Hi all,
I have a very peculiar problem with some digitally controlled impedance (DCI) inputs on a Virtex2 device: whenever I enable the DCI on the inputs the signal levels go way down, without DCI I see about 800 mV and with the DCI on about 200 mV. The IO standard is HSTL_I_18, this is a QDR Sram interface design. Another strange thing is that I only see this behavior on the XC2V8000 device, the XC2V4000 and XC2V6000 devices work fine on the same hardware!? Any suggestions? Thanks,