I am interested in using the ADRF6510 filter component on the baseband of a SDR. It has generally very good specifications, but one of the most important ones for a SDR is completely unsuitable. The gain-flatness can be up to several hundred ns because of the Butterworth filter choice. This makes the part completely useless for nearly all radio applications. SDRs generally require no more than a few ns of group delay.
Is it possible that a Bessel version of the part would be possible? That would make the component suitable for use in a SDR.