X-Band GaN Multi-Level Chireix Outphasing PA with a Discrete Supply Modulator MMIC

Abstract

This paper presents the characterization of a multi-level Chireix outphasing PA with a GaN discrete supply modulator MMIC at 9.7GHz. The internal PAs include class-F harmonic terminations, while the Chireix combiner determines the fundamental frequency load modulation. A power-DAC architecture provides 8 supply levels with 3 half-bridges, maintaining more than 85% efficiency. The combination of the two achieves a peak output power of 4.8W, and average total efficiencies for a 6dB PAR QPSK signal of 44.1% and 48.1% with and without considering the supply modulator consumption, respectively, demonstrating the feasibility of this PA architecture with a real discrete supply modulator.