High-power SiGe heterojunction bipolar transistor (HBT) with multiple emitter fingers
High-power SiGe HBTs with multiple emitter fingers are developed by using interdigitated structure and each emitter stripe area of 3times45 mum2. The value of collector-emitter voltage Vce is carefully selected to ensure these power devices operating at high power levels. Four-Watt RF power with maximum high power-added efficiency (PAE) of 49% and power gain(Gp) of 6.71dB is achieved when SiGe HBTs operate at frequency of 900 MHz and Vce of 12V. The devices have emitter power linear density achieved as high as 1.47W/mm and the RF power density is 1.6W/mum2. The power performance of these devices under different bias conditions are also studied. These results set a benchmark for high power performance of the devices and show the great potential of SiGe HBTs for RF high-power amplifications.