Local extraction of base and thermal resistance of bipolar transistors

We extend the category of parameter extraction methods that utilize weak avalanche under fixed emitter current conditions to extract base resistance. Our new method consistently accounts for self-heating and Early effect so as to arrive at an accurate extraction of both base and thermal resistance. It involves only small variations in bias and temperature conditions, so that parameter extraction as a function of bias and temperature is enabled. The method is directly applicable to transistors - no dedicated test structures are needed - so that the method is cost effective. The method is demonstrated on RF SiGe HBTs.