Nwell guard ring connect to local VDD which i see quite noisy because of the swicthing.
The question is when i put Nwell guard ring which connect to local VDD will make my analog block even noisier? or it will not bring side effect and just not function as guard ring?
Noisy VDD can also be a guardring and make analog environment clean. Their function is the reverse biased junction around the analog module to block the noise, however reverse biased junction do also have the parasitic capactior, which may form a path between other blocks and you analog circuits for high frequency noise.