PURPOSE: To stop an oscillation even after applying supply voltage, and to control the period of the oscillation by fitting an external signal input terminal between an output terminal for a buffer circuit and an input terminal for a voltage doubler rectifier circuit.

CONSTITUTION: An external signal input terminal EXT is fitted at a node between an output terminal for a buffer circuit 2 and an input terminal for a voltage doubler rectifier circuit 3. When signals having waveforms as shown in the figure are transmitted over terminals such as gate terminals A, B, D, a signal having a waveform as shown in the figure appears in a node N2. When a signal as shown in the figure is inputted from the external signal input terminal EXT, the waveform of a signal appearing at a node N3 also changes according to the waveform. When oscillating frequency is intended to be controlled, a signal oscillating for some period by potential between supply potential and gounding potential is inputted from the terminal EXT. An oscillation can be stopped by inputting supply potential of fixed voltage to the terminal EXT.