Figure 1 : Circuit Diagram of CS-CS Amplifier

At mid frequency all connected capacitors acts as short circuit. Hence AC equivalent using JFET becomes,

Figure 2 : AC equivalent circuit

Av (Voltage Gain) :

Av2 = $\frac{Vo}{Vo1}$

Vo= Io Rd2 …..(1)

Io= $\frac{-gmVgs2×rd}{rd+Rd2}$ ……..(2) by CDR

Substitute equation (2) in …