Electronics > Beginners
Measuring transconductance of any circuit
Wimberleytech:
Here is another way.
Build the test setup using current source and controlled source as shown.
Run transient analysis.
Measure the voltage at the input of the DUT.
Since I and V are known, calculate GM.
promach:
--- Quote ---Build the test setup using current source and controlled source as shown
--- End quote ---
1) Is E1 a transconductance simulation element ? If yes, it seems not really practical to assign value of 100 to E1 ?
2) Any reason for using "sine" current source ?
3) Why transient analysis ? I suppose doing a DC sweep across Vin and doing derivative on Iout and Vin is the definition of Gm ?
Wimberleytech:
--- Quote from: promach on December 16, 2018, 01:16:32 am ---
--- Quote ---Build the test setup using current source and controlled source as shown
--- End quote ---
1) Is E1 a transconductance simulation element ? If yes, it seems not really practical to assign value of 100 to E1 ?
--- End quote ---
Why (Why not)?
E1 is functioning like an opamp. Something higher than 100 would be better, but I was concerned about convergence.
--- Quote ---2) Any reason for using "sine" current source ?
--- End quote ---
It is easy...it works
--- Quote ---3) Why transient analysis ? I suppose doing a DC sweep across Vin and doing derivative on Iout and Vin is the definition of Gm ?
--- End quote ---
You do not need to do a derivative. Measure delta voltage...you know the delta current. Algebra.
promach:
Did you forget the capacitor which is the important component in a gyrator implementation of inductor ?
Wimberleytech:
--- Quote from: promach on December 16, 2018, 01:30:14 am ---Did you forget the capacitor which is the important component in a gyrator implementation of inductor ?
--- End quote ---
No. I am calculating Gm. Certainly Gm has some frequency dependence...you can factor that in when you pick the sine frequency.
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