Patent ID: 6278304
Filing Date: 2001-08-21
Classification: H03L,Y10S

Abstract:
An apparatus comprising:a digital phase detector to generate direction control signals based on a reference count signal and a pre-scale count signal from reference and pre-scale counting circuits, respectively, the direction control signals including an up direction signal and a down direction signal and controlling direction of current pumped by a charge pump circuit biased by a charge pump bias circuit, the digital phase detector comprising:a first synchronizer to generate the up direction signal based on the reference count signal from the reference counting circuit, a second synchronizer to generate the down direction signal based on the pre-scale count signal from the pre-scale counting circuit, and a reset generator coupled to the first and second synchronizers to generate a reset signal, the reset signal resetting the first and second synchronizers; anda charge pump enable generator coupled to the reference and pre-scale counting circuits to generate an enable signal based on a look-ahead reference count signal and a look-ahead pre-scale count signal from the reference and pre-scale counting circuits, respectively, the look-ahead reference and pre-scale count signals being generated before the corresponding reference and pre-scale count signals by a predetermined time interval, the enable signal powering down the charge pump bias circuit after the charge pump circuit pumps the current.