Compensated phase locked loop circuit.

摘要

A Phase Locked Loop (PLL) circuit (100) includes a compensation circuit (120) which corrects for non-linear sensitivity of a varactor of a voltage controlled oscillator (VCO) (104) which is part of the circuit. The varactor is employed as a capacitance tuning element. The compensation circuit controls the sensitivity of a charging/discharging circuit (a charge pump 114) of the PLL circuit with a feedback signal which is derived from an input to the VCO. The sensitivity characteristic of the charge pump is made the complement of the non-linear portion of the VCO sensitivity characteristic.