Introductory Analog Electronics Course Incorporating In-Class Team Design
Problems and Multi-team Design Based Laboratories
Dr. Dan Moore
Electrical and Computer Engineering
Rose-Hulman Institute of Technology
Terre Haute, IN 47803
Abstract - A new, single term, introductory analog
electronics course was developed in conjunction with a
major curriculum revision in the Electrical and Computer
Engineering department. A desire to provide greater
student-student interaction and team based design
experiences are two of the underlying themes of the
curriculum revision and of the analog course design.
This paper will present an overview of the course and
provide specific examples of both the in-class projects and
laboratory exercises specifically designed to improve
design and team based performance.
Student
comments/suggestions from both formally solicited surveys
and informal discussions will also be included. The paper
will conclude with recommendations for future
modifications and improvements.
Introduction
The introductory analog electronics course was developed
with three main functional blocks: Lectures, Laboratories,
and Design Problem/Homework Assignments. Each block
was designed to meet the following primary objectives:
7
7
7
7
7
Provide an introduction to, and basic
understanding of diodes, bipolar junction and
field effect transistors, and operational
amplifiers.
Improve individual, team, and group problem
solving and design skills.
Develop techniques and provide opportunities
associated with the design, construction,
testing, and analysis of analog circuits such as
power supplies, amplifiers, and active filters.
Improve both oral and written communication
skills.
Improve understanding of the “design process”
and provide opportunities to develop designs
using this design process.
The utilization of in-class team design exercises and
multi-team laboratory design projects as an integral part of
the developed course was one of the methods used to meet
these objectives. Copies of the in-class and laboratory
projects are available as part of the electronic version of the
paper as well as via the world wide web
at http://rose-hulman.edu/~moore1/FIE_97.
Overview
The introductory analog electronics course is designed to be
a single quarter, junior level course required for electrical
engineering majors. The ten week course consists of 3
lecture sessions per week (50 minutes/session) and an
integral 3 hour per week lab. In addition to the general
sophomore engineering courses, the students have
completed a one quarter class in basic circuit analysis and a
one quarter course in electronic modeling concepts and
techniques. The material coverage for this course includes
theoretical concepts, operational characteristics, and basic
applications for pn diodes, bipolar and field effect
transistors, and operational amplifiers. Circuit analysis,
design, and synthesis are emphasized throughout the course
as essential components in the overall design of electronic
systems. The students all have personal laptop computers
with various analysis tools including PSpice. Analog and
simple digital applications are presented for each studied
device as part of the lecture segment. The primary focus of
the in-class exercises and laboratory projects is on analog
circuits and systems.
This is the final required
circuit/device course in the electrical engineering program.
The importance of both oral and written
communications in complete designs is another major
concept emphasized, in addition to the device based
material, and, as such, is integrated throughout the course.
The students are provided with opportunities for short,
informal oral and written presentations in conjunction with
the in-class exercises and initial laboratory projects. Two
formal presentations, both oral and written, are required for
the final two laboratory design projects. Feedback for the
oral presentations is provided by both the instructor and the
presenters’ classmates.
In-Class Exercises
The in-class exercises were planned to be completed during
a normal 50 minute lecture period. Each of the 6 exercises
was designed to be completed in 30 minutes by groups of 5
or 6 people with the remaining class time being used for
informal oral presentations by a spokesperson from each
group. Each team was also required to provide a “memo”
type document to summarize their design solution and/or
“discoveries”.
The first exercise, the only one not design based, was
completed during the first class meeting. The activity was
designed as a “refresher” for the material from the
prerequisite courses and consisted of 5 short problems. The
instructions stated: “The primary task is to correctly answer
as many questions as possible in the 15 minutes allocated.
Remember you are not working as an individual but as part
of a team, try and allocate your “resources” accordingly.”
One of the primary objectives of the exercise was to
illustrate the benefit of distributing the work load. While
the individual questions were not difficult, the probability of
the group answering all 5 was very low unless they divided
the questions among the group. None of the groups
answered all the questions, yet verbal feedback indicated
that most participants felt it was a very good learning
activity especially in terms of group problem solving skills
and approaches.
The other 5 exercises were design based and focused on
the specific device being studied at the time. The students
were assigned to specific groups at the start of the period
and provided with a design scenario. All the design
scenarios were not specified completely so the groups had to
make several assumptions in addressing the problem. They
then had to justify their assumptions in both the oral and
written presentations. The students were told that the
exercise evaluations (grades) were based more on the
“design process”, group dynamics, and “creativity” than on
a “correct” solution. The “most likely” or “best” design
solution would involve the device under study but the
groups were not restricted in the various components they
could use. The groups were told they could use different
devices as long as they justified the change from any
devices identified in the specification.
The first “design” problem involved the design of an
adjustable voltage clamping type system and is typical of the
types of scenarios used in each of the exercises. The
problem was stated as follows:
A customer has requested a circuit that can be
used in conjunction with a new communication
system they are investigating. They would like to
be able to clamp (reference) an input signal to a
user adjustable voltage of between ± 10 V. The
input signal may contain both an AC and DC
component. The output signal should only
contain the AC portion of the input with the
signal referenced to the user selected value. The
user should be able to clamp either the positive or
negative peak of the AC portion of the input
signal.
Your design should use “off the shelf” type
components, require as few components as
possible, no more then two power supplies, and
be easy to construct. The user should not have to
reconstruct the circuit in order to change the
clamped voltage or to select the positive or
negative reference peak. You may assume the
input signal is repetitive and that you may use up
to 5 cycles to obtain the desired output signal
after the user selects the parameters.
Each team was given the chance to “sell” their solution
to the class during the oral presentation portion of the
exercise.
The BJT and FET based activities allowed the groups to
choose between an analog and digital design problem. The
in-class operational-amplifier problem involved the design
of a bandpass and a bandreject filter. The final exercise was
based on the design of an integrated amplifier using current
sources for biasing and active loads.
Laboratory Projects
There were 7 laboratory projects over the 10 week
quarter. The first 5 were designed for a single laboratory
period, the sixth for a two week period and the 7th for three
weeks. All lab projects were design based and included oral
presentations, written documentation, computer based
analysis of the final design, and fabrication and testing of
the final design solution. The students were allowed to
form their own two or three person teams during the first
lab period. These teams remained constant for the entire
quarter in contrast to the in-class groups which were
changed for each in-class exercise. Multiple teams were
combined for the later laboratory projects. The individual
laboratory projects were posted electronically approximately
one week before the associated scheduled lab, with a hard
copy being made available approximately 2 days later.
The first two projects were based on designing simple
test circuits for determining the characteristics of diodes
(lab 1) and BJTs (lab 2). The teams were required to
provide a written test procedure for their test circuit and to
provide a 5 minute oral overview of their design. The test
procedures and “unknown” diodes or BJTs were then
randomly distributed to at least one volunteer from each
team. These volunteers were then required to follow the test
procedure and determine the characteristic of their
unknown device using the circuitry designed by the team
whose test procedure they were following. An evaluation of
the procedure and test circuit was then prepared by the
volunteer “tester”. The team being “tested” also provided
an evaluation of the volunteer in terms of understanding,
test skills, and ability to follow instructions. These
evaluations were provided to the associated teams at the end
of the period.
There appeared to be a significant
improvement in the written procedures between the first and
second laboratory project as a result of the feedback from
the first lab.
The third lab period focused on the “design process”
and included an “active participation” lecture for the first
30 minutes followed by an actual design exercise. The
design problem was not supplied until after the lecture
portion of the lab period. The student teams were given the
following design problem:
A customer requires a voltage test device to
help indicate approximate ranges of voltages.
The total voltage range is between - 5 and + 10
V. The desire is to have a visual indication using
LEDs. The customer would like to have an LED,
or combination of LEDs, to indicate four
different ranges. Range 1 between -2 and - 5 V,
range 2 is between -1 and 2 V, range three is
between 2.5 and 5 V, and range four is above 5
V. Your design should be limited to parts readily
available at the customer’s plant -- BJTs, red and
green LEDs, diodes and resistors.
The teams were then given an hour to develop a
possible solution, or solutions, and to prepare a short oral
and written justification of their solution(s). The teams
were encouraged to simulate their designs using PSpice as
well. Each team was given 10 minutes to present and “sell”
their design(s) and demonstrate their system operation if
possible. The other teams were encouraged to ask questions
following the oral presentation.
The 4th and 5th projects involved various amplifier
design scenarios and were completed by the individual
teams.
The 6th project was designed to cover two weeks and
involved the design of a three “stage” amplifier consisting
of a high input impedance input stage, an output stage
capable of supplying a ± 5 V symmetric voltage swing
across a 100 : load, and a middle “stage” necessary to
produce an overall system voltage gain of 20 ± 3 dB
between 150 Hz and 20 kHz. The individual teams were
formed into project groups consisting of three teams. Each
project group had to complete the project within the allotted
time period by assigning one of the “stages” to each of the
smaller teams.
The groups were then given the
“opportunity” to make a formal oral presentation and
demonstration to the potential customer -- the instructor and
other students. The primary goal of this project assignment
was to help the individual teams develop the skills
necessary to work with other groups in order to develop an
overall system. The actual amplifier design was fairly
straightforward but could not include operationalamplifiers.
The final laboratory project spanned three weeks and
involved project groups consisting of 5 sub-teams. Again,
the project groups were required to prepare a formal
presentation and demonstration of their design by the third
week. The project “request” was to design a system in order
to “extract specific signal information from a complex
signal”. The system was divided into five segments: DC
removal; signal processing; transistor buffer; active
biasing using a current source network; active filter. The
specifications for each segment were left somewhat vague in
order to allow the students the greatest flexibility in their
design.
Again, the groups were then given the
“opportunity” to make a formal oral presentation and
demonstration to the potential customer -- the instructor and
other students.
Student Feedback
Feedback was solicited throughout the course.
This
consisted of both written and verbal comments. The verbal
comments were solicited informally, especially during the
lab periods, and during office visits. The written feedback
was obtained three times during the quarter. The requested
information on the written surveys covered homework, tests,
pop quizzes, oral presentations, in-class exercises, and
laboratory projects. The students were asked to rate each of
the items overall using a 1 - 5 scale and then to provide
specific “pro” and specific “con” comments.
The overwhelming feedback, both verbal and written,
as very positive with a couple of notable exceptions. The
students rated the in-class and laboratory projects very
highly and commented that they felt they really “learned
more/understood better” through these group activities.
The incomplete design specifications was one area with
interesting feedback. On the first written survey, as well as
initial verbal comments, many students felt the design
problems were too difficult and not direct enough. The
opposite was true on the second survey conducted toward
the end of the quarter when a large number of students
stated that they liked the challenge associated with “filling
in the missing parts”. I believe this change can be
attributed to a better understanding by the students of what
was being evaluated and how they were being evaluated.
Once they recognized that I was not grading based on a
“right” design solution, they felt more free to be creative.
The only significant objection related to the in-class
group assignments. The large majority (> 85 %) felt that
the in-class groups should not have been changed for each
exercise. Many recommended changing the groups half
way through the quarter if at all. They believed that their
overall performance and understanding would have been
improved if they did not have to “learn” each others
approaches before they could address the actual design
problem.
One area that was somewhat surprising related to the
evaluation process. The “grade” for the in-class exercises
was based on the group performance -- every member
received the same grade. The laboratory grades were also
based primarily on the overall team or project groups’
performance with less than 10 % based on the specific
individual’s contribution. There were very few students
that even mentioned that they were concerned that “their”
grade depended on the teams’ performance. In discussing it
with students from both ends of the spectrum, it appears
that they believed there were sufficient grading inputs tests, pop quizzes, final exam - to differentiate one student
from another. They seemed to enjoy the fact that the
“group” grade allowed them some flexibility on activity
“input” for any given project.
Conclusions/Suggestions
The overall course was very successful as determined both
by student evaluations/inputs and by the students’ overall
performance on tests and the final exam. The apparent
level of understanding and design capability was very good.
The improvement in the written presentations as the term
progressed was evident not only to the instructor but to the
students as well. The improvement evidence was based on
evaluations, by both the student teams and the instructor, of
some of the written test procedures and operating “guides”.
The use of the in-class exercises is the only area that I
believe needs a major adjustment. I would recommend
continuing to assign the in-class groups, as opposed to
allowing them to self select, but would only change them at
the mid-term break. I would also recommend providing the
design specifications on-line one day before the in-class
exercise is scheduled. The use of dual -- analog and digital
-- scenarios is another area of concern. There does not
appear to be any benefit in allowing the groups to select one
of two scenarios, rather it appears to unnecessarily delay
“attacking” the design problem. My recommendation
would be to generally just develop one for each exercise
and/or assign the scenarios if more then one is used.
Readers interested in some specific guidelines and
suggestions for group based activities and cooperative
learning may find “A Handbook on Cooperative Learning”
by Wendy Duncan-Hewitt, David L. Mount, and Dan
Apple to be a good resource [Pacific Crest Software, Inc.,
1995, ISBN 1-878437-22-4]