Power Added Efficiency

Conversion Ratio Calculation

Standard DC-to-RF conversion efficiency formulas ignore input drive power, which overstates amplifier performance when stage gain is moderate or low. Calculating power added efficiency accounts for RF drive energy supplied by driver stages, providing a complete system-level conversion picture. As amplifiers approach gain compression, output power increases while gain drops, creating a distinct peak efficiency operating point.

Operating near this peak maximizes battery life in wireless transmitters but increases intermodulation distortion levels.

Low Gain Boundary

When amplifier power gain approaches unity, the net RF power added drops toward zero regardless of DC power consumption. At low gain levels, traditional efficiency metrics diverge drastically from power added efficiency, making drive power inclusion critical.

Thermal Budget Impact

Unconverted DC energy degrades into heat within semiconductor active regions, driving up junction temperatures. High power added efficiency figures reduce cooling infrastructure needs and improve long-term hardware reliability in dense enclosures.