Power supplies are a major source of noise in any system. Most of this noise is filtered out by passive filters and decoupling capacitors that are placed on the power supply input of the oscillator. However, some noise remains, which may increase the jitter on the output clock and can negatively impact system timing margins. This noise is amplified when the power supply is switched on, and also when other devices on the board turn on or off during system operation. In a controlled test to evaluate the power supply noise sensitivity performance of various oscillators, a waveform generator was used to add system noise at a specified voltage and frequency to measure the effect of power supply noise on oscillator jitter. As the plot indicates, SiTime's MEMS oscillator jitter is lower across all noise frequencies even when a 50 mV peak-to-peak switching noise is injected into the system.