Page 51 - Analog Circuit Design Art, Science, and Personalities

Reflections of a Dinosaur

Ref ormco
Input
Figure 6-1.
Basic digital to
analog converter I
(DAC). DIGITAL
TO 3
AnalOQ
ANALOG output
CONVERTER

the late ’50s and early ’60s. I mention this to emphasize that a firm understanding of
fundamental principles is much more important to one’s long-term success in engi-
neering, or any field for that matter, than the learning of some specific skill. For
example, without a thorough understanding of Maxwell’s equations and Ohm’s law
and how they are applied, it would be difficult, if not impossible, to progress with
new technologies. My approach to troubleshooting circuits is, “The circuit will not
violate Ohm’s law.” If I make measurements that suggest the opposite, I look for
oscillations. But I digress-back to the “early years.”
The late 1950s were the times of vacuum tube digital computers with 16 K of
memory. Computing power that today fits on a desktop occupied hundreds of
square feet of space. The mechanical desktop calculators we used required several
seconds to multiply two 10-digit numbers. They were not portable, so everyone
carried slide rules that were quicker to use. easier to carry around, and didn’t need
110 V electrical power. The slide rule only produced an answer to three or four
significant digits. but this was not a real limitation since electrical engineering was
only a 1 % or at best a 0.1% science. Measuring instruments were all analog and
even a General Radio meter with the black crinkle finish and a mirrored scale (now
that shows my age) would only yield a voltage measurement of three significant
digits at best.
During the mid 1950s a 12-ounce container of Coke (which at that time referred
to a soft drink) cost a dime. The top-of-the-line Chevrolet and a year at a private
university cost about the sameS2,000. As an economist friend of mine once
pointed out, inflation is a relative thing, since the price of the Chevrolet ‘and a year’s
tuition for a private university have remained constant over the years.
The thirty or so years between the late 1950s and the present have brought many
changes. The vacuum tube digital computer which once occupied a room is now
fabricated on a silicon chip the size of your thumbnail. The mechanical calculator
and slide rule have disappeared and been replaced by the solar powered scientific
calculator. Electrical measurements are made with digital instruments that are accu-
rate to six or seven significant digits, and Coke is no longer just a soft drink. To
those of us in the analog world, digital technology is a two-edged sword. Digital
technology has created powerful tools for the analog designer to use, but it has also
depleted our ranks by attracting some of the most promising students. This is unfor-
tunate since some of the most challenging problems are analog in nature, and fewer
and fewer graduating engineers are equipped to solve them.
I classify analog designers into one of two categories. There are those who do
truly original work, and these I consider the artists of our profession. These individ-
uals, as in most fields, are very rare. Then there are the rest of us, who are indeed

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