How Not to Rely on Moore's Law Alone: Low-Complexity Envelope-Tracking Amplifiers

Achieving fast wireless access speeds in an already restricted bandwidth (as the frequency spectrum is a finite resource) necessitates highly spectrally efficient communications standards that combine both amplitude-modulation (AM) and phase-modulation (PM). The resulting complex modulation schemes require that the RF power amplifier (PA) be highly linear to preserve the modulation and, hence, the transmitted data (in-band linearity) and simultaneously avoid interfering with users of the rest of the spectrum (out-of-band linearity). Unfortunately, in PA design, linearity and efficiency are contradictory goals; typically, highly linear PAs demonstrate low efficiency and, hence, reduced battery life [1].