Exam-style question
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In a summing amplifier using an inverting configuration, how does phase inversion affect the combined output?.
- A.All input signals are summed with inverted polarity
- B.Only one input is inverted
- C.Inputs are summed without inversion
- D.Outputs are phase shifted by 90°
Model answer
What a good answer should say
- All input signals are summed with inverted polarity
Explanation
Why this works
Formula: Vout = - (Rf/Rin) * (V1 + V2 + …). Substitution: Each input voltage is multiplied by the negative sign.
Working: The negative sign inverts each input before summation, so the final output is the inverted sum. Answer: All input signals are summed with inverted polarity.
Conclusion: Phase inversion applies to every input in an inverting summing amplifier.
Common mistake
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