For the amplifier in Problem 9.1, calculate and sketch plots of gain (in decibels) and phase versus frequency (log scale) with no feedback applied. Determine the value of f that just causes instability and the value of f giving a 60° phase margin.

Data from Prob. 9.1:

An amplifier has a low-frequency forward gain of 200 and its transfer function has three negative real poles with magnitudes 1 MHz, 2 MHz, and 4 MHz. Calculate and sketch the Nyquist diagram for this amplifier if it is placed in a negative feedback loop with f = 0.05. Is the amplifier stable? Explain.