Explain the different classes of RF power amplifiers.

RF power amplifier classes differ in efficiency and linearity trade-offs. Class A: Conducts full cycle (360°), most linear but only 25-50% efficient; used for low-power linear applications. Class B: Conducts half cycle (180°), 78.5% max efficiency but has crossover distortion; push-pull configuration common. Class AB: Conducts slightly more than half cycle, compromise between A and B; common in base stations. Class C: Conducts less than half cycle, 80%+ efficient but non-linear; used for FM and switching. Class D/E/F: Switching amplifiers with 90%+ efficiency; Class E popular for RF with ZVS/ZCS. Modern systems use Doherty amplifiers combining classes for efficiency at back-off.