Analysis and Design of Coupled Inductive Bridges for Magnetic Sensing Applications

Matan Gal-Katziri, Ali Hajimiri

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

This paper presents the analysis and design of a novel magnetic sensor. We study the underlying physics of inductance shift sensors as a special case of the broader family of magnetic energy deviation sensors. The result is a quantitative definition of performance metrics with all assumptions and approximations explicitly stated. This analysis is then used to design a modified ac Wheatstone bridge that uses two inductor-pairs in a cross-coupled configuration, to half its size and double its transducer gain while maintaining a fully differential structure with a matched frequency response. A proof-of-concept sensor was fabricated with peripheral circuitry in a 65-nm bulk CMOS process to operate between 770 and 1450 MHz with an effective sensing area of 200 \mu \text{m}\,\,\times 200 \mu \text{m}. The new bridge sensor is fully characterized at a frequency of 770 MHz and demonstrates a reliable and continuous detection of 4.5- \mu \text{m} iron-oxide magnetic beads over time periods longer than 30 min, appreciably longer than previously reported works.

Original languageEnglish
Article number8704923
Pages (from-to)1883-1894
Number of pages12
JournalIEEE Journal of Solid-State Circuits
Volume54
Issue number7
DOIs
StatePublished - 1 Jul 2019
Externally publishedYes

Keywords

  • Biosensors
  • CMOS integrated circuits
  • bridge circuits
  • inductive transducers
  • magnetic sensors

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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