Design of multi-finger HBTs with a thermal-electrical model

Abstract Multi-finger heterojunction bipolar transistors (HBTs) with uniform spacing exhibit a higher temperature at the center of devices. The temperature distribution on the emitter fingers of the HBT is studied with a three-dimensional thermal–electrical model. Using this model, multi-finger HBTs are designed with non-uniform spacing to improve temperature distribution. Depending on the number of emitter fingers, different design approaches are demonstrated. For a six-finger or 12-finger HBT, the design is more straightforward. For a complex structure such as a 26-finger HBT, an efficient design procedure is necessary. In all of these cases, the calculated results show significant temperature reduction on non-uniform spacing devices.