A MEMS Coriolis-Based Mass-Flow-to-Digital Converter for Low Flow Rate Sensing

Arthur Campos de Oliveira, Sining Pan, Remco J. Wiegerink, Kofi A.A. Makinwa

Research output: Contribution to journalArticleScientificpeer-review

Abstract

This article presents a microelectromechanical system (MEMS) Coriolis-based mass-flow-to-digital converter (Φ DC) that can be used with both liquids and gases. It consists of a micromachined Coriolis mass flow sensor and a CMOS interface circuit that drives it into oscillation and digitizes the resulting mass flow information. A phase-locked loop (PLL) drives the sensor at its resonance frequency (fD), while a low 1/f noise switched-capacitor (SC) proportional-integral (PI) controller maintains a constant drive amplitude. Mass flow through the sensor causes Coriolis-force-induced displacements, which are detected by co-integrated sense capacitors. In-phase (I) and quadrature (Q) components of these displacements are then digitized by two continuous-time delta-sigma modulators (CT- ΔΣ Ms) with finite impulse response (FIR)-DACs and passive mixers. Their outputs are used to accurately estimate and cancel sense path delay, thus improving sensor stability. To ensure constant sensitivity over a wide range of fluid densities, a background sensitivity tuning (BST) scheme adjusts the sense capacitors' bias voltage as a function of fD, which is a good proxy for fluid density. Implemented in a standard 0.18- μm CMOS technology, the interface circuit consumes 13 mW from a 1.8-V supply. The proposed MEMS Coriolis Φ DC achieves a state-of-the-art noise floor of 80 μg/h/√ Hz and a zero stability (ZS) of ±0.31 mg/h, which is at par with MEMS thermal flow sensors.

Original languageEnglish
Pages (from-to)3681-3692
Number of pages12
JournalIEEE Journal of Solid-State Circuits
Volume57
Issue number12
DOIs
Publication statusPublished - 2022

Bibliographical note

Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care
Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Keywords

  • Capacitive interface
  • CMOS readout interface
  • Coriolis mass flow sensor
  • delta–sigma modulator (<inline-formula xmlns:ali="http://www.niso.org/schemas/ali/1.0/" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <tex-math notation="LaTeX">$\Delta\Sigma$</tex-math> </inline-formula>M)
  • flow rate
  • flowmeter
  • demodulator
  • low noise
  • microelectromechanical systems (MEMS)
  • microfluidics

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