A >1W 2.2GHz switched-capacitor digital power amplifier with wideband mixed-domain multi-tap FIR filtering of OOB noise floor

Ritesh Bhat, Jin Zhou, Harish Krishnaswamy

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Digital power amplifiers and transmitters have drawn significant interest in the recent past due to their reconfigurability, compatibility with CMOS technology scaling and DSP, and potential for automated design synthesis [1-5]. While significant progress has been made in achieving moderate output power levels in CMOS, wideband modulation, and high efficiency under back-off, out-of-band emissions remain an unsolved problem. The elimination of the analog reconstruction filter that follows the DAC in a conventional analog transmitter implies that broadband DAC quantization noise appears at the output of the transmitter unfiltered. Quantization noise can be suppressed by increasing resolution and/or sampling rate, but to meet the challenging -150 to -160dBc/Hz out-of-band (OOB and specifically RX-band) noise requirement of FDD with conventional duplexers, nearly 12b at 0.5GS/s is required. Such a high effective number of bits (ENOB) is extremely challenging in digital PAs given their strong output nonlinearity. Consequently, while low-power modulators are able to approach -150dBc/Hz RX-band noise floor and below [6], state-of-the-art digital transmitters achieve -130 to -135dBc/Hz RX-band noise, nearly 20dB or 100× away [2-4]. Embedding mixed-domain FIR filtering into digital transmitters to create notches in the RX band has been proposed [4,7], but, while successful in low-power modulators [7], nonlinearity significantly limits notch depth to <10dB in digital PAs [4]. Further, notch bandwidth (BW) is far less than 20MHz, the typical LTE BW, in the simple two-tap FIR structures that have been explored [4].

Original languageEnglish (US)
Title of host publication2017 IEEE International Solid-State Circuits Conference, ISSCC 2017
EditorsLaura C. Fujino
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages234-235
Number of pages2
ISBN (Electronic)9781509037575
DOIs
StatePublished - Mar 2 2017
Externally publishedYes
Event64th IEEE International Solid-State Circuits Conference, ISSCC 2017 - San Francisco, United States
Duration: Feb 5 2017Feb 9 2017

Publication series

NameDigest of Technical Papers - IEEE International Solid-State Circuits Conference
Volume60
ISSN (Print)0193-6530

Other

Other64th IEEE International Solid-State Circuits Conference, ISSCC 2017
CountryUnited States
CitySan Francisco
Period2/5/172/9/17

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ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

Cite this

Bhat, R., Zhou, J., & Krishnaswamy, H. (2017). A >1W 2.2GHz switched-capacitor digital power amplifier with wideband mixed-domain multi-tap FIR filtering of OOB noise floor. In L. C. Fujino (Ed.), 2017 IEEE International Solid-State Circuits Conference, ISSCC 2017 (pp. 234-235). [7870347] (Digest of Technical Papers - IEEE International Solid-State Circuits Conference; Vol. 60). Institute of Electrical and Electronics Engineers Inc.. https://doi.org/10.1109/ISSCC.2017.7870347