selected amount to generate the delayed clock signal. A phase detector receives the clock signal and the delayed clock signal, compares the phases of the two signals and generates a phase comparison signal. A lock detector receives the clock signal and the delayed clock signal, compares the timing of the two signals and generates a potential lock indication signal. A controller receives the phase comparison signal and the potential lock indication signal and provides a delay control signal to the delay block to change the selected delay amount in response to the phase comparison signal. The controller interrupts the clock signal to the delay block for a selected interval in response to the potential lock indication signal, and generates a true lock indication signal in response to the potential lock indication signal after the interruption of the clock signal to the delay block. The delay lock loop circuit is capable of handling a wide range of clock frequencies and a step increase or decrease in the clock frequency.

Growing community of inventors

Pocatello, ID, United States of America

Melvin W Stene