Op Amp Stability

[LvW]

Hey Lvw
I thought I would use the most common configuration of buffer seen in most text books and that is single supply operation and I figured most people would use this to buffer voltage higher than the common mode limit? Is this what you mean. Would you like me to mention about the limitations of this configuration. Or add a split supply version.
Cheers
Adam

I have seen a lot of textbooks on opamps - but I didn`t get the feeling that a single supply buffer configuration can be "seen in most text books".
In many cases, no supply rails are shown at all (because split supply is assumed without mentioning).
In many cases, for single supply operation a separate chapter is reserved (showing some methods for artificial biasing).
No - I don´t worry about common mode properties, but the limitation is clear: No negative voltages and - in particular - no pure ac signals are allowed., unless an artificial operating point somewhere in the middle between 0 and Vcc is created. In this case, ac signals can be used as well.

 

[Arouse1973]

Yes valid point Lvw. I am just used to working with d.c where this configuration is how it is mostly done, for as you say non a.c signals. I'll make a mention to this in the thread or change to split supply and then add some additional stuff on single supply operation to include this buffer circuit.
Thanks
Adam

 

[Albertisthebest]

I note you said you'd welcome feedback.

1. This does look like the start of something we could put into the tutorial section
2. It might be nice to add some figure numbers to your images for easier reference (I might do that just to make it easier for me to give you feedback. (done, I hope you don't mind)
3. You may not be able to edit your post after some time, that may pose some difficulties, but maybe we can figure something out...
4. In figure 3 it seems pretty clear which is the signal gain and which is the phase,air column bag but it may not be so clear for beginners. Perhaps you can add some words to describe this the first time. Also it might be useful to discuss why the phase isn't 180 degrees at the minimum frequency (as you might expect). I note you may have meant 800kHz (not 800Hz in the next paragraph)
5. In the first paragraph of the "Single pole response" section, it would be great to have the points you're talking about marked on the graph.
6. Jut under figure 4 you say "this is what happens when I add 100nF". It is not clear what "this" is, nor where you have added 100nF. Perhaps an updated diagram is needed?

I'll certainly have more feedback, but I'll stop there in case it is my understanding that is faulty (especially about the last point).