Load-Modulation-Based IMD3 Cancellation for Millimeter-Wave Class-B CMOS Power Amplifiers Achieving EVM < 1.2%

Journal article (2022)

Authors

M. Pashaeifar Electronics - EEMCS
L.C.N. de Vreede Electronics - EEMCS
S.M. Alavi Electronics - EEMCS
Research Group
Electronics (EEMCS) (TU Delft)
Copyright: © 2022 M. Pashaeifar, L.C.N. de Vreede, S.M. Alavi
DOI: https://doi.org/10.1109/LMWC.2022.3166257
Millimeter-wave OFDM Intermodulation distortion Logic gates Modulation Doherty Linearity Load modulation Power generation Wireless communication 5G mobile communication 5G New Radio (NR) Power amplifiers (PAs).
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Published Date

2022

Language

English

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Faculty

Electrical Engineering, Mathematics and Computer Science

Department

Microelectronics

Research Group

Electronics

Abstract

This letter presents a novel load-modulation-based 3rd-order intermodulation distortion (IMD3) cancellation technique for class-B CMOS power amplifiers (PAs). In a class-B PA, the IMD3 generated by the 3rd-order transconductance ( $g_{m3}$ ) and the gain compression have opposite signs, and thus, they can cancel each other at specific bias and loading conditions. The proposed Doherty topology allows adjusting the gain compression by modulating the effective loading, facilitating IMD3 cancellation over the entire load modulation region. The proposed approach is verified using a 28 GHz 40 nm CMOS series-Doherty PA (DPA) topology. The experimental result demonstrates 10/17 dB IMD3 improvement compared to class-B/DPA operation. Without using any digital pre-distortion, the measured EVM of the proposed technique for a 50 MHz 64-QAM OFDM signal with 8.9 dBm average output power is -38.7 dB (1.2%), which is 5.7/11 dB better than a standard class-B/DPA operation.