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

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.

The purpose of this lab is to measure the characteristics of an amplifier, and to use the characteristics to add a bias circuit at the input. We will represent the same amplifier three different ways. These are a block diagram, a model, and a schematic of the components. Figure 1 shows the block diagram of a generic amplifier. Figure 2 shows the model for a voltage amplifier. The characteristics which we need to measure are Ri, Ro and Avo.


We will use the circuit in Figure 3 as our amplifier. (Use a 741 or similar op-amp; the 741 pin out is shown in Figure 4.) In Figures 1, 2 and 3, the input to our amplifier is at A and the output at B. If we can find the three values Ri, Ro, and Avo we can use the model to accurately predict how the amplifier will work in a circuit.


1) Measure the transfer function, Avo, of the amplifier in the following manner. 2) Determine the input resistance Ri of the amplifier model circuit (that is the resistance from point A to ground). 3) Determine the output resistance Ro. 4) A capacitor will block DC voltages. 5) Biasing the amplifier.

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