Development of a second breakdown model for bipolar transistors

dc.creatorMenhart, Steve
dc.description.abstractSemiconductor devices are often driven Into operating regions in which conventional models, representing normal regions of operation, are Inadequate. An example of such an operating region is frequently obtained when bipolar transistors are operated as switches in circuits containing inductors. In this case, the transistor may experience large voltages and currents simultaneously. In an actual transistor, the collector-emitter voltage is constrained by avalanche breakdown between the collector and emitter regions; under conditions of breakdown or near-breakdown and high collector current, an instability, known as second breakdown, may occur. This instability often results in catastrophic device failure. The library bipolar transistor model contained within the circuit analysis code, SPICE, is quite sophisticated, within a normal region of transistor operation. However, it does not model either avalanche or second breakdown. Several models, in the form of augmentations to the SPICE transistor model, have been developed in this work- These models permit SPICE to predict accurately voltages and currents associated with the transient response of circuits containing both energy storage elements and active devices, which the standard SPICE code alone is incapable of doing. In this work avalanche breakdown has been modeled in a manner not previously encountered by the author. This model recognizes the interdependence of the two transistor Junctions, with regard to breakdown between the collector and emitter regions. A second breakdown model that previously did not exist, is presented. The concept of a dependent subcircuit is introduced to model second breakdown, in which case the subcircuit also performs diagnostic and controlling functions, as an integral part of the model. A subcircuit such as used in this work to model second breakdown is analogous to an analog computer.
dc.publisherTexas Tech Universityen_US
dc.subjectBipolar transistorsen_US
dc.subjectSwitching circuitsen_US
dc.subjectSemiconductors -- Fluctuations -- Testingen_US
dc.titleDevelopment of a second breakdown model for bipolar transistors
dc.typeDissertation Engineering Tech University


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