I'm using the ATMEGA328 to make some PWM waveforms, which I'd like to ensure are as low in phase noise as possible. There doesn't seem to be a spec on phase accuracy of PWM outputs, relative to clock.
For example, using a crystal, I'm measuring around 1ns jitter on the clock output, as well as any derived PWM outputs. I assume this is from the crystal circuit.
I'm hoping that if I use a stand-alone oscillator, with specified jitter on the order of 1ps (easily available), the resulting PWM output jitter will be not-too-much higher. Make sense? Obviously I'll try it, but it's tricky to measure, and was hoping there was a spec (or experience) somewhere.