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[Help-gnucap] Determining impedance between two nodes...
From: |
Hugo van der Merwe |
Subject: |
[Help-gnucap] Determining impedance between two nodes... |
Date: |
Mon, 7 Oct 2002 15:10:37 +0200 |
User-agent: |
Mutt/1.4i |
Are "newbie" questions such as these welcome on this list? :
How can I determine the impedance seen at the input and output nodes of
an amplifier circuit? I've tried adding e.g. Z(23) to find the impedance
at node 23 (my output node). I added it to my ".print ac" line, as I am
interested in AC small signal impedance.
This gave values at the output which looked reasonable, though I haven't
verified them. I want to do the same for the input, but since I had this
as my input:
Vin 3 0 DC 0 AC 10m
the result is of course practically 0. I tried disconnecting Vin to see
what it returns then, but that doesn't work, since that changes the DC
operating point as well.
So how can I get the small signal resistance of the circuit as seen by
the source? Is it also easy to see the small signal resistance seen by
e.g. the internal capacitances of a transistor? (E.g. the small signal
resistance seen between the base/emitter nodes, and the
collector/emitter nodes..)
Thanks,
Hugo van der Merwe
- [Help-gnucap] Determining impedance between two nodes...,
Hugo van der Merwe <=