The ones we use are from MuRata (NFL18ST).
When you say it's coming "out of" the FPGA... How? Power? Signal pins? Air? In any case it is weird. Did you ask Xilinx about it?
The filters were making my output driver (LM7171 DSL driver used in a Howland current pump) oscillate at 160MHz and suck gobs of power. Bridging them with a zero ohm resistor eliminated the problem, but as I said, it can be tricky with the ground stripe in the middle.