Page 37 - Analog Circuit Design Art, Science, and Personalities

Is Analog Circuit Design Dead?

Figure 4-1.
Some analog
tvP ies are merely
leaving town.

As digital systems came on line in the late 1950s and early 1960s, a protracted
and brutally partisan dispute (some recall it as more of a war) arose between the
analog and digital camps. Digital methods offered high precision at the cost of
circuit complexity. The analog way achieved sophisticated results at lower accuracy
and with comparatively simple circuit configurations. One good op amp (eight
transistors) could do the work of 100 digitally configured 2N404s. It seemed that
digital circuitry was an accurate but inelegant and overcomplex albatross. Digital
types insisted that analog techniques could never achieve any significant accuracy,
regardless of how adept they were at modeling and simulating real systems.
This battle was not without its editorializing. One eloquent speaker was George A.
Philbrick, a decided analog man, who wrote in 1963 (in The Lightning Empiricist,
Volume 11, No. 4, October, “Analogs Yesterday, Today, and Tomorrow,” pp. 3-43),
“In modest applications to on-line measurement and data processing, it is quite
generally conceded that the advantage of continuous analog apparatus make it irre-
sistible. This is partly owing to the simplicity and speed which its continuity makes
possible, and partly to the fact that almost every input transducer is also ‘analog’ in
character, that is to say, continuous in excursion and time.”
Philbrick, however, a brilliant man, was aware enough to see that digital had at
least some place in the lab: “Only the most hard-shelled of analog champions would
suggest that all simulative and computational equipment be undiluted by numerical
or logical adjuncts.”
He continued by noting that “some analog men, perhaps overfond and defensive
as regards continuous functions, really believe that analog operations are general-
izations of digital ones, or that conversely digital operations are special cases of
analog ones. What can be done with such people?
“While it is agreed that analog and digital techniques will increasingly cross-
fertilize and interrelate,” Philbrick concluded, “it is predicted that the controversy
between their camps will rage on, good natured but unabated, for years to come in
spite of hybrid attachments.”
Although Philbrick and others were intelligent enough to prevent their analog
passions from obscuring their reasoning powers, they could not possibly see what
was coming in a very few years.

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