Lab 4 - EE 420L
Author: Victor Payumo
Date: February 26, 2020
Op-amps II, gain-bandwidth product and slewing
Experiment 1:
- Estimate, using the datasheet, the bandwidths for non-inverting op-amp topologies having gains of 1, 5, and 10.
- Experimentally verify these estimates assuming a common-mode voltage of 2.5 V.
- Your
report should provide schematics of the topologies you are using for
experimental verification along with scope pictures/results.
- Associated comments should include reasons for any differences between your estimates and experimental results.
- Repeat these steps using the inverting op-amp topology having gains of -1, -5, and -10.
According to the datasheet, for unity the GBW is 1.3 MHz.
Non-inverting case:
BW = GBW / |Gain|
| Gain | Bandwidth |
| 1 | 1.3 MHz |
| 5 | 260 KHz |
| 10 | 130 KHz |
Inverting case:
BW = f unity / 1 + (Rf/Ri)
| Gain | Bandwidth |
| -1 | 650 KHz |
| -5 | 216 KHz |
| -10 | 118 KHz |
An input signal of 100 mV pp was used for every experiment
Non-inverting gain of 1:
Non-inverting gain of 5:
Ri = 10k, Rf = 40k
Non-inverting gain of 10:
Rf = 90k, Ri = 10k
Results
| Gain | Experimental | Calculated |
| 1 | 1.2 MHz | 1.3 MHz |
| 5 | 219 KHz | 260 KHz |
| 10 | 93 KHz | 130KHz |
Inverting gain of -1:
Rf = 10k, Ri = 10k
Inverting gain of -5:
Rf = 40k, Ri = 10k
Inverting gain of -10:
Rf = 90k Ri = 10k
| Gain | Experimental | Calculated |
| -1 | 655 KHz | 650 KHz |
| -5 | 198 KHz | 216 KHz |
| -10 | 80 KHz | 118Khz |
Experiment 2:
- Design
two circuits for measuring the slew-rate of the LM324. One circuit
should use a pulse input while the other should use a sinewave input.
- Provide comments to support your design decisions.
- Comment on any differences between your measurements and the datasheet’s specifications.
760 mV / 2.081 us = .365 V/us = ~.4 V/us
Square wave
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