I'm in the early stages of designing a board with a Virtex-4 FX on it which we are planning to use for development involving RocketIO. The other guys on the team have stated that it would be "really useful" to have the clock for the RocketIO fed from a programmable oscillator. We have a Virtex-II FX development board that has a similar arrangement, using a ICS8442 low jitter LVDS frequency synthesizer. Does anyone have any suggestions or advice? Can/Should I use the same device? Is this a wild goose chase?