A phase locked loop including switched-capacitor-network operated by the output clock of the voltage controlled oscillator and the method of control the phase locked loop

摘要

A phase locked loop using a switched-capacitor-network operated by an output clock of a voltage controlled oscillator and a control method thereof are provided to decrease a size of the PLL(Phase Locked Loop) by generating a large resistance using a small-sized capacitor. A phase/frequency detector(210) compares phases of a reference signal and a feedback signal with each other and generates an up or down signal according to whether the reference signal leads the feedback signal or not. A first charge pump(220) outputs a first pumping signal according to the up or down signal. A second charge pump(230) outputs a second pumping signal according to the up or down signal. A delay unit(240) delays the second pumping signal according to a divided clock and outputs a delay signal. A loop filter(250) integrates over the first pumping signal and the delay signal and outputs a control voltage. A VCO(Voltage Controlled Oscillator)(260) outputs an output clock according to the control voltage. A first divider circuit(270) divides the output clock and generates a divided clock. A second divider circuit(280) divides the output clock and generates the feedback signal.