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Question on biasing circuitry - RF Cafe Forums
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smanoha
Post subject: Question on biasing circuitry Posted: Tue
Apr 25, 2006 2:14 am
Captain
Joined: Tue Apr 25, 2006
2:01 am
Posts: 7
I am noticing a difference in the overall gain
(of an LNA) depending on where the off-chip decoupling capacitors are
placed (close to or away from the chip). Any ideas on why this might
be happening?
Top
fred47
Post subject: LNA bypassingPosted:
Tue Apr 25, 2006 5:36 pm
General
Joined: Wed Feb
22, 2006 3:51 pm
Posts: 104
Even a short trace on a PCB looks
like a non-negligible inductor at a high-enough frequency. So a bypass
capacitor away from the chip might even look inductive, depending on
the length of pcb trace and the operating frequency. That would give
unintended feedback via the power supply pin of the IC, which would
affect the gain.
Good Luck!
Fred
Posted 11/12/2012
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