The high power properties of heterojunction FETs (H-FET) have been investigated. The H-FETs are fabricated by using a strained AlGaAs/GaInAs/GaAs/AlGaAs selectively-doped double heterojunction structure. As compared with GaAs MESFETs, the H-FETs show 1.5 dB higher saturation power and 8% higher power-added efficiency than those of the MESFETs, at 950 MHz and 4.7 V. The H-FETs are more suitable for the power amplifier of cellular telephones.