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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 back-off 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.