A 100-nW 9.1-ENOB 20-kS/s SAR ADC for portable pulse oximeter

Hokyu Lee, Sejin Park, Chaegang Lim, Chulwoo Kim

    Research output: Contribution to journalArticlepeer-review

    30 Citations (Scopus)

    Abstract

    This brief presents an energy-efficient 10-bit accuracy with 20-kS/s successive approximation register analog-to-digital converter for portable pulse oximeter. A data-dependent capacitor reset (DDCR) switching scheme for the capacitive digital-to-analog converter (CDAC) to reduce the average switching energy and the number of unit capacitors is proposed and implemented. Compared with the conventional capacitor switching scheme for CDACs, the proposed DDCR switching scheme reduces the average switching energy and the total number of unit capacitors by 97% and 75%, respectively. We achieved a signal-to-noise-and-distortion ratio of 56.5 dB and a spurious-free dynamic range of 64.7 dBc at the Nyquist input frequency. The measured peak differential and integral nonlinearities are 0.44 and 0.58 least significant bit, respectively. The figure of merit is 9.1 fJ/conversion-step. The prototype, fabricated in the 0.11-μm CMOS process, occupies 0.033 mm2.

    Original languageEnglish
    Article number7001238
    Pages (from-to)357-361
    Number of pages5
    JournalIEEE Transactions on Circuits and Systems II: Express Briefs
    Volume62
    Issue number4
    DOIs
    Publication statusPublished - 2015 Apr 1

    Bibliographical note

    Publisher Copyright:
    © 2004-2012 IEEE.

    Keywords

    • Pulse oximeter
    • U-Healthcare
    • analog-to-digital converter
    • energy efficient
    • low-power
    • successive approximation register

    ASJC Scopus subject areas

    • Electrical and Electronic Engineering

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