If I have multiple capacitors from VCC to GND, wou...
# lvsr
Rita
12/30/2022, 7:39 AMIf I have multiple capacitors from VCC to GND, would the LVS software combine them into 1 capacitor?
m
Mitch Bailey
12/30/2022, 8:45 AMIt depends on the setup file, but I think that, yes, the standard mimcap devices have parallel reduction enabled. Also note that mimcap devices are polarized, meaning the terminals are not reversible between the layout and schematic.
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Rita
12/30/2022, 8:46 AMaren't mim capacitors unpolarized in real life
Rita
12/30/2022, 8:46 AM(like ceramic capacitors)
m
Mitch Bailey
12/30/2022, 8:48 AMThe parasitic capacitances extracted are different between the top and bottom metal layers, which may be reflected in the simulation models.
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Rita
12/30/2022, 8:55 AMthanks for your help, I noticed that was why the LVS didn't match
Rita
12/30/2022, 8:56 AMI had capacitors in both orientations
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Rita
12/30/2022, 8:41 PMAre NFETs orientation dependent too
Rita
12/30/2022, 8:41 PMI thought they were symmetrical...
m
Mitch Bailey
12/30/2022, 9:04 PMSOME nfets are asymmetrical.
As far as LVS is concerned, be sure you’re using the correct setup file.
$PDK_ROOT/$PDK/libs.tech/netgen/${PDK}_setup.tcl