An 8-bit single-ended ultra-low-power SAR ADC with a novel DAC switching method and a counter-based digital control circuitry

Weibo Hu, Yen Ting Liu, Tam Nguyen, Donald Y.C. Lie, Brian P. Ginsburg

Research output: Contribution to journalArticlepeer-review

44 Scopus citations

Abstract

This paper proposes a design of ultra-low-power successive approximation register (SAR) analog-to-digital converters (ADC) specially optimized for very low frequency biosensor applications. Two new techniques are introduced: 1) a novel digital-to-analog converter (DAC) switching method suitable for single-ended SAR ADCs; and 2) a counter-based digital control circuitry. The DAC switching method uses VR/2 as an only reference voltage to digitize the input signals within [0, VR], and reduces the power consumption in the DAC during digitizing by 87.5% versus the traditional one. The counter-based controller can reduce power consumption in the digital circuitry by 30%. Two prototype 8-bit SAR ADCs are designed, one in a TI 0.35-μm Bipolar-CMOS-DMOS (BCD) process and the other in a TSMC 0.18-μm CMOS process. The 0.35-μm ADC consumes 101 nW, and achieves a signal to noise and distortion ratio (SNDR) of 48.2 dB and a figure of merit (FOM) of 227 fJ/conversion-step at 2 kS/s. The 0.18-μm ADC can achieve a SNDR of 46.3 dB with only 27 nW and a FOM of 79.9 fJ/conversion-step at 2 kS/s.

Original languageEnglish
Article number6547197
Pages (from-to)1726-1739
Number of pages14
JournalIEEE Transactions on Circuits and Systems I: Regular Papers
Volume60
Issue number7
DOIs
StatePublished - 2013

Keywords

  • Analog-to-digital converter (ADC)
  • digital-to-analog converter (DAC)
  • successive approximation register (SAR) ADC
  • ultra-low-power sensor

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