The AD9083 looks to be very close to being the optimal solution for a problem I'm facing where I need a high density of high speed data conversion. The AD9083 samples at 2Gsps but only has an effective bandwidth of 125MHz. From what I see in the datasheet, this is because it's a delta-sigma converter, and the quantization noise is shaped into this region, degrading SNR by 6dB/octave, and ADI believes 125MHz to be the point at which SNR is degraded below spec.
Is it possible to provide passive gain (low pass filter with high Q-factor) in the 125MHz-250MHz region, thereby preserving the SNR and thus extending the bandwidth? I understand that the serial data output becomes a limit and I'd only be able to use 8 channels outputting 500Msps, but this would still provide the greatest density of data conversion especially for the power.