Patent ID: 6931345

Claim:
A method for quantifying a plurality of safe operating regions within a safe operating area (SOA) for a bipolar junction transistor (BJT), comprising: providing a current mirror circuit with mutually coupled first and second BJTs, wherein said first BJT includes a base electrode, a collector electrode and an emitter electrode with an area, said second BJT includes a base electrode, a collector electrode and an emitter electrode with an area, and said second BJT emitter area is greater than said first BJT emitter area; applying an inter-electrode voltage with a plurality of values to first and second ones of said second BJT electrodes; applying a first current with a plurality of values to at least one of said first BJT electrodes; measuring a plurality of values of a second current through one of said second BJT electrodes corresponding to a plurality of combinations of said pluralities of inter-electrode voltage and first current values; computing a plurality of electrode current densities corresponding to a plurality of ratios of said plurality of second current values and said second BJT emitter electrode area; computing a plurality of ratios of said second and first current values corresponding to at least a portion of said plurality of combinations of said pluralities of inter-electrode voltage and first current values; computing a plurality of ratio errors corresponding to a plurality of differences between each one of said plurality of second and first current ratios and a reference current ratio; and generating a plurality of contours corresponding to said plurality of electrode current densities as functions of said plurality of inter-electrode voltage values for said plurality of ratio errors.