Improving parasitic emitter resistance determination methods for advanced SiGe:C HBT transistors

Determination methods for the emitter resistance of bipolar transistors are reviewed and evaluated with respect to the constraints introduced by modern SiGe:C HBT processes with f_MAX reaching 500GHz [1]. Maximum transistor performance is obtained at ever higher current densities, involving huge self-heating effect which dramatically degrades the accuracy of existing methods. A new parameter extraction procedure is presented and compared to existing solutions. Finally, a simple methodology to correct self-heating effects is proposed, which advantageously increases the accuracy of emitter resistance determination under high self-heating conditions.