We need to check the layout for BCI test. I have a board that can't pass this test all the time, I've tried many ways to pass it using CMC, LC, FB filters. Finally, the other day, I measured between the filtered GND and the unfiltered GND with the LCRmeter, and I saw 500ohm impedance at 1MHz. My test is between 1-400MHz. My guess is that, because of the layout, the signal is returned directly from GND, not via CMC. My question is, how can I detect such problems with Hyperlynx during PCB design? If I give noisy signals to VCC and GND, can I get the signal waveform at the filter input? Then I can design the filter with spice according to this form.