14-May-2015: Inverting Voltage Amplifier

PURPOSE

The purpose of this experiment was to implement an inverting voltage amplifier to an AC voltage.

PRE-LAB

Figure 1

Figure 2

Figure 3

We began this experiment by analyzing the circuit diagram shown above (Figure 1). We first converted the frequencies that we were going to use in the experiment into angular frequencies as shown in Figure 2. Then, we found the theoretical gains and phase shifts of the circuit with the equation displayed in Figure 3.

PROCEDURES

Figure 4

After completing our pre-lab exercises, we set up the circuit as shown above in Figure 4. We then applied a voltage with an amplitude of 2 V and a frequency of 100 Hz to the circuit. The resulting output voltage is shown in Figures 5 and 6. We then applied two more voltages with the same amplitude but with frequencies of 1 kHz, and 5 kHz, respectively. The resulting output voltages from these inputs are displayed in Figures 7 through 10.

Figure 5: Frequency at 100 Hz (input)

Figure 6: Frequency at 100 Hz (output)

Figure 7: Frequency at 1 kHz (input)

Figure 8: Frequency at 1 kHz (output)

Figure 9: Frequency at 5 kHz (input)

Figure 10: Frequency at 5 kHz (output)

Based on the graphs above, we were able to find the phase shift angles at each frequency. We were able to do this by dividing the time difference between the peaks of the input and output voltages by the period of the graphs and multiplying by 360 degrees (θ = Δt/T * 360°). We also found the gains by dividing the amplitude of the output voltage by the amplitude of the input voltage. These calculated values are shown in Figure 11.

Figure 11

Finally, we compared the theoretical values that we found in the pre-lab and compared them to the values that we found experimentally. The percent difference between these values are shown above in Figure 11. It can be seen from percent differences that our experimental values were pretty accurate.