As systems adopt smaller form factors and increased integration, the significance of power supply noise immunity becomes increasingly important. This is especially true for applications that use differential reference clocks because of the need for low jitter. Most oscillator specifications are based on lab tests that use a clean power supply. However, this performance is not always maintained in actual systems because of noisy power supplies in the field. Noise on the power supply is often coupled to the output, degrading performance significantly. This plot shows power supply noise sensitivity in units of ps/mV, and lower numbers therefore mean better performance. In this test, a 50-mV sine wave is AC-coupled onto the voltage supply pin, and the jitter resulting from this 50-mV sine wave is measured at the clock output. As shown, the performance of the SiT9365 oscillator is up to two to three times better than the other quartz devices. To filter power supply noise, SiTime oscillators have integrated multiple power supply regulators on chip and up to two stages of voltage regulation.