Ultra High Frequency (UHF) band is used for GSM communication, satellite systems, television broadcast, frequency hopping radios, software de ned radios using advanced digital modulations. Each and every application would require various speci cations and these modern applications require various frequency bands. In this work, a band selecting uhf class-ab GaN power ampli er with 40 dBm output power is built using a GaN-HEMT transistors and PIN diodes. The power ampli er can be tuned in 1350MHz{2700MHz one-octave frqeuency band, has a maximum gain of 17dB, and a maximum saturated output power of 41 dBm.