Phase-Only Multilevel LINC Architecture for Linearizing Chireix Outphasing Power Amplifiers

This letter presents a distinct approach to linearize Chireix outphasing power amplifiers (PAs), which is leveraging the multilevel linear-amplification-with-nonlinear-components (LINC) concept. The proposed architecture operates only on phase-modulated signals and is therefore compatible with digital-like signal generation and distribution. The analysis of the architecture and a calibration algorithm are presented. The validity of the proposed concept is verified by the implementation of a prototype operating at 3.5 GHz, providing 42 dBm of peak output power. The prototype achieves −40.8 and −39.4 dB adjacent channel leakage ratio (ACLR) and 1.73% and 1.94% error vector magnitude (EVM) for a 64- quadrature amplitude modulation (QAM) modulated signal with 6.5 dB PAPR at 10 and 20 MHz bandwidth (BW), respectively. For an orthogonal frequency-division multiplexing (OFDM) modulated signal with 8.3 dB PAPR at 10 MHz BW, the ACLR and EVM are −40.2 dB and 2.64%, respectively.