Trying to understand how operational amplifiers work

[pairofstrings]

The way that opamps are usually used is in a linear mode.

This means that they have many levels of input signal that will produce many levels of output signal.

A digital circuit generally has two levels of input signal (possibly 5 volts and zero volts) and the output is one of two possible levels too.

There are exceptions to this and some opamp circuits can be digital in output. For example, the Schmitt trigger circuit or the opamp used as a comparator produce just two levels of output signal.

That means I can integrate this op-amp circuit in 'Digital Integrated Circuit' and also in 'Linear Integrated Circuit'.

 

[vk6kro]

It is probably best not to classify these things too much.

If you had to clasify opamps then they are mostly linear.

There are always exceptions. Some digital ICs can be used as linear amplifiers, too, but that is not their normal function.