A High-Power Broadband Multi-Primary DAT-Based Doherty Power Amplifier for mm-Wave 5G Applications

• Published in: IEEE journal of solid-state circuits Vol. 56; no. 6; pp. 1668 - 1681
• Main Authors: Wang, Fei, Wang, Hua
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: 5G mobile communication; 5G New Radio (NR); Broadband; distributed active transformer (DAT); Doherty; efficiency enhancement; front-end module (FEM); Impedance; Inverters; linearity; Millimeter waves; millimeter-wave (mm-Wave) peak-to-average power ratio (PAPR); Modulation; Orthogonal Frequency Division Multiplexing; Peak to average power ratio; power amplifier (PA); Power amplifiers; power back-off (PBO); Silicon; System-on-chip; Transformers
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2021.3070800

Silicon-based millimeter-wave (mm-Wave) power amplifiers (PAs) with high power and high peak/back-off efficiency are highly desired to efficiently amplify multi-Gb/s 5G NR signals. This article presents a fully integrated high-power broadband linear Doherty PA with multi-primary distributed-active-transformer (DAT) power combining. We introduce a transformer-based impedance inverter for active load modulation and a multi-primary DAT structure for hybrid series and parallel power combining. Based on this, we propose a transformer-based Doherty combiner with more design freedom and a multi-primary DAT-based Doherty PA for simultaneous active load modulation and low-loss power combining. The EM simulation results demonstrate that the proposed DAT-based Doherty output network achieves very symmetric and balanced load impedances among all the main and auxiliary PA ports. As a proof of concept, a 24-30-GHz prototype PA is implemented in a 0.13-<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> SiGe BiCMOS process. The PA achieves 30.4% PAE max , 28.3-dBm <inline-formula> <tex-math notation="LaTeX">P_{\mathrm {sat}} </tex-math></inline-formula>, 30.2% PAE at 26.8-dBm <inline-formula> <tex-math notation="LaTeX">P_{\mathrm {1\,dB}} </tex-math></inline-formula>, and 21.2% PAE at 6-dB back-off from <inline-formula> <tex-math notation="LaTeX">P_{\mathrm {sat}} </tex-math></inline-formula> at 28 GHz. Modulation measurement with single-carrier 64-QAM signals and 5G NR FR2 orthogonal frequency-division multiplexing (OFDM) signals has been demonstrated. For a 200-MHz 1-CC 5G NR FR2 64-QAM signal, the PA achieves 18.1-dBm P avg and 13.8% PAE avg with −25.1-dB rms EVM at 28 GHz.