Other Parts Discussed in Thread: LMC6482
I have one gate of an LMC6484 acting as a noninverting voltage follower. The input signal to the circuit is at about 1.6V, with 300kohm of equivalent thevenin resistance and attached to the opamp's positive input. The opamp's output is connected directly to the negative input to form a voltage follower circuit. the opamp output sees a load of about 2k. The opamp is connected between 5V and 0V for power. The circuit seems to have an offset error of 50mV, while the datasheet indicates it should be about 0.1mV. As far as I can tell, the circuit is stable with the input at 1.60V and the output at 1.65V - that is, I don't see any oscillation going on, or any indication that the outputs are railing out. Multiple boards wit this circuit on it have the same issue. Other circuits on the same board, that use the other 3 gates of the quad opamp package, do not exhibit this problem. They have lower input resistance so I suspect this may have something to do with that 300k resistance in front of this particular circuit. I have tried tying another 300k resistance between the negative input and ground, to compensate for input bias currents but it has not had any effect. Any idea why this circuit might cause the LMC6484 to have a larger-than-specified voltage offset?