Why does my single rate or interpolating half-band fully parallel filter fail to generate for Virtex-4?
This bug occurs only for single and interpolating half-band fully parallel filter structures, when the following conditions are met:
Single Rate - clock frequency / channels = sample rate and channels * num coefficients >1089
Interpolation - clock frequency / channels = sample rate*rate and channels * (num coefficients / rate ) > 1089
There are ways to work around this issue. To retain the half-band structure optimization, the sample frequency must be halved or the clock frequency doubled. To maintain the desired sample and clock frequencies, you must select an alternative coefficient structure, such as single-rate symmetric structure instead of single-rate half-band, or non-symmetric interpolation structure instead of interpolating halfband; however, this will result in a filter implementation requiring significantly more resources than would be expected from the original optimized structure.
This issue will be addressed in the next release.