Note: This paper is an html adaptation
for posting on the Internet of the original paper presented during
a talk at a UAB student IEEE meeting in the Fall of 1994. As time
permits I will be making a few revisions and additions to this
Much more complicated than is generally
credited, design is not some magical brew concocted by a witch
doctor. Design is a calculated application of scientific knowledge,
intelligence, judgment, and creativity. This paper describes the
process of design from both scientific and philosophical perspectives.
The intent is to direct the beginning designer down the right
path towards becoming a true designer. But first, a foundation
in the basics of design needs to be built. Although this paper
is written for electronic engineers the concepts are general to
The Two Types of Design
is the very common practice of analyzing an existing design to
learn how to adapt the design to a different circumstance. This
process is also known as reverse-engineering and is an excellent
way for new designers to learn the design process. Note that analysis
alone will not reveal the judgment of the original designer. This
can only be resurrected by going through the design process and
applying extensive creativity. Design begins with the difficult
process of inverting the analysis to determine the design equations.
The new designer then uses creativity to determine the plausible
judgments the original designer must have used. Only after this
process is the new designer able to make the appropriate changes
to the original design to make it suitable for a different circumstance.
is a function of creativity, judgment, intelligence, and knowledge.
Original-design is the creation of something out of nothing --
i.e. the first time it has ever been done. The creative skills
required to do original-design come from experience in the re-design
process. Designers may do original-design only a few times during
a career. These occasions are career high points and may earn
the designer a place in engineering history. The original-design
process may be inadvertently used when the designer is unaware
that the design already exists.
The Mathematics of Design
The design process can be represented by a kind of pseudo mathematics to represent the complex functions that must be performed by the designer. There are two basic operators as described below.
Analysis = Design-1.
Analysis is akin to differentiation and is relatively easy. It
takes the knowledge of how to analyze, the intelligence and judgment
to make rational simplifications and some creativity to infer
reasons for the particular implementation. The mathematics has
exactly one solution which is the set of equations that specifies
the performance characteristics of a given set of components.
Just like in calculus where a constant term disappears when
taking a derivative, the judgment in the original design disappears
when doing analysis.
Design = Analysis-1
+ Judgment. Design is
akin to integration and mathematical inversion of the analytic
equations is relatively difficult. The solution is a set of equations
that specify a set of design components to meet specified performance
characteristics. There are usually infinite solutions and considerable
judgment is necessary to choose a best solution for a given application.
The re-design process can be described
The original-design process can be described
Notice that after the initial creativity
the original-design and re-design processes are very similar.
Note also that original-design is an iterative process whereas
the re-design process is not.
The Four Components of Design
Judgment and creativity are two very
important components of design. These two components can only
be performed by human designers -- it is doubtful that computers
will ever take over these functions. Design algorithms are incomplete
without human judgment. The original-design process can not even
get started without human creativity. Knowledge and intelligence
are components of judgment and creativity. Computers are very
good at storing knowledge and to a lesser extent implementing
human guided intelligence. These four components are discussed
below beginning with basic knowledge and concluding with creativity
-- the ultimate in thought process.
Knowledge is simply the accumulation of facts. Knowledge in of itself can do nothing. A book, computer, or human with only knowledge can not make any decisions or accomplish any function. Knowledge is an entity that is easily transferable from one user to another.
is the ability to use knowledge. Thinking is applied intelligence.
Skill is also the application of intelligence. Through intelligence,
one infers complex relationships among pieces of knowledge. These
relationships form the basis of an action to perform for a particular
situation. Intelligence can not be learned -- it only can be refined
by a complex function of experiences both good and bad. Therefore,
intelligence is not a transferable entity.
is a higher form of intelligence. Judgment is the ability to make
good decisions when the knowledge base is incomplete or inaccurate.
Under this situation, basic intelligence alone can not achieve
a conclusion. Through judgment, one infers pieces of knowledge
that are not explicitly known. Intelligence is then used to test
this pseudo knowledge for validity. Like intelligence, judgment
can only can be refined, not transferred. If you can learn from
your (or other's) mistakes then good and bad judgments together
enhance your judgment ability.
is a complex process using knowledge, intelligence, and judgment
to achieve a particular objective. Where as intelligence and judgment
can modify an existing something into something new, creativity
is the ability to transform nothing into something. Through creativity,
one infers both a knowledge and intelligence base and then uses
judgment to check validity. There are many different combinations
of knowledge, intelligence, and judgment to achieve a particular
objective. Creativity does not lend itself to any hard rules or
procedures. Creativity can not be managed -- the greater the
attempt to manage it, the less of it will exist.
General Design Procedure
While different designs will require
different procedures, the following general procedure is intended
to focus on what is important at each step. Exceptions and additions
are made using the judgment of the designer.
Learning to Design
The first step in learning to design
is to analyze the designs of others. You must be proficient in
analysis. Then you must be proficient in the more difficult task
of inverting the analytic equations to produce design equations.
Then you must possess sufficient knowledge, intelligence, judgment,
and creativity to establish the basis for choosing the best solution
of the design equations to a particular circumstance. After you
are proficient at these tasks, you are ready to perform original
There are some common misconceptions
about design. Design is not copying a circuit out of some electronics
made simple book, a magazine article, or an application note.
Any non-engineer such as a hobbyist, technician, or engineering-technologist
can do that. Design is also not just the result of some algorithm
or computer program. Computer programs do not have intelligence
much less judgment. Only a competent designer has that. Computers,
though, can be a tremendous aid to a qualified user.
Design techniques can be shown and practiced
but it takes much more than knowledge of a few techniques to be
an true designer. Becoming a true designer is a long process that
involves considerable individual study of many things, observation
and study of the techniques of an experienced designer (even better
if you are fortunate enough to be an apprentice to one), and many
experiences both good and bad. Any short cut will result in your
becoming another pseudo designer. The problem with pseudo designers
is that they do not know enough about what they are doing to realize
their ignorance. Thinking they already know it all, they have
difficulty learning something new. The beginning designer must
be able to distinguish pseudo designers from true designers and
learn the right lessons from the true designers and not be corrupted
by the pseudo designers. The following humorous illustrations
should help point out the difference.
Skip the design process and go straight to implementation. Implementation
is more fun (and easier) than the design process. Implementation
is what you learn in school.
True designer: Is horrified to skip the design process; knows that time saved in skipping the design process will spent many times over in the debug phase where it is too late to do it right.
The "More is better" syndrome. The pseudo designer uses
what is assumed to be massive overkill to make up for lack of
analysis and ability. The pseudo designer does not comprehend
that there could be negative consequences of overdoing something.
True designer: Calculates what is really needed and strives to implement just that; Uses a calculated margin of safety instead of assumed overkill.
Either does not realize that a mistake has been made or learns
the wrong lesson from a mistake.
True designer: Makes mistakes but recognizes and learns from them.
The "Engineer by fear" syndrome. The pseudo designer
will include things in pseudo-designs that have no relevance other
than to appease various gods of the unknown whose wrath the pseudo
designer is trying to avoid. The pseudo designer is trying to
mask inability by mimicking things that others have been observed
doing, but without understanding.
True designer: Can explain why every component is in a circuit or system and can explain why each component is a particular value. If the true designer is concerned that the circuit or system needs protection from something, then the extent of that something is determined and then designs in calculated protection. The true designer is horrified to leave something to chance. Otherwise the true designer does not waste time including extra junk in a design.
The "Gut feeling supersedes any analysis" syndrome.
The pseudo designer is confident that gut feeling is the optimum
solution to a problem. It is clear then, that the pseudo designer's
brains are in the intestines.
True designer: Has gut feelings but knows how to verify or discard them with the appropriate analysis.
Pseudo designer: Assume that a favorite implementation will achieve the required performance.
True designer: Has favorite implementations but is open-minded to look at appropriate alternatives.
Pseudo designer: Any complexity that the pseudo designer either does not understand or know how to implement is trivial and can be ignored.
True designer: Seeks to gain knowledge in any area where a deficiency is felt. Also seeks the advice and leadership of someone who is proficient.
Pseudo designer: The "I can hide my ignorance by doubting you" syndrome. The pseudo designer does not want own ignorance to be found out and will use doubt to infer knowledge as much or more than the true designer.
True designer: Does not doubt someone unless there is a scientific basis for doubt. Can also identify what would be generally required to clear the doubt.
Pseudo designer: The "Not invented by me" syndrome. If it is not done exactly the way I would have done it, then it is inferior.
True designer: May like own way better but has no objections if another way works sufficiently well. Recognizes that there are generally many ways to implement something. The true designer does not worry about achieving the ultimate optimum in cases where optimums are very broad.
Pseudo designer: The "instant expert syndrome". The pseudo designer has just heard about something new and is already an expert on the subject.
True designer: Is eager to learn new things but would not make any judgments without consulting an experienced designer on the subject.
Pseudo designer: The pseudo designer thinks of own abilities as having little room to improve and is very happy being unaware of the shortcomings of pseudo designs. Any malfunctions are blamed on the magical nature of science.
True designer: The true designer is aware that own knowledge, intelligence, and judgment are less than perfect and continuously strives to improve. Is concerned that shortcomings may lead to malfunctions later.