Optimal Driving Signal Extraction for Maximum Efficiency of Dual-Input High Power Amplifiers

Abstract

Dual-input single-output (DISO) radio frequency (RF) power amplifiers (PAs) have gathered significant interest for highly efficient amplification of modulated signals. DISO PAs provide advantages over their single-input single-output (SISO) counterparts, both for design and operation. However, contrary to SISO, driving DISO PAs requires an extraction of the optimum driving signals to maximize the power-added efficiency (PAE), and some input conditions can easily make the PA operate in a nonsafe region. This article presents algorithms to safely derive these optimal input signals. Two types of algorithms are proposed, which are dubbed “exploration” and “extraction”; the exploration algorithm finds a safe operation region of the DISO PA from minimal a priori information on the device under test; the extraction algorithm finds the optimal input drive from the exploration algorithm data. These algorithms are tested and validated in simulation and measurement for different DISO PA architectures.