JITTER ATTENUATING DELAY LOCKED LOOP (DLL) USING A REGENERATIVE DELAY LINE

摘要

In general, in one aspect, the disclosure describes a delay locked loop (DLL) with a regenerative delay line that includes a cascade of delay stages. A first delay stage includes a two-input delay device which receives a 180 degree phase shifted signal as feedback. This feedback signal configures the delay line into a regenerative amplifier, the frequency response of which has peaking or resonance at the input frequency which results in jitter filtering. The amount of regeneration is determined by relative strength of an input signal and the feedback signal. Relative strength is determined by relative size of devices receiving the signals. The resonant frequency (with or without oscillations) of the delay line may automatically be tuned to the incoming clock frequency by the DLL control loop. Each of the other delay stages may include two-input delay devices with the inputs shorted for uniformity.