If you want to get out an overview on the research subjects of rf CMOS, you can refer to THE IEEE JOURNAL OF SOLIDSTATE CIRCUITS.
The main topics are clustered around the front end of advanced rf communication systems of the mobile communication standards.
Yes one of the main topics on rf ic design is the power amplifier among other building blocks of the front end such as mixers, synthesizers, filters, LNA and data converters for rf applications. The target is to integrate the whole transceiver on one chip for system on chip implementations.