Patent ID: 8400198
Filing Date: 2013-03-19
Classification: H03L

Abstract:
1. A semiconductor integrated circuit having a phase locked loop circuit built therein, the phase locked loop circuit including: a phase frequency comparator; a loop attenuator; a charge pump; a loop filter; a voltage controlled oscillator; and a divider, wherein the phase frequency comparator compares a difference in phase between a reference signal and a feedback signal that is an output signal of the divider and outputs a first output signal and a second output signal each used as a phase-compared output signal, wherein the loop attenuator outputs a charge pump drive output signal supplied to the charge pump in response to the first output signal and the second output signal, wherein the charge pump outputs a charging current or a discharging current to the loop filter in response to the charge pump drive output signal outputted from the loop attenuator, wherein the loop filter outputs a control voltage supplied to the voltage controlled oscillator in response to the charging current or the discharging current outputted from the charge pump, wherein the voltage controlled oscillator outputs an oscillation output signal supplied to the divider in response to the control voltage outputted from the loop filter, wherein the divider divides the oscillation output signal outputted from the voltage controlled oscillator to thereby output the feedback signal supplied to the phase frequency comparator, and wherein, when the phase of the feedback signal lags the phase of the reference signal: