An X-Band Pulsed Load Modulation Transmitter With Multilevel Envelope Delta-Sigma Modulations

Yonghoon Song, Rui Zhu, Yuanxun Ethan Wang

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Switched mode RF power amplifiers (PAs) under bitstream modulations, such as bandpass or envelope delta-sigma modulations (EDSMs), have received increasing attentions over the past years. Such amplifiers offer high power efficiencies under power back-off conditions with pulse train voltage waveforms yet maintain their linearity in amplification through digital coding and modulations. This paper presented an X-band switched mode PA based on the pulsed load modulation (PLM) technique with multilevel EDSM to realize broadband efficient amplification of nonconstant-envelope signals. The complete theory of power efficiency for PLM under three-level EDSM is presented. The X-band PA is implemented with 0.25- μm discrete GaN transistors from Triquint. Both two-level and three-level EDSM techniques were tested and compared in regard to their quantization noise levels and power efficiencies. Under the three-level EDSM, the PA delivered 34.6-dBm output power for a WCDMA uplink signal with 100-MHz bandwidth and 5.3-dB peak-to-average power ratio at the carrier frequency of 9.2 GHz. The measured drain efficiency and the power-added efficiency with the modulation were 34.6% and 26.5%, respectively. The adjacent channel leakage power ratio at the output was measured to be 32.2/32.3 dBc at the 100-MHz offsets without using digital predistortion.

Original languageEnglish
Article number7565644
Pages (from-to)3643-3653
Number of pages11
JournalIEEE Transactions on Microwave Theory and Techniques
Volume64
Issue number11
DOIs
Publication statusPublished - Nov 2016
Externally publishedYes

Keywords

  • Bitstream modulations
  • GaN
  • X-band
  • envelope delta-sigma modulation (EDSM)
  • pulsed load modulation (PLM)
  • switched-mode power amplifiers (PAs)

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Song, Y., Zhu, R., & Wang, Y. E. (2016). An X-Band Pulsed Load Modulation Transmitter With Multilevel Envelope Delta-Sigma Modulations. IEEE Transactions on Microwave Theory and Techniques, 64(11), 3643-3653. Article 7565644. https://doi.org/10.1109/TMTT.2016.2604243