Can anybody please tell in detail why we use double and triple guard rings. I know why we use single gurad rings for preventing latch up and noise and how it works.But I am confused about the double guard rings and triple guard rings.
Staggered guard rings serve to better decrease noise impinging into (or escaping from) the surrounded area. It means trading noise immunity against real estate consumption.
A shorted junction (double guard ring) sets up a local depletion
volume which will sweep out minority carriers entering it. A
single guardring only really provides a majority-carrier ohmic
tie and doesn't do much for loose minority carriers. Other
than providing a very small recombination center.
We used to use this scheme for fast recovery diodes and
switching transistor "base plugs", to push down the storage
time.
In simple way, the double guard will increases the protection....If the noise immunity is more then normal level, we will use higher guard ring levels like double guard ring....