A New Frequency Comparator for Using in Fast Charge Pump PLLs

A bang-bang frequency comparator (BBFC) can be used in the feedthrough path in pump phase locked loops (CPPLL) to increase the locking speed. In this paper, we presenta new structure which can be used as a BBFC and then show how this frequency comparator can decrease the settling time ina charge pump PLL. Simulations in Advanced Design System (ADS2008) using TSMC RF CMOS 0.18um confirm that applying the suggested BBFC can increase the locking speed significantly

Keywords:

Charge pump PLL , BBFC , fast locking