P1 ac case of an amplifier circuit including two amplifiers (A1 and A2) is shown in the picture, above. The ac models of A1 and A2 are given in the picture, below. Find the ac transconductance gain of the circuit (Gm-io/vk). (15P) b1 b2 A2 5k A1 a2 a1 2k 10k 5k Jl. 0.1k a1 10mS Vac1 b1 20xVac2 A2 ac model b2 A1 10k a2 5k 100k 2k ac model c1 c2