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AC Negative Feedback OpAmp Circuits
14 questions By Tony R. Kuphaldt
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Question 7 of 14
Some operational amplifiers are internally compensated, while others are externally compensated. Explain the difference between the two. Hint: examples of each include the classic LM741 and LM101 operational amplifiers. Research their respective datasheets to see what you find on compensation!
Reveal answerThe difference is the physical location of the compensating capacitor, whether it is a part of the integrated circuit or external to it.
Follow-up question: show how an external compensating capacitor may be connected to an opamp such as the LM101.
Notes:Ask your students to explain why we might wish to use either type of opamp when building a circuit. In what applications do they think an internally-compensated opamp would be better, and in what applications do they think an externally-compensated opamp would be preferable?
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Question 8 of 14
Define “Gain-Bandwidth Product” (GBW) as the term applies to operational amplifiers.
Reveal answerGBW product is a constant value for most operational amplifiers, equal to the open-loop gain of the opamp multiplied by the signal frequency at that gain.
Notes:There are other means of defining Gain-Bandwidth Product, so do not be surprised if students present alternative definitions during the discussion time.
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Question 9 of 14
Define “Unity-Gain Bandwidth” (B1) as the term applies to operational amplifiers.
Reveal answerUnity-Gain Bandwidth is the frequency at which an operational amplifier’s open-loop voltage gain is equal to 1.
Notes:It does not require a great deal of insight to recognize that unity-gain bandwidth (B1) and gain-bandwidth product (GBW) are pretty much the same thing. This would be a good point to bring up (in the form of a question!) for your students if you have already discussed GBW.
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- Parallel DC Circuits Practice Worksheet With Answers
