Trade-offs in RF Performance and Electrothermal Ruggedness of Multifinger SiGe Power Cells

In this contribution we analyze the trade-offs existing between the RF performances and the thermal ruggedness of SiGe power multifinger HBTs. Six structures with constant emitter area and different emitter geometry are considered. Small signal S-parameters as well as large signal load-pull measurements are performed to evaluate the effect of emitter geometry on the device RF performances. Moreover, the structures are analyzed through an in house developed electrothermal simulator in order to define the layout influence on the safe operating area (SOA). Finally, some guidelines are drawn to help the designer in trading electrical performances for thermal ruggedness