Patent ID: 7129789

Claim:
A fast-locking apparatus for frequency synthesis, comprising: a transition detector receiving a first pulse signal indicative that the phase of an input signal leads the phase of a reference signal, receiving a second pulse signal indicative that the phase of the input signal lags the phase of the reference signal, and generating a state signal indicative of whether a significant transition of the first pulse signal leads a significant transition of the second pulse signal; a first pulse-width detector, responsive to the first pulse signal, generating a first width signal indicative of into which of a plurality of first predefined width ranges the width of the first pulse signal falls; a second pulse-width detector, responsive to the second pulse signal, generating a second width signal indicative of into which of a plurality of second predefined width ranges the width of the second pulse signal falls; and control logic generating a regulation signal used in adjusting the frequency of the input signal according to the state signal and the first and the second width signals.