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Experiment 3: “Operational Amplifier Circuit using a Single Voltage Source”ECE 3060, Section 002Tommy LaneLab Partner: Chris LamExperiment completed on:September 7th, 2016Date Submitted:September 19th, 2016Introduction:This experiment is being conducted to gain understanding of the AC and DC characteristics of an operational amplifier (op-amp) when operating with a single unipolar voltage source, such as, a 9 V battery. The objective is to design, construct, and verify the operation of an amplifier which meets the given specifications.Background:Op-amp output voltages are limited by the power rails, also known as, the power supply voltages. Many signals have both positive and negative values; therefore, it is common practice to put both a positive and a negative voltage source on the power supply inputs. Sometimes this is not easily accomplished while staying in the bounds of the project being worked on. Putting a DC offset of half the power supply voltage into the signal allows the signal to be shifted up by half the supply voltage. This allows for the output to have a plus and minus side, but the out put needs to be shifted back down so a decoupling capacitor is used on the output of the op-amp to remove the DC component of the signal. This lab intends to test how well this theory holds up.Procedure:Setup: a lab bench power supply with 12 V DC, a function generator with 1 kHz sinusoidal signal - no DC offset, and an oscilloscope with – preferably with two probes to measure the input and the output of the circuit at the same time. Build the circuit Cir1, from the appendix. Attach the function generator, and ch2 of the oscilloscope to the input of the op-amp. Attach the output of the op-amp to ch1 of the oscilloscope. Make sure the op-amp input is small enough to avoid clipping.Measure and record VIN, V+, V_, VO, and VOUT using the oscilloscope, make sure that the oscilloscope is set to DC coupling. This allows both the AC and the DC components of the signal to be read.Determine that gain at 1kHz. Using this as the nominal gain, determine the lower 3dB frequency by slowly reducing the frequency of the input signal coming from the function generator. The 3dB frequency will have been acquired when the output amplitude has fall to 0.707 of its original size.Now set the frequency back to 1 kHz and increase the amplitude until significant clipping is visible on the output. Record the waveform and measure the peak-to-peak output voltage. Then reduce the output until the clipping just disappears. Note the input amplitude at which the clippings begin for both the positive and for the negative portions of the waveform.Modify the circuit to reflect that of Cir2, found in the appendix. Repeat the previous step (measurement of clipping), and record all DC voltages on the circuit.Results, analysis, discussion:0125730000The circuit analysis for this lab was not difficult. Nor was the experiment. However, I did not expect the simulation results to match up to the experimental results quite so well. However, after further reviewing the lab requirements, the desired voltage gain of 9 V in the mid-band was not reached. Although when using very small input signals the output was close to the desired behavior. Summary and Conclusion:This experiment backed up what was discussed in class, and also circuit analysis theory, when using superposition theory with both AC and DC current simultaneously.References: No notable references other than those provided by TTU to do our lab.Appendix:Fig1Fig2Fig3Fig4Fig 5Fig 6Fig7Fig8Fig 9Fig 10Fig 11Fig 12 - significant slipping seen at output.Fig 13Fig 14Fig 14Cir 1 - V+ terminal reads 6 VCir 2 V+ ................
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