Guard ring questions in 90nm TSMC

[jgk2004]

Hello all,

Question about guard rings in analog blocks. Is it recommended in 90nm cmos to put a guard ring around each device? or just around ALL pmos(Nmoat connected to VDD) then around ALL Nmos(pmoat connected to Vss).

Also what about input pairs? A guard ring around them?

Also what about large output transistors 300uA+ currents? a ring around them?

Also what about around MIMcaps? Nmoat?

Thanks

Jgk

 

[varma_cs012]

First of all, I am not able to understand your question fully!

Are you talking about the G-ring or Substrate contact?

 

[jgk2004]

Guard rings which are a ring of substrate contacts if its an Pmoat ring

 

[deepak242003]

Is it recommended in 90nm cmos to put a guard ring around each device? or just around ALL pmos(Nmoat connected to VDD) then around ALL Nmos(pmoat connected to Vss).

No. You need not put guard ring around every device....however for some critical transisitors it might have to..

Also what about input pairs? A guard ring around them?

Yes. (assuming diffential pairs..)

Also what about large output transistors 300uA+ currents? a ring around them?

I believe guard ring doesnt play much role in current handling..... But it is good to put them around them to suppress noise injusction into substrate.

Also what about around MIMcaps?

I dont think it is required.. because you metal is already well above the substrate...

Let me know if there is any other views.


Thanks