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Issue #210 January 2008
Special Feature: 20th Anniversary Retrospective
That Was Then, This Is Now
by Ed Nisley
Start | Microcontrollers | Analog | Wetware | Contact Release | Sources & PDF
ANALOG
The classic LM741 op-amp in Photo 1 made its way into many designs, but today’s op-amps come much closer to the “ideal” circuits shown in textbooks. You can now ignore many of the second-order effects and still produce a functional circuit without any exotic components.
The ready availability of analog circuit simulation programs eliminates many design blunders before the first prototype. Running a Spice simulation no longer requires elaborate preparation; you can feed in a schematic, do some point-and-click setup, then (in a matter of seconds, not hours!) find out how the circuit works. Your first circuit board will probably behave just as you expected.
The laws of physics haven’t been repealed, alas, which means the complacency arising from those successes can produce truly baffling problems. Odd physical effects that don’t show up in the datasheets still affect today’s almost-ideal components, often in unexpected ways that never enter simple simulations.
Moore’s Law now lets you convert all that messy analog circuity into digital signal processing algorithms, with the assurance that mathematical computations don’t vary with temperature or suffer from crosstalk. DSP can produce much better results than any analog design, as long as you can handle the equations and verify the code. Ah, the joys of soft hardware!
However, messy analog circuitry still surrounds those DSPs and you must still understand how to make it work. Learn how the real world affects those nearly ideal components, then trade-off analog functions with digital algorithms, and you’ll go far in today’s Golden Age of analog design.
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