This paper presents an extensive look at dithering, a form of frequency modulation, commonly used for integrated relaxation oscillators in order to achieve a wideband spread of output noise. A particular relaxation oscillator topology is chosen as a reference. Linear dithering, step dithering and sinusoidal dithering are analyzed in terms of the dithering frequency and dithering percentage. A discussion on the implementation of these techniques is made. Simulation results for applying these techniques to the proposed oscillator show roughly the same baseband amplitude reduction, but a lower total spectral power for sinusoidal dithering. An experimental version using discrete devices is implemented and tested, confirming the simulated results.

Keywords: Dithering, Frequency modulation, Noise spread, Relaxation oscillator, Spread-spectrum