Recently, small-signal microwave performance has been reported for PNP InAlAsAnGaAs HBTs [I, 21. While power performance of PNP AlGaAs/GaAs HBTs has been demonstrated [ 3 ] , nothing has been reported on power performance of PNP HBTs in the InP material system. In this work, InAlAshGaAs PNP HBTs were fabricated and subsequently characterized under large signal conditions at X-band to determine their suitability for high-frequency power applications. PNP HBTs demonstrated f T and fma* as high as 13 and 35 GHz, respectively. Power performance at 10 GHz was comparable to InP-based NPN single HBTs, providing up to 10 dB of gain, 0.49 rnW/pm2 of output power, and 24% power-added efficiency. Analysis of these HBTs suggests further design and epilayer optimizations for increased power performance.