guard ring around a bandgap reference BJT

[vani_s]

Hi,
Is it necessary to put a guard ring around Band Gap Reference BJT's ??
If so, what type of Guard ring (nwell/psub) is preferable ??

 

[erikl]

Yes, it's preferable to use a guard ring against straying charge carriers from the outside BJTs. Its real estate consumption is low anyway compared to that of the BJTs.

psub-to-GND guard ring for pnp's, nwell-to-VDD ring for npn's.

 

[vani_s]

Thank you