A question on mixed signal design

[santhosh.mandugula]

hi all, i want to know how to isolate analog and digtal layout blocks in mixed signal IC design. Any double guard ring arrangement id used for that???
After seperaration, if there are any connection between them, how to connect them???
Thanking u in advance...

 

[A.Anand Srinivasan]

as far as i know guard ring serves the purpose.... the connections are through the wire( metal layer) so i dont think that would be a real problem....

 

[caosl]

how about deep nwell isolation?

 

[raduga_in]

Guardring is solution to the problem of latup .. not
for reducing the substrate coupling .. the only
possible way is Deep Nwell Isolation.

 

[milkdragon]

Dnwell isolation is useful for low frequency isolation, but not effective for high frequency. For SOC, ppl use a wide substrate contact for isolation (with isolated bond pad and bondwire. Some ppl also use a combination of nwell and substrate for further improvement

 

[santhosh.mandugula]

hi... thanx 4 all. The below link gives some idea about deep n-well process and by seeing the diagram provided u can come to know how to separate analog and digital blocks in mixed signal ic design using deep N-well process

 

[leo_o2]

If there is no deep nwell, what kind of guard ring is the best for isolation?

 

[engrak]

i think doble gaurd ring will do better.

 

[deepak242003]

I suggest use of both of psub and nwell guard ring..especially on analog circuit. It will prevent both substrate noise and minority carrier injection. If space permits, use around digital block also.