Electrothermal behavior of highly-symmetric three-finger bipolar transistors

Design guidelines are established for improving the electrothermal stability of multifinger bipolar transistors as a result of experiments and simulations conducted on three-finger silicon-on-glass BJTs with selfheating and mutual thermal resistances varying over a large range of values, depending on silicon area, presence of heatspreaders, isolation and distance between the fingers. A rotational-symmetric topography that ensures a high level of symmetry between the individual emitters is proposed to achieve a significant enlargement of the safe operating area as compared to the more conventional parallel-finger designs.