3.5 V, 1 W high efficiency AlGaAs/GaAs HBTs with collector launcher structure

AlGaAs/GaAs HBTs with collector launcher structure are developed for the low operation voltage power amplifier. We discuss the relationship between the HBT collector structure and its microwave power performance, demonstrating that the launcher structure suppresses the Kirk effect near the saturation region and increases the current handling capability. A fabricated HBT, which has an emitter size of 2 /spl mu/m/spl times/20 /spl mu/m/spl times/32 fingers, exhibits a power added efficiency, /spl eta/add, of 70% with an output power, Pout, of 30 dBm and a power gain, Ga, of 15.7 dB at a supply voltage of 3.5 V and a frequency of 900 MHz. At 2.5 V, Pout is 26.5 dBm, /spl eta/add is 70% and Ga is 14.7 dB. These results demonstrate that HBTs with a collector launcher structure are appropriate for power applications, especially at low voltage operation.<
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