The given uncompensated system \(\frac{{900}}{{s\left( {s + 1} \right)\left( {s + 9} \right)}}\) is to be such that its gain crossover frequency becomes same as its uncompensated phase crossover frequency and provides a 45° phase margin. To achieve this, one may use
1
a lag compensator that provides an attenuation of 20 dB and a phase lag of 45° at the frequency of 3√3 rad/s
2
a lead compensator that provides an amplification of 20 dB and a phase lead of 45° at the frequency of 3 rad/s
3
a lag-lead compensator that provides an amplification of 20 dB and a phase lag of 45° at the frequency of √3 rad/s
4
a lag-lead compensator that provides an attenuation of 20 dB and phase lead of 45° at the frequency of 3 rad/s