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AD8221 spurious DC offset

Question asked by JoeK on Feb 16, 2017
Latest reply on Jul 21, 2017 by ARoxas

I am using the AD8221 with +/- 15V supply. I recently put new amplifiers on my board and on power up with no applied input signal the output of one of the amplifiers is ~2.5VDC. Another amplifier has a similar problem with a different output voltage, and two more of them appear fine. The two with problems also seem to be outputting a voltage onto one of the inputs - they each have an input terminal with non-zero voltage even though the other nodes in the circuit are grounded. 

I had previously seen other AD8221 chips with that problem and assumed they were broken from having applied an input signal without a power supply. These chips are brand new on a custom PCB, not an eval board. 

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