- Design is the reverse of analysis: one starts with the Answer
(the Specification), and one has to work back to the beginning (circuit configuration
and element values). Therefore, only analysis that can be worked backwards is worth
doing. This is Design-Oriented Analysis.
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Design-Oriented Analysis is the process of
guiding and controlling the algebra so that the result is a
Low-Entropy Expression,
defined as one in which the terms are ordered, or
grouped, so that additional insight is obtained into
the relative importance of the various contributions
to the result. This is the source of the additional
information needed for design, and substitutes for the
missing equations that would be needed to solve
formally for the number of unknowns.
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The Design Feedback
Loop
Conventional design is an "open-loop" process:
An initial circuit diagram is analyzed, and the result compared
with the specification. If it doesn't match, an "open-loop" adjustment is made to the
circuit diagram, and the analysis is repeated in the hope that the result will come
out closer to the specification. When the analysis result is a High-Entropy
Expression, little guidance is provided on what elements to change in the circuit
diagram.
Design-Oriented Analysis
is a "closed-loop" process:
When the analysis result is a Low-Entropy Expression, any discrepancy between the
analysis result and the specification becomes an "error signal" which can be "fed
back" to suggest an adjustment to the circuit configuration or element values. The key
is that a Low-Entropy Expression can be "inverted", or "worked backwards", because the
ordering and grouping of terms discloses their contributions to the result. |
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