Class A, B, AB and D trade efficiency against distortion.
Class A conducts for 360° (linear, ≈25% efficient), B for 180° per transistor (≈78% max; crossover distortion), AB blends them, D uses PWM switching (>90%). Heat sinks, thermal design and SOA matter. Output stages must drive low-impedance loads.
A class D amplifier in a Bluetooth speaker wastes little energy as heat.
Power amplifiers drive loudspeakers and motors, and their class decides the trade-off between efficiency, heat and distortion.
Class A, B, AB and D trade efficiency against distortion.
Power amplifiers drive loudspeakers and motors, and their class decides the trade-off between efficiency, heat and distortion.
Class A conducts all the time and has low distortion but poor efficiency, while class B conducts half the time, has better efficiency and suffers crossover distortion.
Its output devices switch fully on and off, so they dissipate little power, which allows high efficiency and small heatsinks.
Typical applications include selecting a class D amplifier for a battery-powered speaker, choosing a class AB output stage for an audio system with low distortion and designing a power stage to drive a 4 ohm load with high output power.
Study "Frequency response of amplifiers" first (topic 27 of 104 in Electronics & Embedded). It covers the groundwork this topic builds on.
Complementary push-pull. Quiescent current. Class D for portable audio.
A class D amplifier in a Bluetooth speaker wastes little energy as heat.
The next topic is "Voltage regulators", which builds directly on this one.
It is classed as Beginner in Electronics & Embedded (topic 28 of 104). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.
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