Question

What type of filter is shown below in figure?

• A. High pass second order
• B. High pass first order
• C. Low pass second order
• D. Low pass first order

Answer 1

The correct option is C Low pass second order

The tansfer function is,
$H\left(s\right)=\frac{V_0\left(s\right)}{V_i\left(s\right)}=\frac{R||\frac{1}{sC}}{sL+R||\frac{1}{sC}}=\frac{R}{s^{2}RLC+sL+R}$
or $H\left(j\omega \right)=\frac{R}{-{\omega }^{2}RLC+j\omega L+R}$
Since $H\left(0\right)=1$ and $H\left(\infty \right)=0$
$\therefore$ The circuit is a second order low pass filter.