PURPOSE: To eliminate external mounting parts such as IC by measuring a rate with a logical regulation system and a semiconductor variable capacity element.

CONSTITUTION: A semiconductor variable capacity element 22 is stored in the CG side of an oscillation circuit 1 and the oscillation frequency thereof is finely adjusted by applying a voltage to the variable capacitor element. The frequency dividing ratio of a frequency dividing circuit 21 is determined by external switches 10aW10d, and adjusts roughly and stepwise the rate.