Crossover Distortion in Amplifiers: Identify which amplifier class typically exhibits crossover distortion behavior.
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Aclass A O/P stage
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Bclass B O/P stage
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Cclass AB output stage
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Dcommon pulse O/P state
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Eclass C output stage
Answer
Correct Answer: class B O/P stage
Explanation
Introduction / Context:Crossover distortion is a common non-linearity in amplifier circuits. It appears near the zero-crossing of the input signal, particularly in push–pull output stages. Understanding which class of amplifier exhibits this distortion helps in selecting proper biasing techniques.
Given Data / Assumptions:
- Four amplifier classes given: A, B, AB, and an unrelated term 'common pulse.'
- We want to identify which one characteristically shows crossover distortion.
Concept / Approach:
Class B amplifiers conduct for exactly 180° of the input cycle per transistor. Near the zero crossing, both transistors are off briefly due to base–emitter voltage requirements, leading to distortion called 'crossover distortion.'
Step-by-Step Solution:
Class A: Device conducts for full 360°, highly linear, no crossover distortion.Class B: Each device conducts for 180°, gap around zero crossing causes crossover distortion.Class AB: Devices conduct for slightly more than 180°, reducing but not eliminating crossover distortion.Class C: Not listed in the options but typically conducts less than 180°, unsuitable for linear amplification.Verification / Alternative check:
Practical push–pull Class B designs exhibit crossover distortion unless biasing (Class AB) is applied to minimize it. Audio engineers frequently discuss this issue in amplifier design.
Why Other Options Are Wrong:
- Class A: No crossover distortion.
- Class AB: Reduces distortion significantly but not characteristic.
- 'Common pulse' is irrelevant and incorrect.
Common Pitfalls:
- Confusing harmonic distortion (common in Class C) with crossover distortion (specific to Class B).
- Assuming all amplifier classes exhibit it equally.
Final Answer:
class B O/P stage