I'm having trouble with simulating a Sallen-Key single-supply low pass filter using LTSpice. After fiddling around with the circuit for an hour I'm hoping for some assistance in troubleshooting.
For a transient analysis I'm inputting a 1 Khz 1 V signal and apply a DC offset. The gain should be 1 at this frequency. But at the output of my filter I'm getting a very very small amplitude centered at the DC offset.
For an AC simulation I'm inputting a small-signal AC amplitude of 1V. Again, I see a very small gain, and this time it's shown to be across all frequencies.
Based on the circuit design, these results are not what I would expect. I think my error must be in how I am implementing it using LTSpice, which I'm not an expert in using. I'd appreciate any input on what I might be doing wrong.