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DC bias point shift - RF Cafe Forums
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kris
Post subject: DC bias point shift Posted: Fri Jan 06, 2006
2:41 am
When I run DC simulations I see that my DC bias point is
correct for my PA but when I run Harmonic Balance simulations my output
waveforms are centered around at completely different point (basically
at VCE=0)...how is this possible?? what could be the problem and how
should I go about correcting it. I've read some things about bias point
shifts but this seems completely odd. As far as I can see my DC/AC blocks
are in the right places so I just don't understand what's going on???
actually, after running HB simulation i plotted the current going through
the collector and it showed a significant value instead of showing 0
because of RFC at the collector. i increased the value of the RFC inductor
but still same problem exist....any suggestions
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IR
Post subject: Posted: Wed Jan 11, 2006 5:15 pm
Site
Admin
Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location:
Germany
Hello kris,
My guess is that your PA is working in
a class which is not class A. So when you run HB simulations and sweep
the input power you see that your current and voltage are swept to extreme
points. To which extent it happens, I can´t tell without knowing how
your PA works, i.e. exactly which class and actual quiescent operating
point?
Could you share some details about these issues of your
design?
_________________
Best regards,
- IR
Posted 11/12/2012
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