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Simple Error Amplifier
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Kleinstein:
Usually the compensation circuit is more important than the OP. If the OP is fast enough it is the external circuit that sets the speed and not the OP anymore. The shown circuit is a little unusual in this respect.

Usually an OP with something like 1-3 MHz GBW is considered fast enough. In some circuits even the slow OP07 or LM358 might be fast enough.  The feedback divider also has an influence on how fast the OP needs to be. Quite some circuit have more feedback for the AC part and this way can operate with an OP that is slower.

The more important parameters for the choice of OP can be noise, DC drift and in some high impedance circuits also input bias. For a simple lab supply something like an TL07x / LF411 / RC4558 can be good enough. If one wants a really fast regulating supply it needs fast output transistors and care with the parasitic properties - using as faster OP alone does not help. Looking at parasitic inductance in the 10's of nH range is what makes this difficult. Another point to consider is that transistors / MOSFETs get slower at low current and thus 2 quadrant operation might be a good idea if a high speed is needed.
Benta:
The compensation of the opamp has values that are so large, that you can be certain that it is compensating the whole loop, not just the opamp.

Hint for readable schematics: always draw siganls as signals. Do not rely on implication through a couple of ground symbols.

diyaudio:
Some op-amps configured with high gain will function pretty fine as a comparator (in slow applications), selection will depend on a few factors not limited to.
 
* Speed
* Slew Rate
* High noise as a result of gain feedback path at the summing points.
* Cost

Lee Leduc:
Here's an Analog Devices app note AN-849 discussing the pros and cons of using opamps as comparators.
Efe_114:
Sorry for replying to this old topic but i wanted to clear the fog about E3610a schematics
full schematic at the attachment.
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