A Fully Passive RF Front-end with 13 dB Gain Exploiting Implicit Capacitive Stacking in a Bottom-plate N-path Filter/Mixer

Vijaya Kumar Purushothaman, Eric A.M. Klumperink, Berta Trullas Clavere, Bram Nauta

Research output: Contribution to journalArticleAcademicpeer-review

53 Citations (Scopus)
763 Downloads (Pure)

Abstract

A low-power interferer-robust mixer-first receiver front end that uses a novel capacitive stacking technique in a bottom-plate N-path filter/mixer is proposed. Capacitive stacking is achieved by reading out the voltage from the bottom plate of N-path capacitors instead of their top plate, which provides a 2\times voltage gain after downconversion. A step-up transformer is used to improve the out-of-band (OOB) linearity performance of small switches in the N-path mixer, thereby reducing the power consumption of switch drivers. This article explains the concept of implicit capacitive stacking and analyzes its transfer characteristics. A prototype chip, fabricated in 22-nm fully depleted silicon on insulator (FDSOI) technology, achieves a voltage gain of 13 dB and OOB IIP3/IIP2 of +25/+66 dBm with 5-dB noise figure while consuming only 600 \mu \text{W} of power at f_{\mathrm{ LO}}=1 GHz. Thanks to the transformer, the prototype can operate in the input frequency range of 0.6-1.2 GHz with more than 10-dB voltage gain and 5-9-dB noise figure. Thus, it opens up the possibility of low-power software-defined radios.

Original languageEnglish
Article number8944060
Pages (from-to)1139-1150
Number of pages12
JournalIEEE journal of solid-state circuits
Volume55
Issue number5
Early online date27 Dec 2019
DOIs
Publication statusPublished - 1 May 2020

Keywords

  • Bottom-plate mixing
  • CMOS
  • Internet-of-Things (IoTs)
  • N-path filter
  • RF front end
  • capacitive stacking
  • high linearity
  • interference-robust
  • low power
  • mixer-first receiver
  • passive mixer
  • transformer

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