Patent ID: 7605621

Claim:
An oscillating apparatus comprising: a filter circuit that includes a capacitor and outputs a control signal based on an amount of charge accumulated in the capacitor; an oscillator that outputs an oscillation signal of a frequency that is based on the control signal; a phase comparator that compares the oscillation signal with a reference signal of a predetermined frequency, to detect a phase difference between the oscillation signal and the reference signal; a switch circuit that controls whether to charge the capacitor according to a predetermined charge current or to discharge the capacitor according to a predetermined discharge current, based on the phase difference; and a current stabilizing circuit that defines each of the charge current and the discharge current based on a predetermined reference current or a reference voltage, the current stabilizing circuit including: a phase controlling current supply that is connected to the capacitor, and supplies a predetermined phase controlling current to the capacitor as the charge current; and a charge pump current supply that runs a predetermined charge pump current, and when being connected to the capacitor via the switch circuit, discharges the capacitor, wherein current values respectively of the phase controlling current and of the charge pump current are set to be substantially proportional to the reference current or the reference voltage.