I've got an AD8001 in a +/-15V circuit. I stuck in some three terminal voltage regulators. (L79L05 and 78L05) The offset voltage from the AD8001, was ~40-50 mV (negative) I've got 1 k resistors everywhere, (input, FB, inv to ground) and 100 ohms on the output. I sorta take worst case numbers from the spec sheet and wave my hands.
But I went looking at the power supplies to it, and when I stuck my 'scope probe on the -5 V, the offset changed (to -30 mV)* I've got 0.1uF on the regulator output.. but nothing on the input... well it's daisy chained from other opamp supplies and those are bypassed too.
I wired up the same circuit on some white proto and stuck in three other AD8001's. Vos was 2mV to 4 mV.
Negative voltage regulators seem to often cause issues.... Anyway I fried it (AD8001) when trying to add some more C, so I'll start again tomorrow.
George H.
*the voltage looked fine on the 'scope, AC and DC.