Purpose:
To give you the chance in experimenting with basic op-amp circuits like inverting and non-inverting amplifiers, difference and adder circuits. The use of the LF411 will be the primary used op-amp for these exercises, in which are necessary for basic circuitry.
Procedure:
1) Build an inverting amplifier with a theoretical gain of -20 dB. Measure its frequency with a bode plot and compare with expected values. Find the corner frequency. Now replace the LF411 with its pin equivalent op-amp, the TL061, and repeat previous measurements.
2) Build a non-inverting amplifier and repeat measurements as done in part 1 of the procedure.
3) Build an adder circuit and take measurements using two different DC voltages, then verify that it works properly with the following relationship.
- \(V_{out}=-\left(V_1-\frac{1}{2}V_2\right)\)
4) Build a difference amplifier as shown in fig. 6.7 of your textbook, and verify that is operates as to be expected.
Data:
1) The materials used for the inverting amplifier circuit as shown in Fig. (1), included R1=10 kOhms, Rf=200 kOhms, and a gain B.W. = 3 MHz. The expected corner frequency was calculated by dividing the wide gain bandwidth by the expected gain.
- \(f_c=\frac{3x10^6\ Hz}{20\ dB}=150\ kHz\)
- \(f_{mc}=149871\ Hz\)
The measured corner frequency is very close to the expected calculations. Data was collected using LabVIEW and plotted with Python.
Now repeating the same measurements, but with the TL061 op-amp.
- \(f_c=\frac{1x10^6\ Hz}{20\ dB}\ =\ 50\ kHz\)
- \(f_{mc}=\ 30\ kHz\)
The difference in measured and expected corner frequencies for the TL061 op-amp is quite large, proving the LF411 to be of higher quality, and a prettier penny.