Transistor switching-circuit design using the charge-control parameters

The charge-control parameters are introduced by considering the operations of switching on, holding on and switching off a transistor, and a simple figure of merit for a switching transistor is derived. Expressions are derived for the switching times and switching currents to provide the changes of charge required to switch a given current, and approximate expressions are presented which clearly reveal the effects on performance of the various parameters. Some examples of circuit design in terms of a typical transistor specification are then given. Following the design of an Eccles¿Jordan circuit, the ability of the circuit to control a number of compatible gate circuits is discussed. Finally, recommendations on the form of specification for the various parameters are made.