To double the resolution without raising the frequency of an original oscillation signal by providing an inversion/noninversion control circuit inverting/ noninverting the original oscillation signal and a selection means validating/ invalidating the signal for a programmable frequency divider.

The inversion/noninversion control circuit 1 is arranged in the middle of the original oscillation signal line inputting to a programmable counter 10 to connect an inversion/noninversion selective signal P0 and the counter signal of the inversion/noninversion control circuit. This circuit 1 consists of an OR circuit and an exclusive OR circuit and inputs the output of a frequency halving divider 11 through a delay circuit 30 in order to stabilize the counter signal I of the inversion/noninversion control circuit. In addition the signal P0 indicates the changing timing of the programmable frequency divider 11 to the original oscillation signal and outputs a signal validating/ invalidating the circuit 1. Thereby resolution is doubled without raising the frequency of the original oscillation signal.