a triangular wave generation circuit configured to generate a triangular wave signal:

a pseudo-random number generation circuit configured to generate a pseudo-random number signal;

a limiter circuit configured to perform a limitation process of limiting an amount of change per unit time in the pseudo-random number signal and generate the pseudo-random number signal subjected to the limitation process as a limiter signal;

a linear arithmetic circuit configured to generate a frequency control signal by performing a linear arithmetic operation on the triangular wave signal and the limiter signal; and

an oscillator configured to generate a clock signal having a frequency corresponding to the frequency control signal.