High-Power BAW-Based FDD Front-End using Indirect-Duplexing Load Modulated Balanced Amplifier for Massive MIMO Array

This paper reports a novel high-power frequency-division duplex (FDD) front-end based on indirect-duplexing load modulated balanced amplifier (LMBA) with integrated bulk acoustic wave (BAW) filters, strongly facilitating the integration into emerging array-based systems. By transforming the BAW device from the antenna interface to the output of control amplifier (CA) together with the intrinsic signal-routing capability of quadrature coupler, the functionality of simultaneous transmission and reception (STAR) is maintained from the standard cavity-based high-power duplexing front-end. More importantly, the size, weight, and cost of the proposed solution are minimized. A commercial BAW Band1/3 quadplexer is integrated with a GaN-based pseudo-Doherty LMBA, achieving ≈60% and ≈43% of PA efficiency at peak power and 10-dB power back-off, respectively, and low reception loss close to the standalone quadplexer response in modulated measurement.