Keysight's Advanced Design System users, what's wrong with this simulation?
If you look at your MOSFET's datasheet page 2 (like @PlasmaHH proposed above).

You'll see that it is not able to work properly at 1 GHz since it's turn-on and turn-off delay times are about tens of ns which obviously waaaay too slow to operate at this frequency. You should try with a component better suited for RF applications (or just decrease your operating frequency).