Module 1: Part 1 Semiconductor Materials and Diodes

Learning Objectives After studying this module, the reader should have the ability to: Understand the concept of intrinsic carrier concentration, the difference between n-type and p-type materials, and the concept of drift and diffusion currents. Analyze a simple diode circuit using the ideal diode current- voltage characteristics and using the iteration analysis technique. Analyze a diode circuit using the piecewise linear approximation model for the diode. Determine the small-signal characteristics of a diode using the small-signal equivalent circuit. Understand the general characteristics of a solar cell, light- emitting diode, Schottky barrier diode, and Zener diode.

Ideal forward-biased I-V characteristics of pn junction diode, with the current plotted on a log scale for I s = A and n = 1

The ideal diode: (a) I-V characteristics, (b) equivalent circuit under reverse bias, and (c) equivalent circuit in the conducting state

The diode rectifier: (a) circuit, (b) sinusoidal input signal, (c) equivalent circuit for v I > 0, (d) equivalent circuit for v I < 0, and (e) rectified output signal

The diode and load line characteristics for the circuit shown in Figure 1.24

The diode equivalent circuit (a) in the “on” condition when V D  V y, (b) in the “off” condition when V D < V y, and (c) piecewise linear approximation when r f = 0

AC circuit analysis: (a) circuit with combined dc and sinusoidal input voltages, (b) sinusoidal diode current superimposed on the quiescent current, (c) sinusoidal diode voltage superimposed on the quiescent value, and (d) forward-biased diode I-V characteristics with a sinusoidal current and voltage superimposed on the quiescent values