Fully Integrated CMOS PAs with Two-Winding and Single-Winding Combined Transformer for WLAN Applications

Se-Eun CHOI  Hyunjin AHN  Hyunsik RYU  Ilku NAM  Ockgoo LEE  

IEICE TRANSACTIONS on Electronics   Vol.E101-C   No.12   pp.931-941
Publication Date: 2018/12/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E101.C.931
Type of Manuscript: PAPER
Category: Microwaves, Millimeter-Waves
CMOS,  power amplifier (PA),  adaptive bias,  multi-gated transistors,  power-combining transformer,  

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Fully integrated CMOS power amplifiers (PAs) with a two-winding and single-winding combined transformer (TS transformer) are presented. The general analysis of the TS transformer and other power-combining transformers, i.e., the series-combining transformer and parallel-combining transformer, is presented in terms of the transformer design parameters. Compared with other power-combining transformers, the proposed power-combining TS transformer offers high-efficiency with a compact form factor. In addition, a fully integrated CMOS PA using the TS transformer with multi-gated transistors (MGTRs) and adaptive bias circuit has been proposed to improve linearity. The proposed PAs are implemented using 65-nm CMOS technology. The implemented PA with the TS transformer achieves a saturated output power of 26.7 dBm with drain efficiency (DE) of 47.7%. The PA achieves 20.13-dBm output power with 21.4% DE while satisfying the -25-dB error vector magnitude (EVM) requirement when tested with the WLAN 802.11g signal. The implemented PA using the TS transformer with MGTRs and adaptive bias circuit achieves the -30-dB EVM requirement up to an output power of 17.13 dBm with 10.43% DE when tested using the WLAN 802.11ac signal.