[HN Gopher] Linear Circuit Design Handbook (2008)
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Linear Circuit Design Handbook (2008)
Author : mindcrime
Score : 31 points
Date : 2021-07-16 19:17 UTC (3 hours ago)
(HTM) web link (www.analog.com)
(TXT) w3m dump (www.analog.com)
| JKCalhoun wrote:
| No one will ever be able to explain op-amps to me satisfactorily.
| I am too dense. But I am endlessly fascinated by them. Analog
| circuits have (re)kindled a love for electronics in me.
| jareklupinski wrote:
| The Art of Electronics introduced me to Transistor Man, who
| helpfully explained some of the more opaque topics with
| "there's a demon doin it" until the theory made more sense
| after learning more details
| https://electronics.stackexchange.com/a/476734
| analog31 wrote:
| My college didn't have an engineering department, but we took
| electronics as physics majors, using _The Art of Electronics._
| The rules that we learned in class work for a large number of
| op amp circuits:
|
| 1. The inputs draw no current
|
| 2. If there is negative feedback present, the output will do
| whatever is necessary to render the two inputs equal
|
| So you can write the equations for the voltages at the two
| inputs, include an equation that sets them equal, and solve for
| the output. To handle circuits like filters, you have to solve
| using complex numbers. This will be good enough to derive the
| design formulas in the handbooks.
|
| These days, a third good rule is:
|
| 3. Buy an op amp that works as well as needed to obey rules 1
| and 2 in your application. Op amps have made huge strides in
| terms of functionality and ease of design since I was in
| college 4 decades ago.
| GeorgeTirebiter wrote:
| This is one of the best explanations of op amps:
| https://www.ti.com/lit/an/sboa092b/sboa092b.pdf?ts=162646149...
| ms-fellag wrote:
| If watching videos is compatible with your learning style then
| i highly recommend this whole series on Youtube about Op-Amps,
| the channel is called RSD-Academy.
|
| This dude explained-it so well that i was astonished as to why
| i didn't 'get' before.
|
| [the first video you can skip to 1:45]
| <https://www.youtube.com/watch?v=7OuUiwI8fDk>
|
| [the whole series] <https://www.youtube.com/playlist?list=PLL_n
| f1OmixTTd7rEoqoM6...>
|
| There is also Dave Jones' op-amp tutorial at EEVBlog (if you
| like Aussie accents and a bit more detailed/technical
| explanation yet still targeted at beginners)
| <https://www.youtube.com/watch?v=7FYHt5XviKc>
| ur-whale wrote:
| Strange, op-amps (if you don't dive into pushing them to their
| limits, and if you steer clear of trying to understand how they
| are implemented) are actually a lot simpler to grok than - say
| - an NPN transistor.
| GeorgeTirebiter wrote:
| Well.... yes, and. If you think of an NPN transistor as a
| current-operated switch (e.g. to drive an LED or relay), then
| you can have a pretty simple model of said NPN transistor. If
| you want to make a low-noise PIN diode photodetector
| amplifier with an op amp, you want to understand noise per
| root Hz, input offset voltages, variations with temperature,
| gain, frequency and phase response, and so much more. So, as
| is often the case in Engineering: It Depends...
| ur-whale wrote:
| One thing I've never managed to wrap my head around is why many
| analog designers insist on calling op-amp based analog circuit
| design "linear design".
|
| If there's one thing these circuits are absolutely not it's being
| linear.
|
| Every interesting circuit using op-amps basically is interesting
| because of the various non-linear behaviors you have to deal with
| when you optimize the circuit.
| dreamcompiler wrote:
| Op-amps are (theoretically) just linear differential amplifiers
| with extremely high gain (like 10,000x or greater). They appear
| nonlinear in open-loop configuration because their gain is so
| high that any realistic input signal immediately pegs the
| output against the rails. But with negative feedback they start
| to appear linear again because you can set the gain to
| something more reasonable. They're marvelous devices.
| mhh__ wrote:
| The one thing I wouldn't expect from electrical engineers is a
| focus on nomenclature - I do love electronics but I am
| perpetually annoyed by similar niggles as you are (it seems) +
| a tendency to teach the same equation 3 times in 3 different
| regimes even though I have spent years training myself to be
| able to identify these approximations myself.
| tuatoru wrote:
| This is a somewhat contrarian statement--I'd like some
| explanation and examples of what you mean.
|
| I find a x10 amplifier with high Zin, low Zout, low noise, low
| error, and constant delay to be interesting enough.
|
| Every circuit is non-linear when used outside its design
| limits, but this hardly needs asserting.
|
| And of course real devices are not perfect. Resistors have
| inductance and capacitance and a thermal coefficient,
| capacitors likewise have flaws, wires have resistance and self-
| inductance, and circuit layout gives you stray capacitance,
| crosstalk, and instability. Op amps themselves produce noise,
| have input currents and offset voltages and limited slew rate
| and bandwidth. And so on, and on.
|
| But again, none of that needs asserting.
|
| While you certainly can design lot of deliberately non-linear
| circuits with op amps and non-linear devices in their feedback
| paths, it's difficult to design linear circuits without them,
| or instead with circuits, the core of which end up looking like
| simplified op-amps.
|
| So, what did you have in mind when you said "the various non-
| linear behaviours"?
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