written 3.5 years ago by |
Step 1 :
Calculate $r_d$ -
$r_d=\dfrac{1}{Y_{os}}$
$\therefore r_d=\dfrac{1}{20 \times 10^{-6}}$
$\therefore r_d=50k \Omega$
Step 2 :
Calculate $g_m$
$\therefore g_m=\dfrac{I_D}{V_{DSQ}}$
But $I_D=\dfrac{V_{DD}-V_{DSQ}}{R_D}$
$\therefore I_D=\dfrac{10-2.75}{3.3}=2.197mA$
$\therefore g_m=\dfrac{2.197}{2.75}=0.7989mS$
Analysis with $r_d$
Step 1 :
Calculate $A_V$
$\therefore A_V=\dfrac{V_0}{V_i}=\dfrac{-g_mV_{gs}(r_d\mid\mid R_D \mid\mid R_F)}{V_gs}=-g_m(r_d\mid\mid R_D \mid\mid R_F)$
$\therefore A_V=-0.7989 \times 10^{-3}[50k \mid\mid3.3k\mid\mid10M]$
$\therefore A_V=-0.7989 \times 10^{-3}\times 3.095 \times 10^3=-2.473$
Step 2 :
Calculate $R_{MI} \ and \ Z_i $
$R_{MI}=\dfrac{R_F}{1-A_V}=\dfrac{10M}{1+2.473}=2.879M \Omega$
$Z_i=R_{MI}=2.879M \Omega$
Step 3 :
Calculate $Z_0$
$\therefore Z_0=r_d \mid\mid R_D \mid\mid R_{M2}$
$\therefore Z_0=50k \mid\mid3.3k \mid\mid 10M \Omega$
$\therefore Z_0=3.095k \Omega$
Analysis without $r_d$
Step 1 :
Calculate $A_V$
$A_V=-g_m(R_D \mid\mid R_{M2}) $
$\therefore A_V= -0.7989(3.3 \mid\mid10M \Omega)$
$\therefore A_V=-0.7989 \times 3.298=-2.6355$
Step 2 :
Calculate $Z_i$
$Z_i=R_{M1}=2.879M \Omega$
Step 3 :
Calculate $Z_0$
$\therefore Z_0=R_D \mid\mid R_{M2}$
$Z_0=3.3k \mid\mid10M \Omega$
$\therefore Z_0=3.298k \Omega$