9.54 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
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.
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