Patent ID: 6351508
Filing Date: 2002-02-26
Classification: H03L,H04J

Abstract:
A phase/frequency detector circuit for use with an oscillator controller to cause the oscillator to generate a controlled signal having a phase and frequency which is closely related to a reference signal, said circuit comprising:a) first means responsive to the reference signal for producing a first intermediate output corresponding to the reference signal; b) second means responsive to the controlled signal for producing a second intermediate output corresponding to the controlled signal; c) third means responsive to said first and second intermediate outputs for producing an oscillator control signal, said third means includes an exclusive NOR (XNOR) having a first input coupled to said first intermediate output and a second input coupled to said second intermediate output; and d) fourth means responsive to a change in frequency of the reference signal, said fourth means coupled to said first and second means, wherein said oscillator control signal has a duty cycle which corresponds to the phase difference between the reference signal and the controlled signal, and a change in the frequency of the reference signal causes the average duty cycle of the oscillator control signal to change.