Transistor Switching Analysis∗

With the widespread application of junction transistors in switching applications, the need for a general method of analysis useful in the region of collector voltage saturation has become apparent. Linear equivalent circuits using lumped elements have long been used for small signal calculations of normally-biased transistors, but a comparable method for saturated transistors has been lacking. Recently, Linvill [3] proposed the method of lumped models which allow the analysis of complex switching problems with the ease of linear circuit calculations. The method is shown to be equivalent to a well-known linear equivalent circuit under normal bias conditions. Examples of the application of the method and the use of approximations are drawn from practical circuit problems. Emphasis is placed upon the understanding of the physical phenomena involved, a necessary prerequisite to intelligent circuit design.