loose-electron wrote on Dec 1st, 2011, 2:13pm:Completely different? Yes and No.
Use of ideal models are a simplified method to gain a better understanding of something.
We all use those all the time.
Also, an ideal op-amp can be dropped into the middle of something, and then add gain limitations, and explicit phase-gain properties outside the ideal amplifier.
That lumped model allows investigation into the separate parameters of the model.
i.e. adjust gain, phase characteristics without a need to redesign an entire device down at the transistor level.
Depends on what you are trying to achieve? Understanding the characteristics of something or building a circuit to plug in and turn on?
Hi Loose-electron.
In principle, I agree with all of the above.
But I think my description of a specific case (my first posting opening this thread) can serve as an example that your explantions/justifications of idealized models do not always apply.
As I have reported, there are circuits that show a behaviour that is strongly dependent on the amplifier model used for simulation (ideal or real). It is obvious that this cannot lead to a "better understanding" of the circuit and it's function.
On the other hand, if one is able to understand the
reason for the observed phenomena, this certainly will enlarge the knowledge of system theory and related areas.
Perhaps it's useful to give you a very simple
example:
Try to simulate an IDEAL opamp with
positive resistive feedback (10k/1k).
Of course, such a circuit will not work as an amplifier. However, all simulations (OP, AC, DC, TRAN) will result in a stable inverting amplifier with a gain of 20 dB. Does this lead to a better understanding of amplifiers?
And it is a fact, that the simulator did not make any error at all. The result is correct!