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Erik G Larsson - One of the best experts on this subject based on the ideXlab platform.

Harish S. Krishnamoorthy - One of the best experts on this subject based on the ideXlab platform.

  • Multi-Phase Three-Level Buck Converter with Current Self-Balancing for High Bandwidth Envelope Tracking Power Supply
    2020 IEEE Applied Power Electronics Conference and Exposition (APEC), 2020
    Co-Authors: Srikanth Yerra, Harish S. Krishnamoorthy
    Abstract:

    Envelope Tracking (ET) is a power supply modulation technique for a radio frequency power amplifier (RFPA), primarily employed to improve its efficiency. This paper presents the design and performance analysis of a two-phase three–level buck converter, then compares it with its two-level counterpart for ET power supply application. Gallium Nitride (GaN) MOSFETs switching at 25 MHz are selected as power stage devices and Zero Voltage Switching (ZVS) technique is used for better efficiency. A fourth-order ZVS - low pass filter (LPF) is designed to track a 20 MHz large bandwidth Envelope Signal and also to maintain the current self-balancing in the multi–phase converter system. The efficiency of the proposed design peaks 97.5 % at 115 W and has an average efficiency of 94.5 % at 26 W. Simulation results evince precise tracking of 20 MHz, 4G LTE Envelope Signal with 10 dB Peak-to-Average Power Ratio (PAPR). Performance analysis indicates that the three-level option has improved average power efficiency for higher bandwidth ET applications.

Chengxiang Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Hysteresis Voltage Prediction Control for Multilevel Converter in the Series-Form Switch-Linear Hybrid Envelope Tracking Power Supply
    IEEE Transactions on Power Electronics, 2020
    Co-Authors: Xinbo Ruan, Yazhou Wang, Chengxiang Zhang
    Abstract:

    Switch-linear hybrid (SLH) Envelope tracking (ET) power supply can achieve high efficiency and high tracking bandwidth simultaneously, and it has two typical forms, namely, series-form and parallel-form. In the series-form SLH ET power supply, the switched-mode converter is expected to output a continuous-wave voltage which can track the load voltage accurately to enhance the overall efficiency, and the buck converter with hysteresis voltage control (HVC) can be utilized. However, the output voltage of the buck converter will go over the hysteresis voltage boundaries, degrading the linearity and efficiency of the ET power supply. In this article, the hysteresis voltage prediction control (HVPC) is proposed to mitigate the problem in the HVC for buck converter. Moreover, in order to further increase the efficiency, the multilevel converter (MLC) is adopted instead of the buck converter for reducing the switching frequency and the inductor root-mean-square current, and the corresponding HVPC control strategy is also proposed. A prototype of the series-form SLH ET power supply employing the MLC with HVPC aimed at 5-MHz Envelope Signal is fabricated in the lab. The measured overall efficiency is 77.5%, a 12% efficiency improvement over that using step-wave switched-mode converter.

Tumula V K Chaitanya - One of the best experts on this subject based on the ideXlab platform.

L E Larson - One of the best experts on this subject based on the ideXlab platform.

  • analysis of Envelope Signal injection for improvement of rf amplifier intermodulation distortion
    IEEE Journal of Solid-state Circuits, 2005
    Co-Authors: Vincent W Leung, Junxiong Deng, Prasad S Gudem, L E Larson
    Abstract:

    Adaptive bias techniques based on Envelope Signal power detection have been proposed for linearity enhancement and dc current reduction in RF amplifiers. Experimental results show an improvement in amplifier linearity, although asymmetric intermodulation distortion (IMD) was observed. This work rigorously studies the effects of the Envelope Signal injection on amplifier distortion using the Volterra series formulations. The results intuitively explain the spectral regrowth asymmetry, and point to a design technique in which third-order IMD can be optimally cancelled. The theory was verified through comparison to measurement and simulation results.

  • analysis of Envelope Signal injection for improvement of rf amplifier intermodulation distortion
    Custom Integrated Circuits Conference, 2004
    Co-Authors: Vincent W Leung, Junxiong Deng, Prasad S Gudem, L E Larson
    Abstract:

    Adaptive bias techniques based on Envelope Signal power detection have been proposed for linearity enhancement and DC current reduction in RF amplifiers. Experimental results show an improvement in amplifier linearity, although asymmetric intermodulation distortion (IMD) was observed. This paper studies the effects of the magnitude and phase of the Envelope Signal injection on amplifier linearity, and illustrates a technique in which the IMD can be optimally cancelled.