Small Signal Voltage Gain, Input and Output Resistance

Calculating the gain of this circuit is extremely simple. Generally, the total gain is the product of the gains of the individual stages. The only extra thing to remember is the load for the CE stage is the input resistance of the EF stage.

Determining the input resistance is simple. Since the input into the circuit looks identical to that of a simple one stage CE amp, R_in of the two stage amp is identical to that of the one stage CE amp of Part 1.4. Thus $R_{in}=r_{\pi}+\beta R_E$.

The output resistance is the same form as that of the EF amp of Part 1.5, with R_C1 playing the role of R_S and $R_B=\infty$.