Delay locked loop having charge pump gain independent of operating frequency

Abstract

A delay looked loop (DLL) having a charge pump gain independent of the operating frequency of the DLL. A charge pump is disclosed for providing a charge to a capacitive element on a voltage controlled delay line, wherein the charge is independent of a control voltage step cycle time of the DLL, the charge pump includes: a charge/dump signal generation stage that generates a charge signal and a dump signal during each period of a reference clock signal; a first switched capacitor stage that charges a first capacitor in response to the charge signal and dumps a positive charge from the first capacitor in response to the dump signal; a second switched capacitor stage that charges a second capacitor in response to the charge signal and dumps a negative charge from the second capacitor in response to the dump signal; and an output stage that selectively loads either the positive charge or the negative charge to the capacitive element on the voltage controlled delay line in response to an input signal from a phase detector.