Learning Path
Question & Answer1
Understand Question2
Review Options3
Learn Explanation4
Explore TopicChoose the Best Answer
A
To prevent loading the previous stage of the circuit
B
To increase the power output
C
To reduce the noise in the signal
D
To allow for greater voltage swings
Understanding the Answer
Let's break down why this is correct
Answer
The main reason an op‑amp has a very high input impedance is that its input stage is built as a differential pair of transistors that are driven by a high‑impedance bias network. Because the transistors are arranged so that the base‑emitter junctions are reverse‑biased and the collector current is set by a current source, the effective resistance seen at the input terminals is extremely large. This design keeps the op‑amp from drawing current from the signal source, so it behaves almost like an open circuit. For example, when a 1 kΩ source is connected to the input, the op‑amp draws only microamps, leaving the source voltage largely unchanged. Thus, the high input impedance protects the signal source from loading.
Detailed Explanation
High input impedance means the op‑amp draws almost no current from the signal source. Other options are incorrect because Some think a high input impedance gives more power output, but power depends on the output stage, not the input; Noise is mainly from thermal fluctuations and amplifier design, not from input impedance.
Key Concepts
operational amplifier
input impedance
Topic
Operational Amplifiers Basics
Difficulty
medium level question
Cognitive Level
understand
Practice Similar Questions
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Question 1What is the primary reason for the high input impedance of an operational amplifier?
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Question 2In an operational amplifier, how does negative feedback influence the output signal in common applications such as amplifiers and filters?
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Question 3What is the primary reason an op-amp output might saturate when trying to amplify a signal?
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Question 4If an operational amplifier (op-amp) produces a very large output voltage when given a small difference between its inputs, what could be the underlying cause of this behavior?
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Question 5What is the primary reason for the high input impedance of an operational amplifier?
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Question 6In an operational amplifier, how does negative feedback influence the output signal in common applications such as amplifiers and filters?
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Question 7What is the primary reason an op-amp output might saturate when trying to amplify a signal?
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Question 8If an operational amplifier (op-amp) produces a very large output voltage when given a small difference between its inputs, what could be the underlying cause of this behavior?
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Question 9Which of the following components is primarily responsible for the high gain characteristic of an operational amplifier?
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