Antenna-VSWR-Resilient Load-Modulated Balanced Amplifier (LMBA) for Massive MIMO Communications

Load modulation has been a compelling technology for high-efficiency transmission of spectrally-efficient modulated signals. However, conventional architectures such as Doherty power amplifiers (PAs) are restricted by narrow bandwidth, limited dynamic range, and high sensitivity to load impedance mismatch. In this presentation, I will introduce a new family of load-modulation PAs based on quadrature-balanced topology, namely load-modulated balanced amplifier (LMBA). This seminar will also uncover a new theoretical framework and design methodology for LMBA based on signal-flow graph. Together with versatile carrier/peaking biasing schemes, various LMBA modes are developed and demonstrated, achieving extended power backoff range, unprecedented efficiency, literally unlimited bandwidth, and intrinsic linearity. Moreover, LMBA is able to inherit the balanced nature and achieve strong resilience to load variations, and a novel architecture of load-modulated double-balanced amplifier (LMDBA) will be presented for validation. This innovation holds promise for eliminating the need for magnetic circulators that are widely deployed in current 5G massive MIMO systems.