US Patent 7173470 Clock sources and methods with reduced clock jitter

Clock sources are provided which are especially useful for reducing phase noise in signal samplers that typically provide samples of an analog input signal in signal-conditioning systems such as analog-to-digital converters. This phase noise reduction is realized with the recognition that sampler noise is related to clock jitter by a ratio of the input signal's slew rate to the clock's slew rate. Clock embodiments include a frequency divider and a signal gate. The divider divides a first signal to provide a second signal with a slew rate lowered from the slew rate of the first signal and the gate passes the second signal when commanded by the first signal to thereby generate a clock signal.