2.91 Use an ideal op amp to design a differentiator circuit having a time constant of 10−5 s using a 1-nF capacitor. Sketch the magnitude and phase response of the circuit, indicating the frequency at which the magnitude response equals 0 dB. A series input resistor is added to limit the gain magnitude at high frequencies to 100 V/V. Sketch the magnitude and phase responses of this modified circuit on the same axes as the ideal differentiator. How does the phase response change at high frequencies?