An ultra low energy 12-bit rate-resolution scalable SAR ADC for wireless sensor nodes

Naveen Verma, Anantha P. Chandrakasan

Research output: Contribution to journalArticlepeer-review

302 Scopus citations


A resolution-rate scalable ADC for micro-sensor networks is described. Based on the successive approximation register (SAR) architecture, this ADC has two resolution modes: 12 bit and 8 bit, and its sampling rate is scalable, at a constant figure-of-merit, from 0-100 kS/s and 0-200 kS/s, respectively. At the highest performance point (i.e., 12 bit, 100 kS/s), the entire ADC (including digital, analog, and reference power) consumes 25 μW from a 1-V supply. The ADC's CMRR is enhanced by common-mode independent sampling and passive auto-zero reference generation. The efficiency of the comparator is improved by an analog offset calibrating latch, and the preamplifier settling time is relaxed by selftiming the bit-decisions. Prototyped in a 0.18-μxm, 5M2P CMOS process, the ADC, at 12 bit, 100 kS/s, achieves a Nyquist SNDR of 65 dB (10.55 ENOB) and an SFDR of 71 dB. Its INL and DNL are 0.68 LSB and 0.66 LSB, respectively.

Original languageEnglish (US)
Pages (from-to)1196-1205
Number of pages10
JournalIEEE Journal of Solid-State Circuits
Issue number6
StatePublished - Jun 2007
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering


  • ADC
  • Analog-to-digital conversion
  • CMOS analog integrated circuits
  • Circuit noise
  • Low-power electronics
  • Offset compensation
  • Scaleable
  • Successive approximation register


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