A novel transistor model for simulating avalanche-breakdown effects in Si bipolar circuits

A physics-based scalable transistor model is described which allows accurate consideration of avalanche-breakdown effects in bipolar circuit simulation. The three-dimensional model consists of six lumped transistor elements, which are connected via elements of the base and emitter-contact resistance. Analytical relations are given to calculate the elements of this six-transistor model (6TM) for arbitrary emitter dimensions from measured area- and length-specific transistor parameters. As a core of the transistor elements, all kinds of conventional transistor models can be used provided an adequate avalanche current source is implemented between the internal collector and base nodes. The validity of this 6TM has been verified under dc and fast transient conditions by simulations and measurements.