Which is inside, PTAP or NTAP guarding?

[mssong]

I am doing a mixed signal layout.

I have some confusion about double guarding.

I know I have to hit the NTAP guarding for PMOS and the PTAP guarding for NMOS, but if I have both PMOS and NMOS (ex: AMP), which one of the NTAP and PTAP should be on the inside to guard that block at once?

My thought is that the ntap guarding (VDD connection) should be on the inside and the psub guarding (VSS connection) should be on the outside, which would be the most resistant to board noise.

 

[dick_freebird]

Your tap is same species as the well, opposite the S/D species. Any fancier ring(s) go outboard.

 

[HoseinAli]

I think GND/VSS should be the outer ring since the top metal layer is filled with GND for noise prevention, so this rule may apply to other sides

 

[sidun.av]

I am doing a mixed signal layout.

I have some confusion about double guarding.

I know I have to hit the NTAP guarding for PMOS and the PTAP guarding for NMOS, but if I have both PMOS and NMOS (ex: AMP), which one of the NTAP and PTAP should be on the inside to guard that block at once?

My thought is that the ntap guarding (VDD connection) should be on the inside and the psub guarding (VSS connection) should be on the outside, which would be the most resistant to board noise.

You should probably get yourself more familiar with a cross-section (and physics) of the CMOS process. You cannot guard both PMOS and NMOS with common NTAP and PTAP rings - each device type has to be protected separately.