Well I'm struggling today, maybe I'm putting too much thought into this. I'm trying to design the proper virtual gnd circuit for my opamp filter. In real life my output will be a DAC with a current source into a 75 Ohm resistor. The resulting voltage will always be positive since the current source is always positive.
So anyway I wanted to do an AC simulation in spice to make sure my changes to make this filter a single supply would work. I don't quite understand why the simulation only matches the dual supply one if I put a 2Vdc offset on the AC source, 1Vdc offset results in much more attenuation at high frequencies.
The other thing I struggle with is I don't even know if this is the right way to model my source. I feel like putting this strong DC offset in the AC source is throwing off my understanding of the virtual gnd circuit.
I've been trying different things and went back read about how AC simulations work, but still feeling frustrated by not understanding everything here.
Does anyone have any insight on why it only works at 2V offest, and if there is a better way to model my input?
The opamp I'm using is the Analog devices AD8051