A Wideband Digital-Intensive Current-Mode Transmitter Line-Up

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Abstract

A current-mode direct-digital RF modulator (DDRM)-based transmitter (TX) architecture is proposed in this article for energy-efficient wireless applications. To demonstrate its key principles, a 2×13 bit demonstrator is implemented in a 40-nm CMOS technology. This DDRM can operate standalone or as a driver for a common-gate (CG)/common-base (CB) power amplifier (PA). The proposed DDRM is based on current-steering radio frequency digital-to-analog converters (RFDACs) that feature an extra current division path to allow the generation of the optimum current-mode class-B drive profile for the final CG/CB PA, facilitating energy-efficient TX operation without compromising linearity. For this purpose, the DDRM uses signed-IQ mapping combined with a class-B harmonic rejection (HR) technique. In addition, an advanced dynamic biasing technique is introduced to further enhance the TX line-up efficiency in deep power back-off (PBO) region. The DDRM driver standalone can provide 19.6-dBm RF peak output power. It supports a '160-MHz 256-QAM' signal at 2.4 GHz with an adjacent channel leakage ratio (ACLR) of -40.3 dBc and an error vector magnitude (EVM) of -33 dB, without using any digital pre-distortion (DPD). When connected to a CB SiGe PA, the overall TX line-up achieves an output power of 27 dBm and an overall TX system efficiency of 20%. This DPD-free TX line-up achieves an ACLR of -37.7 dBc and an EVM of -30 dB, respectively, when operating with an '80-MHz 64-QAM' signal at 2.2 GHz.

Original languageEnglish
Pages (from-to)2489-2500
Number of pages12
JournalIEEE Journal of Solid-State Circuits
Volume58
Issue number9
DOIs
Publication statusPublished - 2023

Bibliographical note

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care
Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Keywords

  • Common-gate (CG)/common-base (CB) power amplifier (PA)
  • current division path
  • digital pre-distortion (DPD)-free
  • direct-digital RF modulator (DDRM)
  • dynamic biasing
  • harmonic rejection (HR)
  • IQ-mapping
  • quadrature up-converter
  • radio frequency digital-to-analog converter (RFDAC)
  • TX line-up

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