I need a fully differential amplifier with a 2V p-p output swing in 6ns, can I use the THS4521?

If you require 2V peak-to-peak in 6ns, it is possible to use the THS4521 FDA device. The only caveat is that the THS4521 requires a supply voltage of at least +/-1.65V (or 3.3V single-supply) to achieve such performance. Attached are results from testing the THS4521 with a differential input signal (a single-ended input can be used as well).

This part's performance is highly dependent on supply voltage - please see Table 3 on p. 26 of the THS4521 data sheet for more information.

Best regards,
Ian Williams