Author Topic: Op-amp: "Under the hood"  (Read 2224 times)

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Offline sasaTopic starter

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Op-amp: "Under the hood"
« on: October 01, 2017, 12:30:59 pm »
Dave,

In the episode #600 (I watched long time ago), you have explaining op-amp functionality. This is one of the best explanation I have ever seen, in exception of two small things: some math incorrectness (missing brackets, IIRC) and missing explanation how to properly handle unused op-amps in multiple op-amps IC...

In any event, to paraphrase your few words from episode #600: "You do not want the hard way to understand op-amps, you want the easy way!"...

Not enough in my case though, perhaps other people as well. I always find better to look "under the hood" for better understanding why it actually do what it do than only what. I simply find that much efficient educational model in order to understand and  remember elementary stuff, which later also help to understand exactly all variations of it and reasons of their existence.

You did excellent such "under the hood" review for NE555 and such similar review may as well be interesting for one of the simplest op-amp as is LM741.

Just a small suggestion to eventually consider for any of future videos, for these who prefer video explanation. Otherwise, this post with all documentation links is more than helpful:

https://www.eevblog.com/forum/beginners/opamps-for-everyone-pdf/
« Last Edit: October 01, 2017, 01:50:06 pm by sasa »
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Offline David Hess

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Re: Op-amp: "Under the hood"
« Reply #1 on: October 01, 2017, 07:16:09 pm »
The 741 is actually pretty complicated because of its cascode input stage which is used to support a high differential input voltage.  The 4136 or 324 is easier to understand.  The 324 has the virtue in that you can find both simplified and complete schematics to compare them although Texas Instruments of course lies, err, I mean labels theirs incorrectly.

The Audio Power Amplifier Design Handbook by Douglas Self goes into detail about 3 stage operational amplifier design and can be applied directly to the 741, 4136, and 324.

The old National application note A, The Monolithic Operational Amplifier: A Tutorial Study, is an excellent reference which covers exactly what you are asking for.
 

Offline rfeecs

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Re: Op-amp: "Under the hood"
« Reply #2 on: October 02, 2017, 06:44:44 pm »
I found this really interesting:
"IC Op-Amps Through the Ages":
http://www.ee.bgu.ac.il/~angcirc/History/Solutions_2003_2004_B/SomeStuff/History18opamp.pdf

It goes through the design of many of the early op-amps and shows the progression of improvements with each new design.
 

Offline David Hess

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Re: Op-amp: "Under the hood"
« Reply #3 on: October 02, 2017, 09:43:46 pm »
I found this really interesting:
"IC Op-Amps Through the Ages":
http://www.ee.bgu.ac.il/~angcirc/History/Solutions_2003_2004_B/SomeStuff/History18opamp.pdf

It goes through the design of many of the early op-amps and shows the progression of improvements with each new design.

Section 8-4 of Op Amp Applications Handbook by Walter Jung is very similar.  The whole thing is available on Analog Device's website:

http://www.analog.com/en/education/education-library/op-amp-applications-handbook.html
 


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