A readout circuit for tunnel magnetoresistive sensors employing an ultra-low-noise current source

Mohamed, A., Heidari, H. and Anders, J. (2021) A readout circuit for tunnel magnetoresistive sensors employing an ultra-low-noise current source. In: ESSCIRC 2021 - IEEE 47th European Solid State Circuits Conference (ESSCIRC), 13-22 Sep 2021, pp. 331-334. ISBN 9781665437516 (doi: 10.1109/ESSCIRC53450.2021.9567752)

Abstract

We present a tunneling magnetoresistive (TMR) sensing microsystem consisting of a low flicker noise TMR sensor and a custom integrated readout frontend. The proposed sensor readout circuit introduces a novel ultra-low-noise current biasing scheme for the TMR sensor, which achieves a very low current noise floor of 2.2 pA√Hz for a 1 mA biasing current. The TMR output voltage is processed by a differential readout scheme to improve the baseline-to-signal ratio. The microsystem also features an on-chip 10-bit current DAC that allows compensating for the large process variations in the TMR base resistance value. The readout chip is manufactured in a 180 nm SOI CMOS technology and heterogeneously integrated with the TMR sensor. The readout chain provides a thermal noise floor of 4nV/√Hz, while, together with the biasing scheme, consuming a total power of 38 mW. The complete sensor system consisting of the TMR and the readout circuit provides a state-of-the-art magnetic field noise floor of 120 pT/√Hz.

• Item Type: Conference Proceedings
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Heidari, Professor Hadi
• Authors: Mohamed, A., Heidari, H., and Anders, J.
• College/School: College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
• ISBN: 9781665437516
• Published Online: 26 October 2021
• Copyright Holders: Copyright © 2021 IEEE
• Publisher Policy: Reproduced in accordance with the publisher copyright policy

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