Andrei Grebennikov - RF and Microwave Power Amplifier Design, McGraw-Hill Professional Engineering
Steve C. Cripps - Advanced Techniques in RF Power Amplifier Design, Artech House
Peter B. Kenington - High Linearity RF Amplifier Design, Artech House
You may also search Amazon.com for additional books. (Also try Artech House's web page https://www.artechhouse.com - They have many very good books on Microwave and RF engineering)