Question 19.10: Find [z] and [g] of a two-port network if [T] = [10 1.5 S 2 ...
Find [z] and [g] of a two-port network if
[ \pmb{T} ]=\left[\begin{array}{cc} 10 & 1.5 \Omega \\ 2 S & 4 \end{array}\right]
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If A = 10, B = 1.5, C = 2, D = 4, the determinant of the matrix is
∆_T = \pmb{AD − BC} = 40 − 3 = 37
From Table 19.1,
\pmb{z _{11}}=\pmb{\frac{ A }{ C }}=\frac{10}{2}=5, \quad \pmb{z _{12}}=\frac{\Delta_T}{ \pmb{C} }=\frac{37}{2}=18.5 \\ \space \\ \pmb{z _{21}}=\frac{1}{ \pmb{C} }=\frac{1}{2}=0.5, \quad \pmb{z _{22}}=\pmb{\frac{ D }{ C }}=\frac{4}{2}=2 \\ \space \\ \pmb{g _{11}}= \pmb{\frac{ C }{ A }}=\frac{2}{10}=0.2, \quad \pmb{g _{12}}=-\frac{\Delta_T}{ \pmb{A} }=-\frac{37}{10}=-3.7 \\ \space \\\pmb{g _{21}}=\frac{1}{ \pmb{A} }=\frac{1}{10}=0.1, \quad \pmb{g _{22}}=\pmb{\frac{ B }{ A }}=\frac{1.5}{10}=0.15
TABLE 19.1
Conversion of two-port parameters.
z | y | h | g | T | t | |||||||
z | \pmb{z}_{11} | \pmb{z}_{12} | \frac{\pmb{ y} _{22}}{\Delta_y} | – \frac{\pmb{ y} _{12}}{\Delta_y} | \frac{\Delta_h}{ \pmb{h} _{22}} | \frac{\pmb{h}_{12}}{\pmb{h} _{22}} | \frac{1}{ \pmb{g} _{11}} | -\frac{\pmb{g}_{12}}{\pmb{g} _{11}} | \pmb{\frac{A}{C}} | \frac{\Delta_T}{\pmb{C}} | \pmb{\frac{d}{c}} | \frac{1}{\pmb{c}} |
\pmb{z}_{21} | \pmb{z}_{22} | – \frac{\pmb{ y} _{21}}{\Delta_y} | \frac{\pmb{ y} _{11}}{\Delta_y} | – \frac{\pmb{h}_{21}}{\pmb{h} _{22}} | \frac{1}{ \pmb{h} _{22}} | \frac{\pmb{g}_{21}}{\pmb{g} _{11}} | \frac{\Delta_g}{ \pmb{g _{11}}} | \frac{1}{\pmb{C}} | \pmb{\frac{D}{C}} | \frac{\Delta_t}{\pmb{c}} | \pmb{\frac{a}{c}} | |
y | \frac{ \pmb{z} _{22}}{\Delta_z} | -\frac{ \pmb{z} _{12}}{\Delta_z} | \pmb{y}_{11} | \pmb{y}_{12} | \frac{1}{ \pmb{h} _{11}} | -\frac{ \pmb{h} _{12}}{ \pmb{h} _{11}} | \frac{\Delta_g}{ \pmb{g} _{22}} | \frac{ \pmb{g} _{12}}{ \pmb{g} _{22}} | \pmb{\frac{\text { D }}{\text { B }}} | -\frac{\Delta_T}{\pmb{ B} } | \pmb{\frac{ a }{ b }} | -\frac{1}{ \pmb{b} } |
-\frac{ \pmb{z} _{21}}{\Delta_z} | \frac{ \pmb{z} _{11}}{\Delta_z} | \pmb{y}_{21} | \pmb{y}_{22} | \frac{\pmb{ h} _{21}}{ \pmb{h} _{11}} | \frac{\Delta_h}{\pmb{ h} _{11}} | -\frac{ \pmb{g} _{21}}{\pmb{ g} _{22}} | \frac{1}{ \pmb{g} _{22}} | -\frac{1}{ \pmb{B }} | \pmb{\frac{ A }{ B }} | -\frac{\Delta_t}{\pmb{ b} } | \pmb{\frac{ d }{ b }} | |
h | \frac{\Delta_z}{ \pmb{z} _{22}} | \frac{ \pmb{z} _{12}}{\pmb{ z} _{22}} | \frac{1}{ \pmb{y} _{11}} | -\frac{ \pmb{y} _{12}}{ \pmb{y} _{11}} | \pmb{h}_{11} | \pmb{h}_{12} | \frac{ \pmb{g} _{22}}{\Delta_g} | -\frac{ \pmb{g} _{12}}{\Delta_g} | \pmb{\frac{B}{D}} | \frac{\Delta_T}{ \pmb{D} } | \pmb{\frac{b}{a}} | \frac{1}{\pmb{a}} |
-\frac{ \pmb{z} _{21}}{ \pmb{z}_{22}} | \frac{1}{ \pmb{z} _{22}} | \frac{ \pmb{y} _{21}}{ \pmb{y} _{11}} | \frac{\Delta_y}{\pmb{ y} _{11}} | \pmb{h}_{21} | \pmb{h}_{22} | -\frac{ \pmb{g} _{21}}{\Delta_g} | \frac{ \pmb{g} _{11}}{\Delta_g} | -\frac{1}{\pmb{D}} | \pmb{\frac{C}{D}} | \frac{\Delta_t}{ \pmb{a} } | \pmb{\frac{c}{a}} | |
g | \frac{1}{ \pmb{z} _{11}} | -\frac{ \pmb{z} _{12}}{ \pmb{z} _{11}} | \frac{\Delta_y}{ \pmb{y} _{22}} | \frac{ \pmb{y} _{12}}{ \pmb{y} _{22}} | \frac{ \pmb{h}_{22}}{\Delta_h} | -\frac{ \pmb{h} _{12}}{\Delta_h} | \pmb{g}_{11} | \pmb{g}_{12} | \pmb{\frac{ C }{ A }} | -\frac{\Delta_T}{ \pmb{A} } | \pmb{\frac{ c }{d }} | -\frac{1 }{ \pmb{d}} |
\frac{ \pmb{z} _{21}}{ \pmb{z} _{11}} | \frac{\Delta_z}{ \pmb{z} _{11}} | -\frac{\pmb{ y} _{21}}{ \pmb{y} _{22}} | \frac{ 1}{ \pmb{y} _{22}} | -\frac{ \pmb{h}_{21}}{\Delta_h} | \frac{ \pmb{h} _{11}}{\Delta_h} | \pmb{g}_{21} | \pmb{g}_{22} | \frac{ 1 }{ \pmb{A} } | \pmb{\frac{ B }{ A }} | \frac{\Delta_t}{ \pmb{d} } | -\pmb{\frac{ b }{ d}} | |
T | \frac{\pmb{ z} _{11}}{\pmb{ z} _{21}} | \frac{\Delta_z}{ \pmb{z} _{21}} | -\frac{ \pmb{y} _{22}}{ \pmb{y} _{21}} | -\frac{1}{ \pmb{y} _{21}} | -\frac{\Delta_h}{ \pmb{h} _{21}} | -\frac{ \pmb{h} _{11}}{ \pmb{h} _{21}} | \frac{1}{ \pmb{g} _{21}} | \frac{ \pmb{g} _{22}}{ \pmb{g} _{21}} | A | B | \frac{\pmb{ d} }{\Delta_t} | \frac{\pmb{ b} }{\Delta_t} |
\frac{1}{\pmb{ z} _{21}} | \frac{\pmb{ z} _{22}}{\pmb{ z} _{21}} | -\frac{\Delta_y}{ \pmb{y} _{21}} | -\frac{ \pmb{y} _{11}}{ \pmb{y} _{21}} | -\frac{ \pmb{h} _{22}}{ \pmb{h} _{21}} | -\frac{1}{ \pmb{h} _{21}} | \frac{ \pmb{g} _{11}}{ \pmb{g} _{21}} | \frac{\Delta_g}{ \pmb{g} _{21}} | C | D | \frac{\pmb{ c} }{\Delta_t} | \frac{\pmb{ a} }{\Delta_t} | |
t | \frac{\pmb{ z} _{22}}{\pmb{ z} _{12}} | \frac{\Delta_z}{ \pmb{z} _{12}} | -\frac{ \pmb{y} _{11}}{ \pmb{y} _{12}} | -\frac{1}{ \pmb{y} _{12}} | \frac{1}{ \pmb{h} _{12}} | \frac{ \pmb{h} _{11}}{ \pmb{h} _{12}} | – \frac{\Delta_g}{ \pmb{g} _{12}} | -\frac{ \pmb{g} _{22}}{ \pmb{g} _{12}} | \frac{\pmb{ D} }{\Delta_T} | \frac{\pmb{ B} }{\Delta_T} | a | b |
\frac{1}{\pmb{ z} _{12}} | \frac{\pmb{ z} _{11}}{\pmb{ z} _{12}} | -\frac{\Delta_y}{ \pmb{y} _{12}} | -\frac{ \pmb{y} _{22}}{ \pmb{y} _{12}} | \frac{ \pmb{h} _{22}}{ \pmb{h} _{12}} | \frac{\Delta_h}{ \pmb{h} _{12}} | -\frac{ \pmb{g} _{11}}{ \pmb{g} _{12}} | -\frac{1}{ \pmb{g} _{12}} | \frac{\pmb{ C} }{\Delta_T} | \frac{\pmb{ A} }{\Delta_T} | c | d |
Thus,
[ \pmb{z} ]=\left[\begin{array}{cc}5 & 18.5 \\ 0.5 & 2 \end{array}\right] \Omega, \quad[ \pmb{g} ]=\left[\begin{array}{cc} 0.2 S & -3.7 \\ 0.1 & 0.15 \Omega \end{array}\right]