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Problem 1: Consider the following system:

assignment-1-circuit
assignment-1-circuit

Let R1=40Ω,R2=20Ω,L=10mH,C=1μFR_1 = 40\Omega, R_2 = 20\Omega, L = 10mH, C= 1\mu F. The input is vinv_{in} the output is voutv_{out}. Give both transfer function and state space representation for the system.

Solution

Given circuit is a second-order linear system due to presence of one inductor (L) and one capacitor (C).

Given transfer function H(s)H(s) is given by the ratio over Laplace domain:

H(s)=Vout(s)Vin(s)H(s) = \frac{V_{out}(s)}{V_{in}(s)}

Given that the impedance of the inductor Zl=sLZ_l = sL and the impedance of the capacitor Zc=1sCZ_c = \frac{1}{sC}, the total impedance of the circuit is given by:

Ztotal=11sL+sCZ_{\text{total}} = \frac{1}{\frac{1}{sL} + sC}

Using voltage divider rule, the transfer function is given by:

H(s)=Vout(s)Vin(s)=1sC1sL+1sCH(s) = \frac{V_{out}(s)}{V_{in}(s)} = \frac{\frac{1}{sC}}{\frac{1}{sL} + \frac{1}{sC}}