to Teaching Design with Standard Components
J. Joseph
Oral Roberts University
Tulsa, Oklahoma 74171
Abstract - This paper describes the structure of a course that
has been created to help electrical engineering seniors with
design. It is expected to make the transition to the capstone
design almost effortless. Students take this course after
having taken several theoretical courses in the areas of
digital signal processing, control theory, electromagnetic
theory and so on. The course does not have written
examinations but real projects. Students are required to use
mathematical and simulation modeling tools before
constructing any end product. Thus the emphasis is not on
designs that are theoretical in nature but on systems that are
physically realized. It begins with
designs
using
operational amplifiers, optimal routing of PCBs and
proceeds to the digital area by studying Verilog HDL
while designing systems using PLAs and FPGAs. Though an
elective, this course has been well received by students.
Introduction
According to ABET, engineering design is the process of
devising a system, component or process to meet desired
needs. It is a decision making process in which the basic
sciences, mathematics and engineering sciences are applied
to optimally convert resources to meet a stated objective.
The course entitled: Design With Standard Components
considers the question of design from the practical aspect of
available components and processes involved in
manufacturing the end product. The focus is on appropriate
use of available components, with their features and
limitations.
Use A/D , D/A converters
Use MicroSim PCBoards [5] and Auto Router
[6] to design printed circuit boards
Use Verilog HDL [3] to program PLDs
Use CUPL [7] to program PLDs
Course Projects
Over the last few years, the projects for the course have
always undergone changes though they contained the
following core projects:
Design of an integrator
Design of a low power audio-amplifier using LM-386
Design of an active filter using operational amplifiers
Design of a LUX meter
Design of a function generator [2] using ICL-8038
Design of power control circuits using SCRs, Triacs
and Power MOSFETs
Design of a traffic light controller using NE-555
Design of a Printed Circuit Board using MicrSim
PCBoards [5] and Autorouter [6]
Design of special purpose circuits using PLDs.
The projects were chosen to help students gain
confidence in designing, constructing and testing of systems
according to given specifications. A variety of topics are
discussed in the lectures. The topics may also include those
that are specially requested by students who want to apply
them in their senior projects. As a specific example,
MicrSim PCBoards [5] and Autorouter [6] are not
discussed in any other theoretical course while it is covered
in this course. Hence this course helps students gain
confidence in the art of design.
Course Goals
Course Topics
As a result of successfully completing the course, students
will be able to:
Select proper components to meet specified
objectives
Minimize electrical noise in circuits
Anticipate and avoid problems of stray signals
through the use of proper grounding and shielding
Learn to design power circuits using SCRs, Triacs
and Power MOSFETs
Make most of SSI, MSI and LSI packages in the
design process
General concepts of Operational Amplifiers
Ideal Operational Amplifiers
Comparators, Oscillators and active filters
A/D and D/A circuits
Grounding and shielding
Gate level and data flow modeling techniques
Logic synthesis using Verilog HDL [3]
Learning to use CUPL [7] , PCBoards [5] and
Autorouter [6]
Students learn about the problems associated with
improper grounding and shielding in an otherwise
well designed system. They learn to avoid problems
of stray signals through the use of proper grounding
and shielding
Since ORU. does not have a course in
power/industrial electronics, this course also teaches
them to control a.c. and d.c power circuits using
SCRs, Triacs and Power MOSFETs
Students learn to design circuits using available SSI,
MSI and LSI packages
They learn to condition signals and process them in
either analog or digital form. Students will be able to
go with ease from analog to digital using A/D
converters and from digital to analog using D/A
converters
Students are able to use MicroSim PCBoards [5]
and Router Auto [6] to design printed circuit
boards. They later use these circuit boards in one of
their applications.
They learn the importance of HDL and specifically
Verilog HDL [3]
They design circuits using PLDs and use CUPL
[7] to program the PLDs [4]
Students' perception of engineering changed after
this course. They were able to effectively integrate
theory from various engineering courses and apply
them to realize "well designed" circuits. They learned
about constraints, trade-offs and pit-falls involved in
the process of design. The major outcome of the
course has been the transformation of students from
theoretical designers to practical designers.
Design Phase I
Operational amplifiers being the central elements [1] of
modern linear electronic circuits, phase I focuses on the
design and fabrication of systems having operational
amplifiers. Real operational amplifiers have non-ideal
characteristics which introduce inaccuracies. Hence, students
are taught to take real operational amplifiers and real
components to design real circuits. In addition to the basic
characteristics of operational amplifiers, students are taught
to consider the rated output ( for power operational
amplifiers), power dissipation, supply current drain, transient
response, input capacitance and noise (created by the
amplifier). They also take into account the dependencies of
temperature, frequency, supply voltage, source resistance
and load resistance on operational amplifiers.
Students learn to select passive components. e.g., they
are informed of carbon, wire-wound, metal-film and
carbon-film resistors, different types of potentiometers and
capacitors. They are made aware of real capacitors that have
leakage resistance. For many students, the variety is an eye
opener. They learn the differences in ceramic, mica, film
type and electrolytic capacitors while learning to choose the
capacitors to suit respective applications.
Design Phase II
In this phase students design systems using special purpose
ICs. Projects using NE-555, ICL 8038 are implemented. In
addition to using special purpose ICs, students are made
aware of grounding and shielding. Since few courses cover
topics in grounding and shielding instructions given in this
course will help them design systems that are well grounded
and immune to electric and magnetic fields.
Conclusion
In Phase III, students learn and apply Verilog HDL [3] to
design special purpose ICs with PLDs. They also work with
the commercial package CUPL [7]. Students used
GAL20V8 [4] to complete their projects. It has electrically
erasable floating gate technology with speed performance
far above those required in a typical class room environment.
Teaching design using standard components was discussed.
The methodology used has helped many students gain a
broader understanding of contemporary design techniques.
These design techniques are generally not discussed in many
theoretical courses e.g. Electromagnetic theory, Control
Theory, Circuit Theory, Power Systems etc. On successful
completion of this course, students have little difficulty
completing capstone design projects.
Outcomes of the course
Acknowledgment
Design Phase III
Students learn to choose the right type of passive
components for the application under consideration;
e.g. they learn about carbon-composition resistors,
wire-wound resistors,
metal-film resistors,
carbon-film resistors, thin and thick-film resistors.
Students are made aware of noise in electrical
systems. They learn to choose components that result
in low noise systems.
The author thankfully acknowledges the valuable comments
received from referees and support received from ORU
administration to carry out this work
References
1)
Meiksin, Z.H. and Thackray C. P, "Electronic
Design with Off-the-shelf integrated circuits",
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Prentice-Hall, 1987.
Stanley D William, "Operational Amplifiers With
Linear Integrated Circuits", Merrill, 1996.
Palnitkar Samir, "Verilog HDL", Prentice-Hall,
1996.
"Semiconductor Data Book", Lattice Corp., 1996.
"PCBoards Users Manual", MicroSim Corp.
"Autorouter Users Manual", MicroSim Corp..
"CUPL, Universal Compiler for Programmable
Logic", Logical Devices Inc., 1983.
"Design Lab Users Manual", MicroSim Corp.