Keywords

LMBA, Balanced amplifier, Doherty power amplifier, linearity, load mismatch, reconfigurable.

Abstract

The rapid evolution of 5G and forthcoming 6G networks demands higher data rates and lower latency within increasingly congested spectrum resources. Advanced modulation schemes such as high-order quadrature amplitude modulation (QAM) and orthogonal frequency-division multiplexing (OFDM) have been widely adopted to improve spectral efficiency; however, these techniques substantially increase the peak-to-average-power ratio (PAPR) of transmitted signals. To enable power amplifiers (PAs) to operate efficiently under this conditions, load-modulated balanced amplifiers (LMBAs) have been developed as an effective solution while inherently supporting broadband operation. On the other hand, the deployment of massive multiple-input multiple-output (MIMO) technology and highly integrated active-antenna systems plays a crucial role in 5G communication, significantly boosting user capacity and spectrum efficiency. However, this array based system faces challenges due to the dense packing of antenna arrays, leading to a strong mutual coupling among the antenna elements. This effect leads to significant variations in antenna scan impedance during beam steering, with the voltage standing-wave ratio (VSWR) reach up to 6 : 1. Such impedance fluctuations directly impact the performance of power amplifiers (PAs) and can cause system level degradation such as main beam distortion. To address aforementioned challenges, a one-dimensional reconfigurable pseudo-Doherty LMBA is proposed, achieving broadband VSWR resilience through a single bias-control reconfiguration. Next, a hybrid asymmetrical LMBA is proposed to enable efficient and linear operation under mismatch through a load dependent reconfiguration. Finally, a double balanced LMBA topology is introduced, providing intrinsic load isolation which eliminate the undesired magnetic components or active reconfiguration

Completion Date

2025

Semester

Fall

Committee Chair

Chen, Kenle

Degree

Doctor of Philosophy (Ph.D.)

College

College of Engineering and Computer Science

Department

Electrical and Computer Engineering

Identifier

DP0029806

Document Type

Thesis

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