Rules for Determining the State of a Bipolar Junction Transistor

Abstract

In pulse and digital electronics the bipolar junction transistor (BJT) may be in saturation, cut-off, active, or reverse (inverse) active states. In addition, the BJT may change states as voltages and currents change with time. Analysis and design can often become challenging and frustrating for the undergraduate student who has not yet developed intuitive insight into the subject matter. In this paper logical and systematic rules for determining the state of a BJT are presented to simplify the circuit analysis, ease the frustration, and help the student develop physical insight into the design and analysis of electronic circuits.