A near-infrared heart rate measurement IC with very low cutoff frequency using current steering technique

Alex Wong, Kong Pang Pun, Yuan Ting Zhang, Kevin Hung

Research output: Contribution to journalArticlepeer-review

54 Citations (Scopus)

Abstract

A near-infrared heart-rate measurement IC that processes the photoplethysmographic signal was designed using a 0.35-μm CMOS technology. The IC consists of a current-to-voltage (I-V) converter, a buffer, a sample-and-hold circuit, a second-order continuous-time low-pass filter (CT-LPF), a comparator, and a timing circuit that is used to pulse the external light-emitting diode with a very low duty cycle to reduce its power consumption. The current steering technique is employed in the design of the CT-LPF to meet the requirement for very low cutoff frequency. The circuit operates from a 3-V lithium battery, occupies a core area of 0.46 mm2 and has a power consumption of 4.5 mW. The measurement results corroborate with simulation results and show that the CT-LPF can achieve a cutoff frequency of as low as 0.25 Hz. This demonstrates the feasibility of current steering technique in the design of filter for low-frequency application.

Original languageEnglish
Pages (from-to)2642-2647
Number of pages6
JournalIEEE Transactions on Circuits and Systems I: Regular Papers
Volume52
Issue number12
DOIs
Publication statusPublished - Dec 2005
Externally publishedYes

Keywords

  • Biomedical sensor
  • Biomedical signal acquisition
  • Current-steering
  • Heart-rate measurement
  • Near-infrared (NIR) sensor
  • Photoplethysmogram (PPG)
  • Very low cutoff frequency filter

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