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141 results on '"Liu, Rui Jia"'

16. A Gallium Nitride (GaN) Doherty power amplifier chip design based on series RC stability network.

Author

Li, Chang‐Kun, Zhu, Xiao‐Wei, Liu, Rui‐Jia, and Zhang, Lei

Subjects
GALLIUM nitride, POWER amplifiers, ELECTRIC capacity, DESIGN
Abstract

Summary: This paper presents Doherty power amplifier (DPA) based on gallium nitride (GaN) technology, incorporating a parallel grounded network with series RC elements in front of the carrier and peaking amplifiers to enhance circuit stability. In comparison to the traditional series network with parallel RC structure, this configuration effectively reduces the sensitivity of the stability factor K to the capacitance value within the stability network. Consequently, it mitigates the impact on various performance indicators such as gain and drain efficiency, addressing the issue of measurement performance deviation caused by inaccurate capacitance models in the simulation files, which is particularly crucial for DPA. As a result, the circuit exhibits improved consistency in design and processing. With full band stability, the DPA achieves a saturation output power of approximately 29.8 dBm at 28 GHz, a saturation efficiency of 38.2%, and a 6‐dB back‐off efficiency of 29.6%. [ABSTRACT FROM AUTHOR]

Published
2024
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25. A 23–29.5 GHz three‐stage mm‐wave GaN power amplifier using arbitrary two‐port complex‐impedance matching method.

Author

Zhao, Zi‐Ming, Zhu, Xiao‐Wei, Xia, Jing, Liu, Rui‐Jia, Dong, Qin, Chen, Peng, Zhang, Lei, Jiang, Xin, Yu, Chao, and Hong, Wei

Subjects
POWER amplifiers, GALLIUM nitride, INTEGRATED circuits
Abstract

Summary: This paper presents a broadband monolithic millimeter‐wave integrated circuit GaN power amplifier (PA) with arbitrary two‐port complex‐impedance matching method. The proposed matching topology has been applied to interstage matching network design by modifying traditional coupling matrix and synthesizing a desired network. The optimum load traction technique is introduced to provide some more suitable Zopts. After continuous‐wave test, the three‐stage MMIC PA achieves a peak PAE of 39.1% with a 34.9 dBm output power from 23 to 29.5 GHz and the measured S21 is 32.5 dB with a ±2.5 dB gain variation. When driven by a 400 MHz OFDM modulation signal with a PAPR of 8.5 dB, the measured ACPR is improved to −40.6/−40.7 dBc with DPD. In this case, the PA achieves an average PAE of 11.7% and a 26.7 dBm average output power. [ABSTRACT FROM AUTHOR]

Published
2023
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31. An Optimization Method for Load Modulation Trajectories in a Millimeter-Wave GaN MMIC Doherty Power Amplifier Design

Author

Chen, Peng, Liu, Rui-Jia, Yu, Luqi, Zhao, Ziming, Zhu, Xiao-Wei, Hou, Debin, Chen, Jixin, Yu, Chao, and Hong, Wei

Abstract

The contribution of this brief is proposing an optimization method for load modulation trajectories of the Carrier and Peaking transistors based on shared load-pull contours. Firstly, theoretical analysis reveals that the load modulation trajectories can be expressed as a function of the back-off coefficient, the combining load and the output power. Taking the modulation interaction into consideration, the proposed method is then implemented in shared load-pull contours to demonstrate the optimization of load modulation trajectories. To validate the proposed method, a 25-26.5 GHz gallium nitride (GaN) microwave monolithic integrated circuit (MMIC) Doherty power amplifier (DPA) is realized by matching with the optimum load modulation trajectories. Measured results show that the DPA achieves saturated PAE higher than 29%, and 6 dB back-off PAE higher than 27%, with a saturated output power higher than 28.9 dBm across the band. To characterize the linearity, the DPA is measured using a 400 MHz modulated signal and digital predistortion (DPD).

Published
2024
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50. Microstructure, electrical conductivity and mechanical properties of a novel MAB phase Cr2AlB2 reinforced Cu-matrix composites.

Author

Wang, Ying, Yang, Ling Xu, Liu, Rui Jia, Liu, Hui Jun, Chi, Xiang, Zeng, Chao Liu, and Fu, Chao

Subjects
ELECTRIC conductivity, MICROSTRUCTURE, VICKERS hardness, INTERFACIAL bonding, GRAIN size, POWDERS
Abstract

Here, we report for the first time, a novel CrB/Cu(Al) composite is successfully fabricated by hot-pressed sintering of Cu and MAB phase Cr2AlB2 powders, which was prepared by a two-step molten salt method. The microstructure, mechanical properties and electrical conductivity of the composites were also investigated. Results show that homogeneous and compact composites composed of CrB and Cu (Al) solid solution are obtained, and the grain size of Cu matrix dramatically decreases from 56.41 to ~ 3 μm when Cr2AlB2 was added into Cu matrix. In addition, an alternate structure and good interfacial bonding between ceramic and Cu matrix are observed, which are beneficial for ceramic particles to bear loads and result in high mechanical strength. The Vickers hardness of Cu–20Cr2AlB2 composite is around 140 HV1.0 with electrical conductivity of 20.69% IACS. The tensile and yield strength of the composite are as high as 393.56–289.65 MPa, respectively. [ABSTRACT FROM AUTHOR]

Published
2022
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