Question
For what portion of the signal cycle does each active element in a push-pull, Class AB amplifier conduct?
Answer Options
- A) More than 180 degrees but less than 360 degrees
- B) Exactly 180 degrees
- C) The entire cycle
- D) Less than 180 degrees
Correct Answer: A
Explanation
Amplifier classes of operation (A, B, AB, C) describe how the active devices (transistors or tubes) are biased, which dictates the portion of the input signal cycle during which they conduct current. This, in turn, determines the amplifier’s efficiency and linearity.
In a push-pull, Class AB amplifier, the active devices are biased slightly past the cutoff point. Each device conducts for more than 180 degrees but less than 360 degrees of the input signal cycle. This small overlap minimizes the crossover distortion found in Class B amplifiers while keeping the overall efficiency higher than a pure Class A amplifier, making Class AB the standard for linear SSB (voice) power amplification.
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