Using opamp with GBP of 500kHz - 1Mhz for amplifying 20mV p-p signal to 5V p-p

[Old Nick]

Re: Opamp GBP

It can 'process' signals of 10 MHz.

It is slew limited to 10's MHz across the rails.

so this opamp is slew limited to 10mhz but how did it get rated 10ghz?

It is quite clear your understanding of this is a bit limited.

sure, that's why I am here to learn from you.

Also your aggressive attitude is rather unbecoming.

no reason to take it personal. if you know your stuff, lay it out and others will be convinced.

who 'rated' it 10 GHz? That is it;'s small signal bandwidth.

I'm not taking anything personal(ly), but you are being rude and dismissive to people more qualified than yourself to talk on this matter. I and others have layed it out, as you say, and you have argued/back pedalled/etc. with snide comments.

 

[millwood]

Re: Opamp GBP

who 'rated' it 10 GHz? That is it;'s small signal bandwidth.

so how did it get a small signal bandwidth of 10ghz?

I'm not taking anything personal(ly), but you are being rude and dismissive to people more qualified than yourself to talk on this matter. I and others have layed it out, as you say, and you have argued/back pedalled/etc. with snide comments.

I am the old one here talking about the facts. I am not the one telling the other party that they don't understand what they are talking about, and their understanding is limited, or they have an attitude problem, or to brag about my supposedly "experience", etc.

I simply wanted to know the factual basis of your comments so we can tell if you are for real or not.

if you don't want to answer my questions, that's fine with me. but it doesn't pay for you to put down others.

BTW, my background is in EE and I worked long year in the electronics business and in a semifoundry with SiGe processes for high speed (rf power amp) applications. But none of that have anything to do with the merits, or lack of, of my comments here or anywhere else.

 

[Audioguru]

Opamp GBP

Isn't the rude, dismissive, aggressive newbie the same newbie who was recently banned from another electronics chat forum for being a rude, dismissive and aggressive newbie??

 

[millwood]

Re: Opamp GBP

Isn't the rude, dismissive, aggressive newbie the same newbie who was recently banned from another electronics chat forum for being a rude, dismissive and aggressive newbie??

again, I am happy to talk to you or anyone about any technical issues, about facts.

if you are interested in talking about anything else, you are on your own.

my questions continue:

1) how do you know that you have a 10ghz bandwidth amp that cannot "slew 10mhz to the rails", whatever that means?
2) how do you have a large signal property when the property is defined as dv/dt?

 

[LvW]

Re: Opamp GBP

Quote MILLWOOD:
dv/dt is by definition an infinitesimal (read: infinitely small) change of voltage over an infinitesimal change in time.
if that doesn't constitute a "small" signal definition, what else does? Smile
what you described is delta v / delta t: a finite change in voltage over a finite period of time.
this is just basic calculus. so if you agree that SR=dv/dt is correct (which you did), you have to disagree with yourself about whether SR is a small signal or a large signal definition.

Hi, I don´t want to jump into the discussion again.
However, two recommendations to MILLWOOD:

Try to understand the technical background and the physical REASON for the slew rate effect: A capacitor is charged by a transistor of the first opamp stage which works as a CURRENT source. Why current source ? Because the stage is overdriven and works under LARGE SIGNAL conditions.

And secondly, have a look into a good book for opamp basics and read about the definition of GROUP DELAY - and learn that it has absolutely nothing to do with slew rate properties. Group delay is derived from the small signal ac phase response (sinus excitation).

Good luck.

Added after 2 hours 59 minutes:

Remark: By saying above, that the 1st opamp stage works as a "current source" I mean of course "constant current source". That´s important !

 

[millwood]

Re: Opamp GBP

Try to understand the technical background and the physical REASON for the slew rate effect: A capacitor is charged by a transistor of the first opamp stage which works as a CURRENT source. Why current source ? Because the stage is overdriven and works under LARGE SIGNAL conditions.

Cdom is always charged and discharged by the idle current in the VAS, not the input stage. that is true for small signal and large signal properties and has nothing to do with if the input or the VAS is overdriven - an VAS overdriven becomes another issue for another day.

the above is true mostly for VFB opamps. CFB opamps have a totally different input and VAS stage that render this discussion moot.

And secondly, have a look into a good book for opamp basics and read about the definition of GROUP DELAY - and learn that it has absolutely nothing to do with slew rate properties. Group delay is derived from the small signal ac phase response (sinus excitation).

if you read what I wrote, it wasn't saying group delay is causing low SR. what I WAS saying is that what you described is group delay.

and that can happen with any form of signal.

Remark: By saying above, that the 1st opamp stage works as a "current source" I mean of course "constant current source". That´s important !

the input stage doesn't have to have a constant current source - a lowly resistor will work just fine. but they typically do have some form of active loading. current mirrors for example are widely used.

 

[LvW]

Re: Opamp GBP

As I have said: Good luck and big success wherever you are going to work.

 

[millwood]

Re: Opamp GBP

As I have said: Good luck and big success wherever you are going to work.

thank you. i am done working, fortunately.

 

[LvW]

Re: Opamp GBP

Fine !

Perhaps you have time to have a short look into Par. 4 of the enclosed paper.
Regards

 

[millwood]

Re: Opamp GBP

Fine !

Perhaps you have time to have a short look into Par. 4 of the enclosed paper.
Regards

that's a fine read.

BTW, why do you post something that disputes your own arguments?

 

[LvW]

Re: Opamp GBP

Fine !

Perhaps you have time to have a short look into Par. 4 of the enclosed paper.
Regards

that's a fine read.
BTW, why do you post something that disputes your own arguments?

Perhaps because I am fair ? No, that´s a joke. But tell me which parts are against my arguments ?

 

[millwood]

Re: Opamp GBP

But tell me which parts are against my arguments ?

lvw, that would be the least of your problems, .

good luck in your day job.