Numerical 6: Scaling

Perform scaling for R(new)=2000Ω, w=1rad/sec, C=10^5rad/sec

Perform scaling for R(new)=2000Ω, w=1rad/sec, C=105rad/secfig: unscaled LPF

\[
\textbf{Given:}
\]
\[
R_{\text{new}} = 2000\,\Omega,\quad \omega = 1\,\text{rad/sec},\quad C = 10^5\,\text{rad/sec}
\]

\[
\textbf{Scaling Factors:}
\]
\[
K_m = \frac{R_{\text{new}}}{R_{\text{old}}} = \frac{2000}{20} = 100
\]
\[
K_f = \frac{C}{\omega} = \frac{10^5}{1} = 10^5
\]

\[
\textbf{Resistor Transformation:}
\]
\[
\text{For } R_{\text{old}} = 1\,\Omega:\quad R_{\text{new}} = K_m \cdot R_{\text{old}} = 100 \cdot 1 = 100\,\Omega
\]

\[
\textbf{Inductor Transformation:}
\]
\[
L_{\text{new}} = L_{\text{old}} \cdot \frac{K_m}{K_f}
\]

\[
\text{For } L_{\text{old}} = 1\,H:\quad L_{\text{new}} = 1 \cdot \frac{100}{10^5} = 1\,\text{mH}
\]

\[
\text{For } L_{\text{old}} = 4\,H:\quad L_{\text{new}} = 4 \cdot \frac{100}{10^5} = 4\,\text{mH}
\]

\[
\textbf{Capacitor Transformation:}
\]
\[
C_{\text{new}} = C_{\text{old}} \cdot \frac{1}{K_m \cdot K_f}
\]

\[
\text{For } C_{\text{old}} = 0.5\,F:\quad C_{\text{new}} = 0.5 \cdot \frac{1}{100 \cdot 10^5} = 0.5\,\mu F
\]

The new circuit becomes

What is Scaling in Filter Design? Why is it necessary? Derive the expression to determine the new values of circuit element while applying both magnitude and frequency scaling?

fig: Scaled LPF

 

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