A Regional Approach for Computer-Aided Transistor Design

A regional approach to transistor design is presented which makes possible the determination of transistor gain hFE for any transistor (doping profile specified) operating at any given values of emitter current IE and collector-to-emitter voltage VCE. This approach extends the classical diffusion theory of transistors to include conductivity modulation, voltage-controlled base motion, and current-controlled base motion (base widening). Due to the simplicity of this technique, time-sharing computer techniques were used. This allowed for user interaction, making this approach very attractive for education as well as design. The regional approach is a likely candidate for satisfying the needs for the device designer (it contains device performance versus doping profile), the circuit designer (it allows determination of equivalent circuit models from knowledge of the electron and hole densities throughout the device), and the academic world (it is simple and physical). It is anticipated that the regional approach will allow engineers to develop a "feel" for transistor behavior under wide ranges of operating conditions.