I have been trying an OP211 as an input buffer and find it to be far noisier than advertised. I have tried 4 or 5 and I get a voltage noise of about 2.3nv/roothz instead of the 1.1nv claimed. I do not think it is my setup as using other low noise op amps gives their advertised values. I am running broadband so the1/f noise is irrelevant. Has anyone else experienced similar problems with the 211? It is not an oscillation as it goes down as the inverse of the square root of the number of traces I average, just the way noise should.
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