Question

The asymptotic Bode plot shown below represents a lowpass filter-amplifier with a break frequency of .

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Design a circuit to be connected in cascade with the amplifier such that the break frequency is extended to .

Answer 1

Transfer function for given original Bode plot is G(s) = k/(1 + 10^-3 s)^2 at dc gain = 20 dB 20 log_10 G = 20 log_10 G = 1 G = 10 k = 10 G(s) = 10/(1 + s times 10^-3)^2 similarly final T/F function is G^�(s) = 10/(1 + s times 2 times 10^-4)^2 \r\n G^�(s) = G(s).H(s) H(s) = G^�(s)/G(s) = 10/(1 + s times 2 times 10^-4)^2/10/(1 + s times 10^-3)^2 = (1 + s times 10^-3/1 + s times 2 times 10^-4)^2 = (1 + s times 10^-3/1 + s times 2 times 10^-4) (1 + s times 10^-3/1 + s times 2 times 10^-4) Let T = 2 times 10^-4 a = b^-3/2 times 10^-4 = 5 > 1 (1 + a T_s/1 + T_s) (1 + a T_s/1 + T_s) \r\n CKt for head compensator is E_0 (s)/E_i (s) = R_2/R_1 + R_2 [1 + sc R_1/1 + s R_1 R_2 c/R_1