I am working on a circuit that is supposed to be a multiple feedback band pass filter at 16900Hz. On my breadboard I get a reasonable approximation to what the math/theory expects, but when I moved my circuit to 0603 parts on a two layer board it gets much worse - especially at the low end. I would expect it to get better on a PCB, not worse! (Tighter loops etc).
Attached is an image with the expected response (blue), PCB response (green) and breadboard response (orange). Also attached is a of the layout, the real life pcb and the breadboard and schematic. (Ignore extra components on the breadboard, they're not connected).
Is there coupling going on in the board? I can't think of anything that would cause such a worsening in frequency response, especially at the low end.
How can I modify my design to get closer to the ideal frequency response?
All resistors are 1%, caps are 10% or 20% X7R.
Thank you.