PURPOSE: To convert a frequency of an input signal CK into a frequency of a special multiple with equal duty ratio by using variable delay circuits whose delay is equal to each other to eliminate a tracking error between the variable delay circuits.
CONSTITUTION: In the frequency conversion circuit converting a frequency of an input signal CK, a circuit 1 applying 1/2 frequency division to the input signal CK, three delay circuits 3a-3c having a delay of T0/4 with respect to a period T0 of the input signal CK, two multipliers 4a, 5 multiplying outputs of the delay circuits and a multiplier 4b multiplying outputs of two preceding multipliers are used to convert the input signal CK into signals with equal duty for two multiple, multiple and 1/2 frequency division. As required, the signals are given to a 1/3 frequency divider circuit to provide an output of 1/1.5 and 1/3 frequency division signals with equal duty.
KAWASAKI MOTOAKI
IZEKI MASAMI
