The gain and bandwidth product of an ideal op amp is always constant. This statement seems to be true in the '-20dB slope' region. But this doesn't seem to be true for the low frequency region.
The two shaded regions below doesn't seem to represent the same gain bandwidth product.
I am not confused here with plot for gain at a particular bandwidth, which may seem as below and does not satisfy the gain bandwidth product (it should not) in the constant gain region.
What I think (I know I am wrong) why isn't the gain bandwidth product made something like this:
Can anyone please explain where am I wrong in my reasoning?
Best Answer
We're clearly not talking about ideal opamps here, which have infinite gain and infinite bandwidth, among other properties.
The G-BW product is a constant for any real opamp that has a dominant pole, and it only applies above the frequency associated with that pole.
Below that frequency, the opamp has some finite maximum gain dictated by the limitations of the devices used in its internal circuitry.