Method and apparatus for effecting analog phase-locked loop control of a

Abstract

An integrated circuit (100) contains an analog phase-locked loop circuit having a phase detector circuit (16) which compares the phase of a reference signal (28) to the output (12) of the phase-locked loop circuit, a charge pump circuit (18) responsive to the phase detector circuit for varying the charge on a capacitor (36) of a loop filter circuit (20), a regulator circuit (22) which receives two separate control voltages (38, 44) from the loop filter circuit, and a voltage controlled oscillator circuit (24) which receives from the regulator circuit two separate control voltages (VIN, VREG). The voltage controlled oscillator circuit is designed to work with a relatively low regulated voltage, and the regulator circuit is implemented with n-channel devices. The two control voltages respectively effect coarse and fine adjustment of the frequency of the output signal from the phase-locked loop circuit.