When you have completed this exercise, you will be able to relate the gain and bandwidth of an op amp

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Baldwin McDaniel
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1 Op Amp Fundamentals When you have completed this exercise, you will be able to relate the gain and bandwidth of an op amp In general, the parameters are interactive. However, in this unit, circuit input waveforms will not force the op amp into slew rate limitations. Slew rate will be examined in later units. The gain of an inverting circuit multiplied by circuit bandwidth equals the GBW product of the circuit op amp. Since B and gain are related as a product, the B of a circuit can be calculated by the following equation. gain of 50, what is the circuit bandwidth? a. 1 MHz b. 50 khz c. 20 khz d. 1 Hz 58 FACET by Lab-Volt

2 Op Amp Fundamentals maximum circuit gain? a. 0.1 b. 10 c. 100 d circuit feedback resistor. C C equals the value of R F. initial value. FACET by Lab-Volt 59

1.414 V pk-pk As the input signal frequency of the circuit changes, circuit gain a. increases as the frequency decreases. b. decreases as the frequency increases.

3 Op Amp Fundamentals EO IO EO can be stated in peak or peak-to-peak units. If a circuit has an initial output voltage of 1 V pk-pk, what is the expected voltage at the circuit breakpoint? a V pk b V pk-pk c V pk d V pk-pk As the input signal frequency of the circuit changes, circuit gain a. increases as the frequency decreases. b. decreases as the frequency increases. c. Both of the above. d. None of the above. Locate the INVERTING AMPLIFIER circuit block, and connect the circuit shown. Use R4 to null the circuit output voltage. After the nulling operation, do not offset the R4 TRIM control. 60 FACET by Lab-Volt

4 Op Amp Fundamentals Connect a sine wave generator to the input of your circuit. Make sure that R1 is connected into your circuit. Connect channel 1 of your oscilloscope to the input of your circuit. Connect channel 2 to the circuit output. Adjust the generator for a circuit output voltage of 10 V pk-pk at 1000 Hz. FACET by Lab-Volt 61

Op Amp Fundamentals Slowly increase the generator frequency until the peak-to-peak output voltage amplitude is 3 pk-pk pk-pk Maintain a constant level input voltage as you adjust the generator

5 Op Amp Fundamentals Slowly increase the generator frequency until the peak-to-peak output voltage amplitude is 3 pk-pk pk-pk Maintain a constant level input voltage as you adjust the generator frequency. Bandwidth = Recall Value 1 Move the R1 two-post connector to the R2 side of your circuit. Set the circuit output voltage at 10 V pk-pk at a frequency of 1000 Hz. The circuit gain is decreased from 100 to 10. Use the generator to determine the new bandwidth frequency of your circuit. Slowly increase the generator frequency while maintaining constant circuit input voltage. o equals 7.07 V. Bandwidth = Recall Value 2 62 FACET by Lab-Volt

6 Op Amp Fundamentals Compare the frequency of your circuit output Recall Value 2 Recall Value 1 Based on your comparison, the circuit bandwidth a. increased as the circuit gain decreased. b. was not affected by a change in circuit gain. c. decreased as the circuit gain decreased. d. None of the above. Return the circuit output voltage to 10 V pk-pk at a frequency of 1000 Hz. Place CM switch 12 in the ON position to place a 0.01 F capacitor across the circuit feedback resistor. gain-of-100 circuit bandwidth = gain-of-10 circuit bandwidth = Recall Value 1 Recall Value 2 Based on the circuit breakpoint, does this change increase or decrease the circuit bandwidth? a. increase b. decrease FACET by Lab-Volt 63

7 Op Amp Fundamentals Increasing circuit gain decreases circuit bandwidth. Adding a capacitor across the circuit feedback resistor reduces the circuit bandwidth. 1. a. dc gain. b. ac gain. c. slew rate. d. bandwidth. 2. a. 0 V. b times the initial output voltage. c. 0.5 times the initial output voltage. d. None of the above. 3. Locate the INVERTING AMPLIFIER circuit block and connect the circuit shown. Make sure that the circuit is trimmed. When trimming your circuit, remember to connect the circuit input to common. Place CM switch 11 in the ON position to modify the circuit gain. Set the sine wave generator for 1000 Hz and 0.1 V. What is the circuit gain? a. 0.1 b. 1 c. 10 d FACET by Lab-Volt

8 Op Amp Fundamentals 4. Monitor the circuit output voltage as you increase the input signal frequency to about 20 khz. Maintain a constant circuit input voltage. Based on the output voltage, a. the GBW product of U1 is about 100 khz. b. circuit bandwidth is about 100 khz. c. you cannot determine circuit bandwidth. d. the GBW product of U1 and the circuit bandwidth are about the same. 5. Place CM switch 11 in the OFF position. The circuit output voltage amplitude decreases because a. circuit gain increases and reduces the bandwidth. b. circuit gain increases and increases the bandwidth. c. d. None of the above. FACET by Lab-Volt 65

Schmitt trigger. V I is converted from a sine wave into a square wave. V O switches between +V SAT SAT and is in phase with V I.

When you have completed this exercise, you will be able to operate a sine wave to square wave converter. You will verify your results with an oscilloscope. Schmitt trigger. V I is converted from a sine