What conditions characterize common-mode operation _______________?
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Answer: C. an identical signal appears on both the inputs
Explanation
Common mode operation occurs when identical voltages arrive simultaneously at both the inverting and noninverting inputs. Because the input voltages are identical, their difference is theoretically zero under perfectly matched circuit conditions. Differential amplifiers are specifically designed to reject these identical input components while amplifying differences. Differential amplifiers consist of paired transistors designed to respond primarily to voltage differences between inputs. External electromagnetic interference often couples equally onto both input wires acting as a common mode signal. The ability of an amplifier to reject this identical voltage determines its overall common mode rejection ratio.
Grounded inputs represent a testing condition for offset voltage rather than the definition of common mode operation. Connecting amplifier outputs together can cause severe short circuits and damage internal transistor stages. Having output signals in phase describes general signal propagation rather than the specific dual input condition.
- Subject
- Engineering
- Category
- Electrical Engineering
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- —
- Difficulty
- medium
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