PURPOSE: To obtain a filter with broad band characteristic by providing a means to allow a PLL circuit to control a steep change in a control signal, and driving the PLL circuit with a reference signal having a frequency fref in a frequency band fw.

CONSTITUTION: A phase comparator (PFC) 51 detects a difference of rise times of input signals 511, 531, and outputs a signal 513 (UP signal) having a pulse width corresponding to its time difference when the signal 511 rises early and outputs a signal 514 (DOWN signal) when the signal 531 rises early. Moreover, a loop filter (LPF) 52 consists of a current source (current: Ip) turned on/off by UP, DOWN signals and a capacitor (capacitance: C). The oscillating frequency fvco of a voltage controlled oscillator(VCO) is controlled by an LPF output voltage Vg and an output signal 541 of a control circuit 541. Thus, the filter for broad band or high frequency is easily realized.