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Question on biasing circuitry - RF Cafe Forums

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Below are all of the forum threads, including all the responses to the original posts.


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?


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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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