How is the efficiency of an RF power amplifier determined?
Divide the DC input power by the DC output power
Divide the RF output power by the DC input power✓Correct answer
Multiply the RF input power by the reciprocal of the RF output power
Add the RF input power to the DC output power
Explanation
Efficiency is useful output divided by the power supplied, so for an RF power amplifier it is RF output power divided by DC input power. Reversing that ratio would normally produce a value greater than one and cannot represent efficiency.