US Patent 7443206 High-frequency linear phase-frequency detector with wide-pulse outputs

A circuit and method are provided for detecting a phase difference between at least two periodic signals. The circuit and method disclosed herein provide pulsed output signals with wide output pulse widths well suited for use to drive a charge-pump in a phase-locked loop. The wide pulse widths of the output signals generated by the circuit and method allow the charge-pump to sink or source current with higher accuracy and therefore improve the operational characteristics of the phase-locked loop. Further, the circuit and method disclosed herein allow a phase-frequency detector and an associated charge-pump to operate at a higher operational frequency due to the wide pulse widths.