Hi

Can someone help me on the following question:
View attachment question8_BiCMOS.pdf
for part c in this question i don't understand why my answer does not match.
Av=-gm1RL*[(R1||rpi2)gm1]/[(R1||rpi2)gm2+1]

Av=0.5014RL*[74.198]/[75.198]

Av=37.202877RL/75.198

P.S

 

The equation for the voltage gain show in book is a correct answer.
I get the same answer after solving this

(0 - Vout)/RL = gm1 * (Vout - Vin) + ( gm2 * ( gm1 * (Vout - Vin) * R1))