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AD8041/AD8041S Input Impedance/Bias/Resistance

Question asked by mcaputo on Apr 24, 2017
Latest reply on Apr 24, 2017 by harryh

I have an application for a rad-hard op-amp that is very sensitive to input impedance / input bias / loading, so I have a few questions about the AD8041 and AD8041S.


1. In the AD8041 datasheet, it states that the input resistance is 160 kohm (with a 5 V supply). Is this resistance measured common-mode or differential, or a combination of the two? (I am basing my terminology off of MT-040).


2. The AD8041S datasheet does not specify an input resistance, but I am assuming it is similar to the AD8041. Is this reasonable?


3. Is the 3.5 uA bias current specified in the AD8041 datasheet into the port, out of the port, or both? It doesn't specify which direction it is.