This is useful if you have a complex circuit and are only trying to test one portion and want to ignore another that would otherwise slow things down.

If you’re doing a quick sim, you can simply “Do Not Populate” the instance with Shift+D. The downside to this is that it hides it in the cell itself, meaning that if someone else is also testing or working with that cell in a testbench it’ll hide it for them too.

A safer way to do it is with a config view. Go to your top level testbench and create a new cell, and select config. Select the necessary libraries, and then the expected views, and then what’s considered the “leaf” view. These settings tell the simulator in what order to look for a particular cell, so the order is very important. A simple example would be if you had a regular schematic or an post-layout extracted (av_extracted) view. If you put av_extracted view higher up on the list, then that’s the version it’ll default to for any cell that has it. The “leaf” view is the lowest priority and tells it “If you find this view for this cell, stop looking”.

What we then want to do is go to the hierarchy tree list, right click on the instance you want to hide, and click “Bind instance to open”. What this does is it tells Cadence to skip this instance in the netlisting process. It however does not pass this info on to spectre, so spectre will suddenly see a bunch of open circuits and throw warnings, so it’s a bit “dumb” in that way, but you can safely ignore those warnings so long as hiding that instance doesn’t affect the parts of your circuit you do want to simulate.