Derive an expression for the small-signal voltage gain vo/vi of the circuit shown in Fig. P9.54 in two different ways: (a) as a differential amplifier
(b) as a cascade of a common-collector stage Q1:
and a common-base stage Q2:
![855_kk.jpg](https://secure.tutorsglobe.com/CMSImages/855_kk.jpg)
Assume that the BJTs are matched and have a current gain α, and neglect the Early effect. Verify that both approaches lead to the same result