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#analog-design
Title
# analog-design
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Stefan Schippers

01/18/2022, 2:19 AM
Another interesting variation is to use the ngspice AC/DC resistor: a resistor can have an "AC=val" that overrides normal resistor value for AC analysis. This can be used to open the loop and connect the AC signal source:
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Tom

01/20/2022, 3:09 AM
Oh the ac resistor sounds great 👍🏻, I'm going to give that a try! Thank you both for these suggestions @User @User. I've tried the filter technique before actually but I don't like the fact that it's frequency dependant, albeit very large. The ac resistor sounds great. I didn't realize that was an option
@User what does the netlist entry look like for those resistors? I can't get it to work...
Copy code
r2 vo net7 dc=0.1 ac=1g
  unknown parameter (dc) 
    Simulation interrupted due to error!
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Stefan Schippers

01/20/2022, 9:33 AM
@User are you using Xfce or ngspice? for ngspice the syntax i this
R2 net1 net2 10G ac=0.1 m=1
the dc value does not need "DC="
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Tom

01/21/2022, 3:35 AM
I'm using ngspice. That syntax is working for me now, thanks, @User