Simple inductor PCell

[adrienluitot]

This PR add a new kind of inductor PCell layout. It's not a differential one like the inductor2/3 currently proposed by the PDK. It allows a lower serial resistance and thus a higher Q (at least around few GHz), measured with OpenEMS.

I haven't tried to LVS, I don't know how it will react.
The code is highly based on the inductor type 2 code.

I would like to add callbacks on the parameters, I could add them before the PR is merged. But I don't know how to implement them, I haven't found an example in current PCells. I could also add them in an future PR, when I know how it works.

The inductor looks like that in KLayout:

[VolkerMuehlhaus]

Removing the crossovers results in higher Q indeed, if you don't need symmetric layout.

Another possible layout modification to increase Q, which also work for symmetric layouts: You can stack TopMetal1 and TopMetal2 for the coil turns whereever possible. Place a few vias every 90° to connect the metals.

[adrienluitot]

Thank you for your feedback, it's indeed for non symmetrical layouts.

Stacking is a good idea too, why not exploring it some day.

[sergeiandreyev]

Hi @atorkmabrains, @FaragElsayed2, could you please take a look if the LVS will work with this new inductor device or there will be some change needed to be compatible with OpenPDK?