I'm having a difficult time figuring out how the attached bandpass filter works - what sets F0, Q and Gain. I think the two lower opamps centered at Vcc/2 are acting as integrators but I'm baffled by how the feedback is applied to set the filter's parameters. Thanks!
It is the popular KHN-topology with two inverting MILLER integrators. The output of one integrator is fed back to the pos. input of the gain stage, and the other outputis connected to the inverting opamp input. Recommendation: Google for KHN filter (Kerwin-Huelsman-Newcomb).