A circuit includes a signal generator to generate an output signal to vary the switching frequency of a switching circuit to mitigate noise in the switching circuit. The signal generator includes a modulation waveform generator (MWG) to generate a ramp signal in response to a numerical input and a switching signal from the switching circuit. The ramp signal is employed to modulate the frequency of the output signal of the signal generator over a range of frequencies from a minimum frequency to a maximum frequency. A frequency adjuster circuit modulates the amplitude of the ramp signal by adjusting at least one of the minimum frequency or the maximum frequency of the range of frequencies.