I am attempting to create a bandpass filter in LTSpice. I am fairly new to the program, which is probably contributing to my difficulties. The filter I am creating needs to have a center frequency of 1200 Hz, with the cutoff frequencies at 1080 Hz and 1320 Hz. While the initial circuit design didn't seem so difficult, I cannot seem to get any working simulations. Here is my current schematic:
Note I initially started with a single stage that also produced similar results to this one. The second stage was added to narrow the bandwidth.
I honestly don't know what to make of this curve... It sure doesn't look like what a bandpass filter is supposed to be. I have triple checked all of my values and the general layout for the circuit, and I am at a loss for what is wrong. I have also a wide variety of other RC values and different OP amps with no success.
Just for testing, I also went ahead and built an active low pass filter. This one is also giving me a very strange frequency curve. Here is the schematic:
and here is the frequency curve:
Any help with this would be greatly appreciated. I am currently at a loss for other things to try. Thanks!