Which statement best describes the operation of a Class A amplifier?

• A. Output present throughout entire cycle and input never in cutoff.
• B. Output only during half of the cycle.
• C. Output only during a quarter of the cycle.
• D. Conduction angle of 180 degrees.

Answer: (A)

Class A amplification means the active device conducts for the full input cycle, so the output is produced for every part of the waveform. The bias is set so the transistor never goes into cutoff, which results in a conduction angle of 360 degrees. This continual conduction yields very linear amplification with low distortion because the device stays in its linear region throughout the entire cycle. The trade-off is efficiency: since current flows continuously even without an input signal, power conversion efficiency is lower than in other classes.