CHAPTER 17 - Valves and Transistors as Circuit Elements

Abstract

This chapter discusses valves and transistors as circuit elements. There are three distinct types of problem concerning the behaviour of triodes in circuits: (1) those in which the a.c. signals move the instantaneous operating point of the valve through such a wide range of values that it is not possible to consider the characteristics as linear; (2) problems in which, although the a.c. signals are small, the d.c. operating point is located in a nonlinear part of the characteristic such as in modulation and detection circuits; and (3) operation in the linear part of the characteristic with signals small enough not to drive the valve beyond the limits of linearity. There is a low-frequency physical model of the common base transistor in which each element has a physical interpretation and the values of each element can be calculated in terms of physical processes. The model has two active dependent generators and is too complicated for use in circuit analysis.