Systems having a phase frequency detector

Abstract

A variety of applications can include a phase frequency detector structured to track the falling edges of two input signals to detect a phase difference between the two signals and to generate one or more signals that can be used to adjust one of the signals with respect to the other when the phase difference is greater than 180 degrees. The phase frequency detector can be implemented in a phase lock loop circuit to track the falling edges of a reference clock signal and the falling edge of a feedback signal. In response to detection of the phase difference between the reference clock signal and the feedback signal being greater than 180 degrees using the falling edges of these signals, the phase frequency detector can adjust its output signals to provide for recovery of a lock condition for the reference clock signal. Additional devices, systems, and methods are discussed.

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