An emitter-follower amplifier is shown in the figure, $Z_{i}$ is the impedance looking into the base of the transistor and $Z_{0}$ is the impedance looking into the emitter of the transistor.
- Draw the small signal equivalent circuit of the amplifier.
- Obtain an expression for $Z_{i}.$
- Obtain an expression for $Z_{0}$.
- Determine $Z_{i}$ and $Z_{0}$ if a capacitor $C_{L}$ is connected across $R_{L}$.