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 V_ce 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(G_p) of 6.71dB is achieved when SiGe HBTs operate at frequency of 900 MHz and V_ce 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.