What term describes the ratio of output power to DC input power of an amplifier?

"Efficiency" in an amplifier is the mathematical ratio of the useful RF output power to the DC input power required to run the circuit. It tells you how well the amplifier converts DC power from your power supply into useful radio frequency energy. No practical amplifier is 100 percent efficient because some of the DC input power is always lost as heat. For example, if an amplifier draws 100 watts of DC power and produces 50 watts of RF output, its efficiency is 50 percent. This is completely different from "gain," which compares the input signal to the output signal. Distractors like dynamic range refer to the span between the weakest and strongest signals a receiver can handle, not power ratios.