BREAKDOWN VOLTAGE OF HIGH-VOLTAGE BIPOLAR-TRANSISTORS

An empirical expression for open-base bulk breakdown voltage of an epitaxial n+pn-n+ bipolar transistor as a function of collector doping density and common-emitter current gain is useful in the design of the collector region of the transistor. In this paper, analytic expressions for optimal collector doping density and epitaxial layer thickness of high-voltage transistors with a lightly-doped collector are obtained as a function of breakdown voltage subject to a minimum collector resistance. A relation between open-base and open-emitter bulk breakdown voltages is also established in this paper.