Analog and electronic circuits

Compared with a class A amplifier, which is a characteristic of a class B push-pull amplifier?

  1. ALow efficiency but very low distortion
  2. BIt always conducts a large bias current
  3. CHigh power efficiency (theoretical maximum about 78.5%), but prone to crossover distortion
Show answer and explanation

Answer: C. High power efficiency (theoretical maximum about 78.5%), but prone to crossover distortion

Class A always conducts a large bias current, so distortion is low, but its theoretical maximum efficiency is low: 25% with a resistive load (50% with transformer coupling). Class B draws almost no current without a signal, so its efficiency is high, with a theoretical maximum of about 78.5% (π/4), but it is prone to crossover distortion.

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