PURPOSE: To extend the waiting time of the mobile communication terminal equipment by reducing current consumption of a PLL circuit by intermittent drive.

CONSTITUTION: When a PLL circuit is locked while a call is awaited, a CPU 5 latches a DC voltage output of an LPF 3 and it is given to a VCO 1, which is oscillated. On the other hand, application of a power supply voltage VPLL to a PLL-IC 2 outputting a phase difference between an output of the VCO 1 and a reference signal is stopped to reduce current consumption. The power supply voltage VPLL is applied again to the PLL-IC 2 after the lapse of a prescribed time and a loop of the PLL circuit is formed to try locking again.