Wideband Digital Power Amplifiers With Efficiency Improvement Using 40-nm LP CMOS Technology

H Qian, Jian Orion Liang, Xun Luo

Research output: Contribution to journalArticleScientificpeer-review

15 Citations (Scopus)


In this paper, two fully integrated digital power amplifiers (DPAs) intended for polar transmitters are proposed using a 40-nm CMOS technology, which achieve ultra wideband and high efficiency simultaneously. Firstly, the wideband Class-E power amplifier with nonideal characteristics is analyzed. Secondly, the design procedure of converting the nonideal Class-E model to a compact matching network is introduced for the on-chip implementation. Thirdly, the stacked-stepped-impedance transformer is utilized for the wideband output-matching network to improve the DPA power efficiency while tracking optimum load impedance. Finally, to enhance the saturated and back-off efficiency within a wideband, a novel feed-forward DPA architecture for a digital polar transmitter with multi-mode dynamic-matching (DM) network is firstly introduced and demonstrated. To verify the mechanism mentioned above, two DPAs are implemented and fabricated, which are the only reported wideband DPAs operating above 3 GHz with record fractional bandwidths, i.e., 92% and 100.8%, respectively. The proposed DPAs (i.e., DPA-I and DPA-II) exhibit peak output power of 22.2 and 22.3 dBm and peak drain efficiency of 46.2% and 47.4%, respectively, with a 1.2-V supply. In DM modes, the saturated and 6-dB back-off drain efficiency of DPA-II achieve maximum improvements of 7.5% and 5.7%, respectively. The core chip-sizes of the proposed DPAs (i.e., DPA-I and DPA-II) are 0.22 mm2 and 0.24 mm2, respectively.
Original languageEnglish
Pages (from-to)675-687
Number of pages13
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number3
Publication statusPublished - 1 Dec 2015


  • wideband
  • Class-E
  • digital power amplifier (DPA)
  • dynamic-matching (DM)
  • feed-forward
  • high efficiency
  • polar transmitter
  • stacked-stepped-impedance (SSI)
  • transformer


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