EE 321 Lab
Prelab for Lab 1: Amplifiers, Biasing, and AC Coupling

This prelab is should be completed before coming to lab. Doing the prelab before coming to lab will get you out on time. Waiting until your lab session WILL KEEP YOU IN THE LAB WELL PAST DINNER.

1) Explain the difference between the three representations of the amplifier (shown in figures 1, 2, and 3). What is the purpose of each?

2) From your knowledge of op amps, try to determine Ri, Ro and Avo from inspection of Figure 3. If you have not yet learned all of this, skip those parts.

3) Why is the input resistance measured in the manner described in part 2?

4) Why is the best size of a test resistor one close to Ri? To help answer this question, find the error in Ri caused by a 0.01 V measurement error in both the input voltage and voltage across the test resistor. Do this for these 3 cases: RT=100 Ri, RT=10 Ri, and RT=Ri. Assume the source voltage is 2 V.

5) Why can't you use an ohm meter to find Ri?

6) Why is the output resistance measured in the manner described in part 3?

7) In part 5 find the value of R1 if Ri were 1 K (it's not) and the gain was 10.