I'm currently using the 4 LVPECL outputs of an ad9510 to simultaneously clock 4 ADCs. It's a ratiometric measurement, so the most important clocking parameter is the differential jitter between the 4 channels. I don't think this characterstic is spec'd but it seems to be under 1 ps.
I would like to modify the design to use an ad9520. Does anyone know how the jitter specs, specifically differential jitter, compares to the ad9510?