Hi,
I don't know where you are going to put this amp. I mean at the input or output of the PLL.
You can use a simple common source amp with current source load.
Lets say your supply voltage=1.2v
Design your amp such that the current source takes 0.1 Vdsat and the input device takes 0.1 Vdsat. So the output can swing is 1.2-0.1-0.1=1v(i.e is it can swing from 0.1V to 1.1V). Your output common mode voltage has to be 0.6V(may be you need to use a CMFB to set your Vocm to 0.6v). Now coming to your input, if your Vicm=0.6V , then you can go from 0.2v to 1v. But I am telling you, your output will have harmonic components along with your sine output(Because of large input signal). You can use linearization techniques like resistive degeneration but this creates headroom. So Try different circuits.
I hope this helps you.
Thanks