Hi all,
I'm trying to measure several input impedances of an amplifier in LTSpice, using these two methods:
As far as I knew, the results shoud be the same in either case, but they differ a lot.
The circuit I'm testing has several stages but, for the purpose of the analysis, I've tried with this setup where you can see the results:
Interestingly enoug, If I remove the BJT section, both methods yield the same result:
What I'm I missing? Is there a method I can use that yields consistent results every time?
Thanks!
I'm trying to measure several input impedances of an amplifier in LTSpice, using these two methods:
- AC Voltage source (Vs) at the test point (vin), AC sweep, and a linear plot of V(vin)/I(Vs)
- AC current source (Is) at the test point (vin), AC sweep, and a linear plot of V(vin)/I(Is)
As far as I knew, the results shoud be the same in either case, but they differ a lot.
The circuit I'm testing has several stages but, for the purpose of the analysis, I've tried with this setup where you can see the results:
Interestingly enoug, If I remove the BJT section, both methods yield the same result:
What I'm I missing? Is there a method I can use that yields consistent results every time?
Thanks!
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