PURPOSE: To form a more accurate object frequency by changing the number of programs with a specific count value so as to implement correction when the optional object frequency is generated with a counter comprising a ring counter and a programmable up-counter.

CONSTITUTION: A counter comprising D flip-flops F0-F5 is a 6-bit ring counter and a counter comprising D flip-flops F6-F10 is a programmable 5-bit UP- counter. When a count pulse(CP) frequency is constant and a specific object frequency is generated, a gate G0 to detect a specific count of ring counter is provided and a usual count value and a count value of a ring counter for a specific case are changed by varying the number of programs to make the frequency closer to the object frequency.