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