PURPOSE: To obtain a log sweep generator having high precision, by applying a certain frequency to the 1st and 2nd counters bia a rate multiplier and at the same time setting the counting value of the 2nd counter at the set value of the rate multiplier.

CONSTITUTION: The output f1 of a rate multiplier RM to which a certain frequency f0 is applied from an oscillator GE is supplied to the counters C1 and C2. At the same time, the counting value (m) of counter C2 is set at the set value of multiplier RM. Thus the output frequency of multiplier RM increases in a way of exponent and function. The output f1 is counted by the counter C1, and a triangular wave is obtained by giving a D/A conversion to the counting value of counter C1. This triangular wave is shaped by a nonlinear circuit NL to be delivered in the form of a sine wave signal.