An Integrated Analog Lock-In Amplifier using a Passive 3-Path Band-Pass Filter for a Fluxgate Sensor Readout Circuit

Research output: Chapter in Book/Report/Conference proceedingConference paperpeer-review

Abstract

Lock-in amplifiers are versatile measuring instruments for extracting a narrow-bandwidth signal with a known carrier from noisy environments. The lock-in amplifier presented here has therefore been designed to provide an efficient readout of the second harmonic of fluxgate sensors. However, existing analog lock-in amplifiers use band-pass filters with increased component count or even omit them altogether. Therefore, the proposed lock-in amplifier takes advantage of the N-path filter principle to minimize chip area and power consumption. The lock-in amplifier consists of a low noise programmable gain preamplifier and a passive band-pass filter that uses a switched-capacitor topology. In this way, the filter achieves a high level of power efficiency and reconfigurability in terms of a tunable center frequency and bandwidth. The complete circuit is integrated on chip using a 180nm CMOS technology and occupies a total area of only 0.42mm^2. Moreover, the lock-in amplifier achieves a simulated input-referred noise voltage of 5.5nV /\sqrtHz at 10kHz while consuming less than 1mA under a 1.8V supply voltage.

Original languageEnglish
Title of host publication2023 21st IEEE Interregional NEWCAS Conference (NEWCAS)
Number of pages4
ISBN (Electronic)9798350300246
DOIs
Publication statusPublished - 2023
Event21st IEEE Interregional NEWCAS Conference: NEWCAS 2023 - Edinburgh, United Kingdom
Duration: 26 Jun 202328 Jun 2023

Conference

Conference21st IEEE Interregional NEWCAS Conference
Abbreviated titleNEWCAS 2023
Country/TerritoryUnited Kingdom
CityEdinburgh
Period26/06/2328/06/23

Keywords

  • Analog lock-in amplifier
  • CMOS integrated circuit
  • fluxgate magnetometer
  • n-path filter
  • sensor interface

ASJC Scopus subject areas

  • Safety, Risk, Reliability and Quality
  • Instrumentation
  • Electrical and Electronic Engineering
  • Hardware and Architecture
  • Computer Networks and Communications
  • Modelling and Simulation

Cite this