Download Section C The Bipolar Junction Transistor (BJT) (Chapter 4 of your text)

Section C
The Bipolar Junction Transistor (BJT)
(Chapter 4 of your text)
Section C1: Introduction & Goals
The bipolar junction transistor (BJT) is the first three-terminal active
device that we’re going to discuss. In this section, we’re going to discover
the basic principles of transistor operation – that is, how a voltage across or
a current through two terminals of the transistor control the voltage or
current of the third terminal. Using this characteristic, the transistor may be
used as a controlled, or dependent, source. These characteristics allow the
transistor to be used in a wide variety of applications, from amplification of
signals, to analog and digital logic and memory circuits.
Upon completion of this section of our studies in this section, our goals are
for you to be familiar with:
¾ the basic structure of the BJT, its relationship to the semiconductor diode
and the fundamental physical characteristics and modes of operation for
this device;
¾ the distinction between large and small-signal operation and common
device models for each operational range;
¾ analysis techniques for device operation under a variety of input
conditions, to include: mathematical, graphical and computer simulation;
¾ fundamental operation and design considerations for single-stage BJT
amplifier configurations; and
¾ biasing considerations and techniques for optimal single-stage amplifier
output.
I would like to caution you to be patient with yourself in this section.
In many ways, this is the most difficult material we’re going to be
dealing with – we’re going to go from our nice, safe world of twoterminal, mostly linear devices to an entity that is much more
complex (and much more useful!).
We’re going to start by going back to the physics of semiconductors,
so if you’re uncomfortable you may want to review the discussions
of pn junctions and biasing…yet one more time…