Question
Why are switching amplifiers more efficient than linear amplifiers?
Answer Options
- A) Switching amplifiers operate at higher voltages
- B) The switching device is at saturation or cutoff most of the time
- C) Linear amplifiers have high gain resulting in higher harmonic content
- D) Switching amplifiers use push-pull circuits
Correct Answer: B
Explanation
Amplifier efficiency is defined by the ratio of output power to DC input power, with the difference being heat dissipated by the active device. In linear amplifiers (A, B, AB), the active device acts as a variable resistor, dissipating significant power as heat while conducting. Switching amplifiers (Class D, E, F) minimize this heat generation.
Switching amplifiers are more efficient because the switching device is at saturation or cutoff most of the time. In saturation (fully ‘on’), the voltage drop across the switch is near zero, and in cutoff (fully ‘off’), the current is near zero. Since power dissipation is P=I \times V, keeping one of these factors near zero minimizes wasted heat, leading to theoretical efficiencies of 90\% or more.
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