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Opamp resistor magnitude

Try and find a copy of Tom Frederiksen's booklet, "Intuitive OpAmps". That should answer about any remaining questions you have. ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
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I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson
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Well, now that the sun manages to set on the British Empire, maybe 
He can take a Saturday off every now and then...
Reply to
John Fields

On Mon, 28 Apr 2014 00:44:23 -0400, Gone Postal trying to figure out is what determines the magnitude of the resistors

Low value resistors could load the opamp output, or in low-power applications use too much power. If they self-heat, or cause the opamp to heat, you can get weird thermal transients, usually only an issue in super-precision circuits.

If the resistors are too high, you can get...

more Johnson noise

more noise from opamp input noise current

Noise peaking from the pole (RC rolloff) that's created inside the feedback loop by the resistors and the opamp input capacitance

Ringing/oscillation, same reason

DC errors, from opamp input bias current or PCB leakage.

Current-mode opamps also care about the impedance seen at the inverting input; it directly affects the opamp gain-bandwidth.

--

John Larkin         Highland Technology, Inc 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

Thank you very much for the reference!

GP

Reply to
Gone Postal

Thank you for your assistance!

GP

P.S. Is it really necessary to go by my real name in this group? I prefer to try and keep Google blank when someone searches my real name, though s.e.b. isn't a bad group to be associated with I guess. I don't nym-shift without a really good reason, like the debacle in a.b.e.t. last year.

Reply to
Gone Postal

Actually, it still hasn't. Thank the Pitcairn Islands.

formatting link

Matt Roberds

Reply to
mroberds

Going by your real name is actually a big plus on Usenet, unless you have self-control issues. Some not-insignificant amount of my business comes from people looking at Usenet archives. Besides, as the old saying goes, "tell the truth and shame the devil."

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

Okay, here goes nothing!

And a thanks to everyone that has helped today.

Ray

Reply to
Ray Otwell

"Phil Hobbs"

** Hey dil,

got any idea what over answering is?

Or that YOU are feeding a very obvious troll ?

My god you are one dumb s*****ad.

... Phil

Reply to
Phil Allison

"Phil Hobbs"

** Hey dil,

got any idea what over answering is?

Or that YOU are feeding a very obvious troll ?

My god you are one dumb s*****ad.

... Phil

Reply to
Phil Allison

"Jim Thompson"

** Hey dil,

got any idea what over answering is?

Or that YOU are feeding a very obvious troll ?

My god you are one dumb s*****ad.

... Phil

Reply to
Phil Allison

"Gone Postal" "Phil Allison"

** FFS wot a wanker !!!!

Find similar examples on the net and link them.

You are such a damn obvious LIAR.

.... Phil

Reply to
Phil Allison

"John Fields"

** Hey dil,

got any idea what over answering is?

Or that YOU are feeding a very obvious troll ?

My god you are one dumb s*****ad.

... Phil

Reply to
Phil Allison

"John Fields"

** Hey dil,

got any idea what over answering is?

Or that YOU are feeding a very obvious troll ?

My god you are one dumb s*****ad.

... Phil

Reply to
Phil Allison

"Gone Postal"

** Piss OFF you damn TROLL !!!!

Reply to
Phil Allison

Welcome aboard, Ray!

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

Trolls need love too, Phil. ;)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

"Phil Hobbs"

** Huh ? Ray who, Ray what ????

And who made YOU king shit over everything ???

Even God despises smug, autistic bastards like you, Hobbs.

.... Phil

Reply to
Phil Allison

I guess you don't remember what welcoming people is like. Try it some time, it's fun.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

Phil (H.), Did you ever read any of the disc-world novels by Terry Pratchet? He's got that dry British wit similar to Doug Adams. (And nice characters.) I'm just polishing one off...(that has lovable Trolls in it.) You need to skip the early ones and start in the middle somewhere. And to keep this on topic... one novel was called "Going Postal".

George H.

Reply to
George Herold

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