High efficiency 1 watt HBT power amplifier with harmonic tuning for mobile communications

GaAlAs-GaAs power HBTs have been investigated for handsets in mobile cellular communication system at 1.8 GHz. Different HBTs operating classes have been compared using a simulated multiharmonic load-pull type optimization. The optimum operating class taking into account the power density and the thermal effect has been discussed. Class F amplifiers using HBTs or GaAs MESFETs have been investigated. An HBT amplifier has been designed and fabricated for DCS 1800. 1 W output power with a power-added efficiency of 50% has been measured.