Hi guys, does anyone have a rational reason as to ...
# sky130t
Thomas Pluck
03/23/2023, 4:02 PMHi guys, does anyone have a rational reason as to why the default area parameter of diode models in ngspice are set to 1e12 to represent a 1 micron^2 diode? It seems a bit odd to measure diode area in picometers squared.
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Boris Murmann
03/23/2023, 4:48 PM1e-6*1e-6 = 1e-12. Diode area has been specified like this in Spice since its inception.
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Thomas Pluck
03/23/2023, 5:26 PMThanks for the reply! So, a 100 micron^2 device would be represented by 1e14 like in this message?
https://open-source-silicon.slack.com/archives/C016UL7AQ73/p1658700853488009
Shouldn't it be 1e-10 - to stay in SI units?
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Boris Murmann
03/23/2023, 5:34 PMOk, I now understand what you mean. It's important to distinguish simulator and pdk. Based on what @Stefan Schippers wrote, there is an odd scale factor baked into the Is of the diode model in the SkyWater pdk.
Boris Murmann
03/23/2023, 5:37 PMSo yes, it seems that a 100um^2 device in the SkyWater pdk needs an area parameter of 1e14. This doesn't have much to do with ngspice.
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Thomas Pluck
03/23/2023, 5:39 PMAh, sorry, I should've been clearer. So, its just a quirk of the PDK.
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