Module 2: Part 1

The Bipolar Junction Transistor

Learning Objectives

After studying this module, the reader should have the ability to: Understand and describe the general current-voltage characteristics

for both the npn and pnp bipolar transistors. Define the four modes of operation of a bipolar transistor. Apply the piecewise linear model to the dc analysis and design of

various bipolar transistor circuits, including the understanding of the load line.

Qualitatively understand how a transistor circuit can be used to switch currents and voltages, to perform digital logic functions, and to amplify time-varying signals.

Design the dc biasing of a transistor circuit to achieve specified dc currents and voltages, and to stabilize the Q-point against transistor parameter variations

Apply the dc analysis and design techniques to multistage transistor circuits.

Common-emitter circuits: (a) with an npn transistor, (b) with a pnp transistor, and (c) with a pnp transistor biased with a positive voltage source

Transistor current-voltage characteristics of the common-emitter circuit

(a) Common-emitter circuit with an npn transistor and (b) dc equivalent circuit, with piecewise linear parameters

Circuit for Example 3.3

Circuit for Example 3.4

(a) base-emitter junction characteristics and the input load line and (b) common- emitter transistor characteristics and the collector-emitter load line

Circuit for Example 3.5

Circuit for Example 3.6

Circuit for Example 3.8

(a) A bipolar inverter used as an amplifier; (b) the inverter voltage transfer characteristics

(a) The inverter circuit with both a dc and an ac input signal; (b) the dc voltage transfer characteristics, Q-point, and sinusoidal input and output signals; (c) the transfer characteristics showing improper dc biasing

(a) A common-emitter circuit with an emitter resistor and voltage divider bias circuit in the base; (b) the dc circuit with a Thevenin equivalent base circuit