isolate 2 different sub contacts such as: AVSS, AVSS_SUB

isolate 2 different sub contact such as :AVSS , AVSS_SUB

Hi everyone

IS there any body know, that how to isolate 2 different body
(sub-straight) contacts of 2 different transistor on AMS350 pdk?
for example @ tsmc40 we should drown the "psub2" layer on one of transistors to virtually disconnect from sub-straight...
but at that pdk(ams350) I tried to use any layer like that but it was not solved the LVS issue related to bodies...
TNX
hesam2sh

Re: isolate 2 different sub contact such as :AVSS , AVSS_SUB

As you're talking of a "psub2" layer, I presume you're thinking of NMOSFETs. In such case you'd have to use at least one of them residing in an isolated double or triple well (p-well in an n-well) bulk (body), where you can connect its body to a different potential.

I don't know if your AMS350 PDK provides this option.

Re: isolate 2 different sub contact such as :AVSS , AVSS_SUB

In the end there can be only one substrate unless you are
in a SOI technology.

You may want, and be able to represent different connectivity
in schematics and simulations. But at layout verification the
reality will win out.

Perhaps there is a substrate / bulk "cutter" layer for this
but I believe the proper approach is to make the substrate
a schematic net (not global, there ought to be a sub node
property that can override psub! default connectivity)
and thread this all the way through schematic hierarchy
(so you may impose presistor resistors, which netlist to shorts
in LVS but to values in Spectre) and connect all the sub
nodes at the top level (again, perhaps by presistors).

If you didn't start this way, it will be a whole lot of rip-up
in the schematics, manual property editing and so on.