Op Amp Selection

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Bob Scott
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Joined: Wed Nov 20, 2002 1:01 am
Location: Vancouver, BC

Re: Op Amp Selection

Post by Bob Scott » Thu Jan 21, 2010 8:07 pm

Robert Reed wrote:Bob
I am a little confused by:
"Um, his requirements have an amplitude gain of 60X. That's the amplification factor. Conservative design says that the open loop gain of the op-amp should be 20dB higher for good corrective feedback, or 10X higher. That's 70X total open loop gain. When the loop is closed as normal operation, the circuit gain is 60x."

A voltage gain of 60x is a 37.6 db gain. Open loop feed back safety factor increase of 20 db on top of the required 37.6 db would be 57.6 db. 57.6 db of gain is equal to a gain of 600x. A 60x required and 70x (open loop) would represent a gain increase of approx. 1.3 db.
I just got home from an all day ski trip, so my thinking may be a little groggy.
No. It is my error, my brain fart. I just hope it is not age related and the start of dementia. :shock: I seem to be having trouble keeping all my marbles in the bag. :???:
-=VA7KOR=- My solar system includes Pluto.

Robert Reed
Posts: 2276
Joined: Wed Nov 24, 2004 1:01 am

Re: Op Amp Selection

Post by Robert Reed » Thu Jan 21, 2010 8:24 pm

Don't we all! :grin:

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