Question

The y-parameters of a two-port network are
$\left[y\right]=\left[\begin{array}{cc}5& 3\\ 1& 2\end{array}\right]S$
A resistor of 1 $\Omega$ is connected across as shown in figure below. The new y parameter would be

• A. $\left[\begin{array}{cc}6& 4\\ 2& 3\end{array}\right]S$
• B. $\left[\begin{array}{cc}6& 2\\ 0& 3\end{array}\right]S$
• C. $\left[\begin{array}{cc}5& 4\\ 2& 2\end{array}\right]S$
• D. $\left[\begin{array}{cc}4& 4\\ 2& 1\end{array}\right]S$

Answer 1

The correct option is B $\left[\begin{array}{cc}6& 2\\ 0& 3\end{array}\right]S$

y-parameters of 1$\Omega$ resistor network are $\left[\begin{array}{cc}1& -1\\ -1& 1\end{array}\right]$
New y-parameter,
$=\left[\begin{array}{cc}5& 3\\ 1& 2\end{array}\right]+\left[\begin{array}{cc}1& -1\\ -1& 1\end{array}\right]$
$=\left[\begin{array}{cc}6& 2\\ 0& 3\end{array}\right]S$