Opamp resistor magnitude

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.

Thank you very much for the reference!

GP

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.

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

Matt Roberds

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

Okay, here goes nothing!

And a thanks to everyone that has helped today.

Ray

"Phil Hobbs"

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

"Phil Hobbs"

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

"Jim Thompson"

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

"Gone Postal" "Phil Allison"

Find similar examples on the net and link them.

You are such a damn obvious LIAR.

.... Phil

"John Fields"

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

"John Fields"

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

"Gone Postal"

Welcome aboard, Ray!

Cheers

Phil Hobbs

Trolls need love too, Phil. ;)

Cheers

Phil Hobbs

"Phil Hobbs"

And who made YOU king s*it over everything ???

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

.... Phil

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

Cheers

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.