I'm seeing an error while writing GDS: `CIF error in cell twin_tee, layer RPM: parent and child disa...

Matt Venn

05/14/2024, 1:35 PM

I'm seeing an error while writing GDS:

CIF error in cell twin_tee, layer RPM: parent and child disagree on CIF

Matt Venn

05/14/2024, 1:35 PM

image.png

Matt Venn

05/14/2024, 1:36 PM

it seems to be the resistor on the right

Matt Venn

05/14/2024, 1:37 PM

gds is here: <https://github.com/mattvenn/tt07-twin-tee-opamp-osc/blob/main/gds/twin_tee.gds>

Matt Venn

05/14/2024, 1:37 PM

and the mag is here: https://github.com/mattvenn/tt07-twin-tee-opamp-osc/blob/main/mag/twin_tee.mag

Matt Venn

05/14/2024, 1:38 PM

I think this happened because I was cleaning up the directory and accidentally removed a resistor before commiting it

Matt Venn

05/14/2024, 1:38 PM

then I had a hard time re-creating it for some reason, and in the process I also lost the top 2 resistors.

Matt Venn

05/14/2024, 1:38 PM

So I had to make them again with pcell generator

Matt Venn

05/14/2024, 1:40 PM

image.png

Matt Venn

05/14/2024, 1:40 PM

this is what I see after writing the gds

Matt Venn

05/14/2024, 1:40 PM

I don't know why it's just the right hand cell

Mitch Bailey

05/14/2024, 2:40 PM

@Tim Edwards Here’s the resulting gds RPM layer. The synthesis for RPM includes

grow-min

but

grow-min

says that it should only be used on simple shapes.

Copy code

layer RPM
        bloat-all xhrpoly xpc
        grow 200
        grow-min 1270
        grow 420
        shrink 420
        calma 86 20

The problem with grow-min is that it only works well for simple, isolated rectangles.

Maybe the pcell generator shouldn’t make resistors with bends. @Matt Venn you only included the top level mag file. Can’t see what’s in the resistor pcell. You might try

cif see RPM

to see what gds data will be generated in magic.

Tim Edwards

05/14/2024, 2:56 PM

@Matt Venn: "Parent and child disagree on CIF" is not necessarily an error. It means that the GDS writing rules (namely statements like

grow-min

) are inconsistent in how they are applied to a cell when the cell is by itself vs. when the cell is inside a larger cell. The result can be an error but usually isn't. If you run the klayout DRC deck and it doesn't identify a DRC error related to RPM then the layout should be okay.

Matt Venn

05/14/2024, 3:56 PM

ok, I fixed a bunch of other errors that I had, and got rid of the gds error by moving the resistor

Matt Venn

05/14/2024, 3:56 PM

thanks both

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