All-Digital LTE SAW-Less Transmitter With DSP-Based Programming of RX-Band Noise

Enrico Roverato, Marko Kosunen, Koen Cornelissens, Sofia Vatti, Paul Stynen, Kaoutar Bertrand, Teuvo Korhonen, Hans Samsom, Patrick Vandenameele, Jussi Ryynanen

Research output: Contribution to journalArticleScientificpeer-review

10 Citations (Scopus)
151 Downloads (Pure)

Abstract

We present the first all-digital LTE transmitter (TX) using programmable digital attenuation of receive band (RX-band) noise. The system is architectured to fully exploit the speed and low cost of DSP logic in deep-submicrometer CMOS processes, without increasing at all the design effort of the RF circuitry. To achieve operation without surface acoustic wave filter, the TX uses digital bandpass delta-sigma modulation and mismatch-shaping to attenuate the DAC noise at a programmable duplex distance. These functions can be implemented entirely within DSP, thus taking advantage of the standard digital design methodology. Furthermore, the fully digital RX-band noise shaping significantly relaxes the performance requirements on the RF front-end. Therefore, 10 bits of resolution for the D/A conversion are sufficient to achieve -160 dBc/Hz out-of-band (OOB) noise, without need for digital predistortion, calibration, or bulky analog filters. The TX was fabricated in 28-nm CMOS, and occupies only 0.82 mmsuperscript2. Besides low OOB noise, our system also demonstrates state-of-art linearity performance, with measured CIM3/CIM5 below -67 dBc, and adjacent-channel leakage ratio of -61 dBc with LTE20 carrier. The circuit consumes 150 mW from 0.9-/1.5-V supplies at +3 dBm output power.

Original languageEnglish
Pages (from-to)3434-3445
Number of pages12
JournalIEEE Journal of Solid-State Circuits
Volume52
Issue number12
DOIs
Publication statusPublished - 21 Nov 2017
MoE publication typeA1 Journal article-refereed

Keywords

  • All-digital transmitter (TX)
  • Attenuation
  • Baseband
  • delta-sigma
  • LTE
  • mismatch-shaping
  • Modulation
  • Noise shaping
  • Quantization (signal)
  • Radio frequency
  • receive band (RX-band) noise
  • RF-DAC
  • Standards

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