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Old 7th May 2009, 10:57 PM   #1
cuibono is offline cuibono  United States
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Default Why does this opamp hiss?

Sorry, noob question:

I'm working up an active filter circuit - in fact I've built it. It works as planned, but it has a noticeable amount of hiss. I'm'sure this is an EE101 question, but for better or worse, I never had EE101. Could someone point out the obvious?

By the way, the opamp are two quad packages, the TI TL054. I was hoping to share what this is for with the board, but it's not ready yet...

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Old 8th May 2009, 01:19 AM   #2
infinia is offline infinia  United States
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Opamp voltage noise... the TL's are intended for instrumentmentation apps with a zener (noise source) trimmed for low offset voltage. The good part is your circuit uses low value resistors and low gains to minimize the current noise (only with low impedance input drive).
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Old 8th May 2009, 11:40 AM   #3
cuibono is offline cuibono  United States
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Thanks! The opamp's voltage noise was at the top of my list of suspects, but I was worried I had done something somewhere else I was unaware of.

But thats good - I only have to switch out the opamps! Much easier than having to redo the whole thing.


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