[time-nuts] ? phase comparison or other device

[John Miles]

> The output of an opamp is always referenced to its power supply,
> regardless of the configuration.  If the power supply is noisy,
> the output is noisy.

Beyond a few kHz this may be true, but at lower frequencies even a low-grade
opamp has excellent rejection of power supply noise.  A good opamp data
sheet will characterize the PSRR versus frequency.

-- john, KE5FX