Hi, this is a basic question. I have an inverter model from a extracted layout in magic (Fig 1) and ...

Nelson Rodriguez

04/22/2023, 12:24 PM

Hi, this is a basic question. I have an inverter model from a extracted layout in magic (Fig 1) and I want to add that model in a testbench in xschem (Fig 2) could anyone indicate me, how can I add the spice description to a symbol, because I only know how to create symbols from schematics, but never from a spice file like this. Thanks in advance

Stefan Schippers

04/23/2023, 7:10 AM

Go through this manual page.

Stefan Schippers

04/23/2023, 7:18 AM

You can descend into the symbol and edit its global attributes (press 'q' in the symbol without anything selected), set

type=subcircuit

and add the following attribute at the end:

spice_sym_def="

.subckt inverter A Y VPWR VGND

...

...

...

.ends

that is copy the thesis_inv text into it. Alternatively you can do:

spice_sym_def=".include /path/to/thesis_inv.ext'

when generating the netlist ensure the pin order of the

inverter

symbol matches your extracted netlist. If the pin order does not match change the order in the text file above. You see above i have renamed

thesis_inv

inverter

since this is the name of the xschem symbol.

🌍 1

z-a-p-k-i-n-g

04/25/2023, 2:15 AM

@Nelson Rodriguez Does this method of using (type=subcircuit) work for you?? Somehow this doesn't seem to work for me

z-a-p-k-i-n-g

04/25/2023, 2:53 AM

However using type=primitive and setting device_model=".include path/to/file" works... But I am curious to get the other method working

Stefan Schippers

04/25/2023, 7:21 AM

@z-a-p-k-i-n-g ensure the text for

spice_sym_def

is properly quoted. If there are double quotes inside the (quoted) text these must be escaped (

\"

)

Copy code

spice_sym_def="...
...
...
..."

z-a-p-k-i-n-g

04/25/2023, 7:27 AM

@Stefan Schippers Ig it's all good...but still it continues to expand .sch file instead of using the value of spice_sym_def attribute

Stefan Schippers

04/25/2023, 7:30 AM

@z-a-p-k-i-n-g do you have a recent

xschem

? this feature was added end of september 2022. if not try to update and rebuild. the spice_sym_def attribute must be placed in the symbol. Descend into the symbol, press 'q' and add the spice_sym_def attribute.

z-a-p-k-i-n-g

04/25/2023, 7:33 AM

I am using ngspice-40...let me try rebuilding xschem🤞

z-a-p-k-i-n-g

04/25/2023, 8:24 AM

@Stefan Schippers Thank you... rebuilding it solved the issue

🌍 1

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