Learning Outcomes:

● Be able to determine the dc levels for the variety of important BJT configurations.
● Understand how to measure the important voltage levels of a BJT transistor configuration and use them to determine whether the network is operating properly.
● Become aware of the saturation and cutoff conditions of a BJT network and the expected voltage and current levels established by each condition.
● Be able to perform a load-line analysis of the most common BJT configurations.
● Become acquainted with the design process for BJT amplifiers.
● Understand the basic operation of transistor switching networks.
● Begin to understand the troubleshooting process as applied to BJT configurations.
● Develop a sense for the stability factors of a BJT configuration and how they affect its operation due to changes in specific characteristics and environmental changes.

The analysis or design of a transistor amplifier requires a knowledge of both the dc and the ac response of the system. Too often it is assumed that the transistor is a magical device that can raise the level of the applied ac input without the assistance of an external energy source. In actuality, The analysis or design of any electronic amplifier therefore has two components: a dc and an ac portion. Fortunately, the superposition theorem is applicable, and the investigation of the dc conditions can be totally separated from the ac response. However, one must keep in mind that during the design or synthesis stage the choice of parameters for the required dc levels will affect the ac response, and vice versa.
The dc level of operation of a transistor is controlled by a number of factors, including the range of possible operating points on the device characteristics. In Section 4.2 we specify the range for the bipolar junction transistor (BJT) amplifier. Once the desired dc current and voltage levels have been defined, a network must be constructed that will establish the desired operating point. A number of these networks are analyzed in this chapter. Each design will also determine the stability of the system, that is, how sensitive the system is to temperature variations, another topic to be investigated in a later section of this chapter.

Lesson Plan:

Lecture 01: Operating Point and Fixed-Bias Configuration

Lecture 02: Emitter-Bias Configuration and Voltage-Divider Bias Configuration

Lecture 03: Collector Feedback Configuration and Emitter-Follower Configuration

Lecture 04: Common-Base Configuration and Miscellaneous Bias Configurations

Lecture 05: Design Operations and Multiple BJT Networks

Lecture 06: Current Mirrors and Current Source Circuits