Electronics and Communication Engineering - Analog Electronics - Discussion

Why this formula?

fc/(1+B*Af).

It should be higher frequency formula, coupling reduce.

At i/p side for CE RC amplier there is a series feedback. I/p resistance must increases by (1+AB).

Yes @Shaz its absolutely right.

fl' = fl(1+A(beta)).

Approximately answer is 1050.

Besides having the formula F{new}= f{0}/ (1 + AB), there is another way around.

Remember that we have this Gain-Bandwidth Product. It means that the product of the gain and the bandwidth is always constant. In formula A * BW = constant. Or, BW = {constant}/{A}, where A is gain and BW is bandwidth. So as you can see, BW is inversely proportional to gain A.

If you have a negative feedback, the gain is always less than the open loop gain. It implies that the bandwidth will increase (inversely proportional remember) to compensate for the reduction of the gain.

Now notice from the choices that only letter C is less than 5 Hz. Since 5 Hz is the lower cutoff frequency, an increase in BW means a new frequency less than 5 Hz. Therefore, it is the only choice that indicates an increase in BW.

Thank you for giving the explanation.

Thank you all for the explanation.

Thank you all for the explanation.

Thanks to all.