Groups > sci.electronics.design > #454204

Re: OpAmp Feedback Resistance vs. Stability

From	Hul Tytus <ht@panix.com>
Newsgroups	sci.electronics.design
Subject	Re: OpAmp Feedback Resistance vs. Stability
Date	2017-03-30 06:02 +0000
Organization	PANIX Public Access Internet and UNIX, NYC
Message-ID	<obi71r$341$1@reader1.panix.com> (permalink)
References	<w86dnc8WH8FDQkfFnZ2dnUU7-bvNnZ2d@giganews.com> <772ddd19-f896-480a-804c-b1fbd98d9c3e@googlegroups.com> <iY2dnYokLPQIekbFnZ2dnUU7-cednZ2d@giganews.com> <obhdul$4un$1@reader1.panix.com> <megodchqja0dadcg5l9errci2ed67d3kuk@4ax.com>

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Jim - I was familiar with the Motorola devices in the late 60's; those and 
RCA's but mostly the Fairchild opamp's, but that was mostly due to 
available purchasing channels.
   Fun times those. If one device was announced with break through 
features in the spring, there'd be a better one in the fall. 
Congratulations on a device that lasted 53 years. That's no mean 
accomplishment.   

Hul


Jim Thompson <To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:
> On Wed, 29 Mar 2017 22:54:13 +0000 (UTC), Hul Tytus <ht@panix.com>
> wrote:

> >Tim - the early opamps (lm707??) required "compensation" so that the loop 
> >gain was less than unity at the frequency where the phase shift was 180 
> >degrees. The first opamp that completely compensated itself, ie could be 
> >used at unity gain with no weird behavior, was, I think, the single 
> >version of the lm747. 
> >   Those versions that required compensation had special pins for
> >capacitors. But the circuitry between the output and the negative input 
> >could also be used for compensation, that is to reduce the loop gain with a 
> >low frequency rc filter. That is probably what you were doing with the 
> >rail to rail opamp. A 1K resister and 20 pf creates a 3 db point around 8 
> >mhz or so.
> >
> >Hul
> >

> [snip]

> My first OpAmp, MC1530/31, early '60's...

> <http://www.analog-innovations.com/SED/MC1530-DataSheet.pdf>

> was like that, external compensation, sliding-class-A output stage,
> still being sold by Lansdale (licensed from Motorola), 53-years later
> ;-)

> <http://www.analog-innovations.com/SED/MC1530-TeachingExercise.pdf>

> The military love it... absolutely stable, high-slew-rate for the era,
> indefinite-time short-circuit proof.
>                 
>                                         ...Jim Thompson
> -- 
> | James E.Thompson                                 |    mens     |
> | Analog Innovations                               |     et      |
> | Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
> | STV, Queen Creek, AZ 85142    Skype: skypeanalog |             |
> | Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
> | E-mail Icon at http://www.analog-innovations.com |    1962     |

>      Thinking outside the box... producing elegant solutions.

Thread

OpAmp Feedback Resistance vs. Stability Tim Wescott <seemywebsite@myfooter.really> - 2017-03-28 17:12 -0500
  Re: OpAmp Feedback Resistance vs. Stability Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-03-28 15:17 -0700
    Re: OpAmp Feedback Resistance vs. Stability Tim Wescott <seemywebsite@myfooter.really> - 2017-03-28 17:21 -0500
    Re: OpAmp Feedback Resistance vs. Stability Tim Wescott <tim@seemywebsite.com> - 2017-03-29 11:57 -0500
      Re: OpAmp Feedback Resistance vs. Stability Hul Tytus <ht@panix.com> - 2017-03-29 22:54 +0000
        Re: OpAmp Feedback Resistance vs. Stability Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-03-29 16:31 -0700
          Re: OpAmp Feedback Resistance vs. Stability George Herold <gherold@teachspin.com> - 2017-03-29 18:29 -0700
            Re: OpAmp Feedback Resistance vs. Stability George Herold <gherold@teachspin.com> - 2017-03-29 18:46 -0700
          Re: OpAmp Feedback Resistance vs. Stability Hul Tytus <ht@panix.com> - 2017-03-30 06:02 +0000
        Re: OpAmp Feedback Resistance vs. Stability Tim Wescott <tim@seemywebsite.com> - 2017-03-29 22:18 -0500
          Re: OpAmp Feedback Resistance vs. Stability tabbypurr@gmail.com - 2017-03-29 21:24 -0700
            Re: OpAmp Feedback Resistance vs. Stability Hul Tytus <ht@panix.com> - 2017-03-30 06:09 +0000
  Re: OpAmp Feedback Resistance vs. Stability Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-03-28 18:27 -0400
    Re: OpAmp Feedback Resistance vs. Stability bitrex <bitrex@de.lete.earthlink.net> - 2017-03-28 18:47 -0400
  Re: OpAmp Feedback Resistance vs. Stability John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-03-28 15:37 -0700
  Re: OpAmp Feedback Resistance vs. Stability George Herold <gherold@teachspin.com> - 2017-03-29 05:41 -0700

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