Figure P8.47 shows a composite pnp Darlington emitter follower that sinks current from a load. Parameter (I_{Q})

Question:

Figure P8.47 shows a composite pnp Darlington emitter follower that sinks current from a load. Parameter $I_{Q}$ is the equivalent bias current and $Z$ is the equivalent impedance in the base of $Q_{1}$. Assume the transistor parameters are: $\beta(\mathrm{pnp})=10, \beta(\mathrm{npn})=50, V_{A P}=50 \mathrm{~V}$, and $V_{A N}=100 \mathrm{~V}$, where $V_{A P}$ and $V_{A N}$ are the Early voltages of the pnp and npn devices, respectively. Calculate the output resistance $R_{o}$.

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