Hello, are there any clock generation evaluation boards that has signed-ended outputs? All of those I found has only differential outputs.
Keep in mind that you will not be able to output 1GHz using CMOS and LVPECL is better than LVDS for high frequencies. The AD9520 has LVPECL outputs with a max output frequency of 2.4GHz. The AD9520 has a few versions that span different VCO ranges. I would recommend the AD9520-3 which has a VCO center frequency of 2 GHz (which can easily be divided by 2).
In terms of the long-term (year) output frequency stability, can I assume that will be determined by the reference clock and not the PLL or anything on the AD9520?
Yes the main factor for frequency stability will be the stability of the reference.
One last question, what are the differences between AD9520 and AD9522?
The AD9520 has LVPECL/CMOS outputs and the AD9522 has LVDS/CMOS outputs.
You can download the evaluation board software and use it in "offline" mode to familiarize yourself with the part and make sure it works for your setup.