Let's consider an op-amp:
From basic courses of electronics, we know that the output voltage as a function of the differential input is given by the following picture:
Now, assuming that:
- the op-amp is closed with negative feedback;
- the output voltage has a finite value;
- the open-loop gain is large enough (ideally infinite);
and Vin1 and Vin2 are almost equal (virtual short-circuit).
Question: when I turn on a given circuit containing an op-amp with negative feedback, the op-amp in general will not work exactly and immediately in the linear region of its characteristic. Does the op-amp go into the linear region thanks to the slew rate due to some parasitic capacitors (which are always present)?
This idea has come to my mind after reading the following example taken from Razavi's book:
Thanks to the load capacitor CL indeed we have that the output voltage either increases or decreases and, as a consequence, the difference between the two inputs of the differential pair returns small, thus restoring linearity.