Temperature distribution of HBTs with the effect of heat sink

The effect of heat sink on multi-finger heterojunction bipolar transistors (HBTs) is studied with a modified three-dimensional thermal-electrical model. Simulation result shows that the effectiveness of heat sink could be less than what we expected. However, by arranging the heat sink properly, the cooling capability can be improved significantly. Design of emitter cell is also studied in this paper. 16-finger HBTs with 1-, 2-, and 4-fingers per cell are compared in terms of temperature distribution.