900 MHz 7.4 W SiGe heterojunction bipolar transistor

The SiGe heterojunction bipolar transistor (HBT) suitable for microwave power applications was fabricated by a simple planar process compatible with Si process. The current gain of the SiGe HBT is 70, and the breakdown voltages of the collector junction and emitter junction are about 28 V and 5 V respectively. In common emitter configuration and class C operation, the SiGe HBT with continuous wave output power of 7.4 W and power added efficiency of 53% and power gain of 8.7 dB was obtained at the frequency of 900 MHz. Hence, the emitter current linear density of the SiGe HBT with emitter region width of 6 /spl mu/m is 1.7 A/cm.