• Zi is overall i/p impedance.

$\therefore$ Zi = $R_1$ || $R_2$

• $Zi_2$ is i/p impedance of 2nd stage.

$\therefore$ $Zi_2$ = $R_3$ || $R_4$

• $Zo_1$ is o/p impedance of 1st stage.

$\therefore$ $Zo_1 = rd_1 || RD_1$

• Zo is overall o/p impedance.

Zo = $rd_2 || RD_2$

• $A_2$ is gain of 2nd stage.

|$A_2| = gm_2 (rd_2||RD_2$)

• $A_1$ is gain of 1st stage.

|$A_1| = gm_1 (rd_1 || RD_1 || Zi_2$)

• Let A is overall vol gain.

$\therefore$ A = | $A_1 | x | A_2$ |