7.16 In the cascaded MOSFET amplifier of Fig. 7-21, Ccoo. Find (a) the voltage-gain ratio Av₁/v, and (b) the current-gain ratio A₁ = i₁/i. VDD 218 R R11 R12 Rp га Cc R21 Fig. 7-21 R Rp2 Cc 8m2 R₂ SMALL-SIGNAL MIDFREQUENCY FET AND TRIODE AMPLIFIERS [CHAP. 7 (a) The small-signal equivalent circuit is given in Fig. 7-22. Using the result of Example 7.1, but replacing RD with RDi | RG2 where RG2 =R21 R22, we have Al -(RR) Fast + (RD|| RG2) (1) G₂ Rp Rot RG: 2 Fil RGI Fig. 7-22 -8m22(Rp2||RL) Similarly, Then (b) Realizing that RG₁ = R₁||R₁₂, we have Faz + (Roc R₂) Em&m2rds (RD|RG2)(RD||RL) +(RD|RG)2 + (Rp2||RL)] iL A₁ vo/RL v₁/RGI RG1 A RL where A, is given by (3). (2) (3)