Patent ID: 8305155
Filing Date: 2012-11-06
Classification: H03L

Abstract:
1. A phase locked loop circuit which operates with, relative to a reference ground potential, a first supply voltage and a second supply voltage higher than the first supply voltage by a constant voltage, comprising: a first variable voltage source which supplies the first supply voltage; a second variable voltage source which supplies the second supply voltage; a phase detector which operates with a potential difference between the first supply voltage and the second supply voltage, compares a phase of an output signal input to the phase detector with a phase of a reference frequency signal, and outputs a phase difference signal corresponding to a phase difference between the output signal and the reference frequency signal; a charge pump which operates, as a power-supply voltage, with a potential difference between the first supply voltage and the second supply voltage, and outputs a positive or negative constant current signal corresponding to the phase difference signal supplied from the phase detector; a loop filter which integrates the constant current pulse signal output by the charge pump to generate a tuning control signal, and outputs the tuning control signal; and a voltage-controlled oscillator which has an input voltage range of the tuning control signal between the reference ground potential and a third supply voltage, generates the output signal having an oscillation frequency controlled by the tuning control signal, and outputs the generated output signal.