RF Power Amplifier Design
Oscillation is frequently a result of inadvertent coupling in the layout. A stability analysis of your design could tell you whether to expect oscillation with the chosen input and output terminations.

Cree provides a CGH40010-AMP demo board whose datasheet includes a schematic diagram and working layout. Though optimized for 3.7GHz, the input and output networks can be adapted for 2GHz operation using the provided device S-parameters.

The datasheet does not mention the amplifier's class of operation; you should be able to determine that from inspection of the output network topology. The >70% peak drain efficiency at 3.7GHz indicates that the conduction angle must be less than 180-degrees.