How to isolate substrate noise in mixed signal chip

Jim_Fu

Dear all,

In mixed signal chip, the huge digital block and I/O buffer noise will affect analog circuit performance through substrate,if put the analog block above Deep Nwell will reduce the effect,but some device PNP,Native Transistor are not allowed above Deep Nwell;so I want to put the digital block and I/O circuit above Deep Nwel,but I worry about I/O circuit above Deep Nwell will lead to ESD issue,anyone can give me some suggestion?

Thanks

Jim

cadengineer

Hi,

I am quite intersted in this topic too, as what I know, the deep nwell is a good way to isolate noise from digitial part, usually what peoples concern is that a extra mask needed, and it costs money of course. one alternative is to place a ring around analog region, it helps.

Here I don't understand is, why native device or pnp can't be inside deep nwell? any reason?

sminyi

Now most DNW process is standard. No more money needed.

haibianxia

THANKS

topeeit

native device can, PNP cannot

cywu

tks for your knowledge

lu2zhi4jian1

A new JSSC paper(2012) deals with this problem

totowo

NTN layer,  spacing.....the tradeoff of noise performance is just area

wangandriod

Thx for your knowledge!

alberance

102411