Consider an op amp having a single-pole, open-loop response with A0 =

Question

Notify Me Bookmark

Consider an op amp having a single-pole, open-loop response with A0 = 106 and fP = 10 Hz. Let the op amp be ideal otherwise (infinite input impedance, zero output impedance, etc.). (1) If the op amp wired as a unity-gain buffer, how large is β? (2) At what frequency the loop gain Aβ is equal to 1? What is the corresponding phase margin? (3) For the case of a manufacturing error introducing a second pole at 103 Hz. Sketch the bode plot of the open loop gain. What is now the frequency for which |Aβ| = 1? What is the corresponding phase margin? For what values of β is the phase margin 45∘ or more?

Image text

$[40 %]$ Consider an op amp having a single-pole, open-loop response with $A_{0} = 10^{6}$ and $f_{P}$ $= 10 H z$ . Let the op amp be ideal otherwise (infinite input impedance, zero output impedance, etc.). (1) If the op amp wired as a unity-gain buffer, how large is $β$ ? (2) At what frequency the loop gain $A β$ is equal to 1 ? What is the corresponding phase margin? (3) For the case of a manufacturing error introducing a second pole at $10^{3} H z$ . Sketch the bode plot of the open loop gain. What is now the frequency for which $| A β | = 1$ ? What is the corresponding phase margin? For what values of $β$ is the phase margin $45^{\circ}$ or more?