Experiment: Effect of Input and Output Resistances

1.

Construct the circuit in Fig. 2.10. Notice that it is really just the CE amp of Fig. 2.6, driving a load of R_L=1K, and being driven by a voltage source with source resistance R_S=10k.

2.

Using the expressions above, theoretically determine the voltage gain of the circuit.

3.

Measure the voltage gain $\frac{v_{out}}{v_s}$under the same input voltage and frequency conditions as in Exp. 2.4.2. Compare the measured gain with your theoretical result.

4.

Try two different values for the load resistor: let R_L=5K and R_L=10K. From the output voltages measured for the different values of R_L determine the output resistance of the CE amp R_out. Compare the value with the theoretical one.

5.

Replace R_L with its original value of 1K. Now, measure the AC voltage at the base. Now repeat your measurement with two different values for the source resistor: let R_S=5K and R_S=10K. From the base voltages measured for the different values of R_S determine the input resistance of the CE amp R_in. Compare the value with the theoretical one.