G. Rizzoni, Principles and Applications of Electrical Engineering
Problem solutions, Chapter 8
8.1
Chapter 8 Instructor Notes
Chapter 8 introduces the notion of integrated circuit electronics through the most common building
block of electronic instrumentation, the operational amplifier.
This is, in practice, the area of modern
electronics that is most likely to be encountered by a practicing non-electrical engineer.
Thus, the aim of
the chapter is to present a fairly complete functional description of the operational amplifier, including a
discussion of the principal limitations of the op-amp and of the effects of these limitations on the
performance of op-amp circuits employed in measuring instruments and in signal conditioning circuits.
The material presented in this chapter lends itself particularly well to a series of laboratory experiments
(see for example
1
), which can be tied to the lecture material quite readily.
After a brief introduction, in which ideal amplifier characteristics are discussed, open- and closed- loop
models of the op-amp are presented in section 8.2; the use of these models is illustrated by application of
the basic circuit analysis methods of Chapters 2 and 3. Thus, the Instructor who deems it appropriate can
cover the first two sections in conjunction with the circuit analysis material.
A brief, intuitive discussion of
feedback is also presented to explain some of the properties of the op-amp in a closed-loop configuration.
The closed-loop models include a fairly detailed introduction to the inverting, non-inverting and differential
amplifier circuits; however, the ultimate aim of this section is to ensure that the student is capable of
recognizing each of these three configurations, so as to be able to quickly determine the closed loop gain of
practical amplifier circuits, summarized in Table 8.1 (p. 402).
The section is sprinkled with various
practical examples, introducing practical op-amp circuits that are actually used in practical instruments,
including the summing amplifier (p. 938), the voltage follower (p. 400)), a differential amplifier (
Focus on
Measurements: Electrocardiogram (EKG)
Amplifier, pp. 402-404
),
the instrumentation amplifier (pp. 404-
405), the level shifter (p.406), and a transducer calibration circuit (
Focus on Measurements: Sensor
calibration circuit
, pp. 407-409
).
Two features, new in the third edition, will assist the instructor in
introducing practical design considerations: the box
Practical Op-Amp Design Considerations
(p. 410)
illustrates some standard design procedures, providing an introduction to a later section on op-amp
limitations; the box
Focus on Methodology: Using Op-amp Data Sheets
(pp. 410-412) illustrates the use of
device data sheets for two common op-amps.
The use of Device Data Sheets is introduced in this chapter
for the first time.
In a survey course, the first two sections might be sufficient to introduce the device.