文档介绍：Page 1 Tuesday, May 27, 2003 10:21 PM
CHAPTER 5
Bipolar Junction
Transistors (BJTs)
Introduction 000 Single-Stage BJT Amplifiers 000
Device Structure and The BJT Internal Capacitances
Physical Operation 000 and High-Frequency Model 000
Current-Voltage Frequency Response of the
Characteristics mon-Emitter Amplifier 000
The BJT as an Amplifier and The Basic BJT Digital
as a Switch 000 Logic Inverter 000
BJT Circuits at DC 000 The SPICE BJT Model and
Biasing in BJT Amplifier Simulation Examples 000
Circuits 000 Summary 000
Small-Signal Operation and Problems 000
Models 000
INTRODUCTION
In this chapter, we study the other major three-terminal device: the bipolar junction transistor
(BJT). The presentation of the material in this chapter parallels but does not rely on that for
the MOSFET in Chapter 4; thus, if desired, the BJT can be studied before the MOSFET.
Three-terminal devices are far more useful than two-terminal ones, such as the diodes
studied in Chapter 3, because they can be used in a multitude of applications, ranging from
signal amplification to the design of digital logic and memory circuits. The basic principle
involved is the use of the voltage between two terminals to control the current flowing in the
third terminal. In this way, a three-terminal device can be used to realize a controlled source,
which as we learned in Chapter 1 is the basis for amplifier design. Also, in the extreme, the
control signal can be used to cause the current in the third terminal to change from zero to
a large value, thus allowing the device to act as a switch. As we learned also in Chapter 1,
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2 CHAPTER 5 BIPOLAR JUNCTION TRANSISTORS (BJTs)
the switch is the basis for the realization of the logic inverter, the basic element of digital
circuits.
The invention of the BJT in 1948 at the Bell Tel