Ignoring devices during LVS

[d-m-bailey]

@klayoutmatthias Is there a way to ignore devices during LVS?

For example, if the source netlist contains parasitic devices, is there a way to ignore the parasitic capacitors and short the parasitic resistors?

I couldn't find a native klayout lvs command to do this, but is a custom_reader modification possible?

cc: @H-Ojiro

[klayoutmatthias]

Hi @d-m-bailey,

It's possible to ignore irrelevant devices like very large resistors or small capacitors.

But in general reducing a parasitic-annotated netlist to a topological one is a manipulation on a bigger scale, if it is possible at all. You will need to shorten nets when you remove parasitic resistors for example. That is not supported directly. Also, the topology may differ substantially. Hierarchy typically is messed up, as additional pins get generated for the connections of parasitic capacities for example.

Using the netlist API and the script capabilities of LVS, it may be possible to modify the netlist accordingly, but I have not tried that myself. In general it is uncommon to use a parasitic-extracted netlist as reference - at least I have not had this problem myself so far. Specifically as parasitic extraction usually requires a LVS run before the extraction. So in a standard flow, there needs to be that topological netlist somewhere and it is far better suited for input into LVS.

Matthias

[d-m-bailey]

@klayoutmatthias thanks for the response.

I agree with you that using a netlist with parasitics as the source netlist is not a normal use case. I just thought that would be an example of ignoring devices by simple removal or shorting that would be easy to understand.

I practice, I was wondering if it is possible to ignore the ntap1/ptap1 devices in the ihp-sg13g2 pdk by shorting them.