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A power-efficient capacitive read-out circuit with parasitic-cancellation for MEMS Cochlea sensors

A power-efficient capacitive read-out circuit with parasitic-cancellation for MEMS Cochlea sensors
A power-efficient capacitive read-out circuit with parasitic-cancellation for MEMS Cochlea sensors

This paper proposes a solution for signal read-out in the MEMS cochlea sensors that have very small sensing capacitance and do not have differential sensing structures. The key challenge in such sensors is the significant signal degradation caused by the parasitic capacitance at the MEMS-CMOS interface. Therefore, a novel capacitive read-out circuit with parasitic-cancellation mechanism is developed; the equivalent input capacitance of the circuit is negative and can be adjusted to cancel the parasitic capacitance. Chip results prove that the use of parasitic-cancellation is able to increase the sensor sensitivity by 35 dB without consuming any extra power. In general, the circuit follows a low-degradation low-amplification approach which is more power-efficient than the traditional high-degradation high-amplification approach; it employs parasitic-cancellation to reduce the signal degradation and therefore a lower gain is required in the amplification stage. Besides, the chopper-stabilization technique is employed to effectively reduce the low-frequency circuit noise and DC offsets. As a result of these design considerations, the prototype chip demonstrates the capability of converting a 7.5 fF capacitance change of a 1-Volt-biased 0.5 pF capacitive sensor pair into a 0.745 V signal-conditioned output at the cost of only 165.2 μW power consumption.

Capacitive read-out, chopper-stabilization, low capacitance measurement, MEMS cochlea, parasitic-cancellation, sensor interface
1932-4545
25-37
Wang, Shiwei
97433cb6-7752-4c68-89f8-933f233d8642
Koickal, Thomas Jacob
ca8588e6-32a5-4d70-8068-0a17178a5cc8
Hamilton, Alister
248e45ad-b658-4af3-9bdb-b09caeae9238
Mastropaolo, Enrico
b6991cbf-7da3-4a8b-9a4d-cddab941727b
Cheung, Rebecca
6e95e1b3-1506-43d3-a1d1-578ddbcb7708
Abel, Andrew
b0382ebf-6ff8-46b2-b3d5-8abb5108cdb2
Smith, Leslie S.
cd83099c-eee3-461d-8989-df88d91dfc3d
Wang, Lei
4c1b7e89-81dd-48f3-8ac9-e6a5ca2f495c
Wang, Shiwei
97433cb6-7752-4c68-89f8-933f233d8642
Koickal, Thomas Jacob
ca8588e6-32a5-4d70-8068-0a17178a5cc8
Hamilton, Alister
248e45ad-b658-4af3-9bdb-b09caeae9238
Mastropaolo, Enrico
b6991cbf-7da3-4a8b-9a4d-cddab941727b
Cheung, Rebecca
6e95e1b3-1506-43d3-a1d1-578ddbcb7708
Abel, Andrew
b0382ebf-6ff8-46b2-b3d5-8abb5108cdb2
Smith, Leslie S.
cd83099c-eee3-461d-8989-df88d91dfc3d
Wang, Lei
4c1b7e89-81dd-48f3-8ac9-e6a5ca2f495c

Wang, Shiwei, Koickal, Thomas Jacob, Hamilton, Alister, Mastropaolo, Enrico, Cheung, Rebecca, Abel, Andrew, Smith, Leslie S. and Wang, Lei (2015) A power-efficient capacitive read-out circuit with parasitic-cancellation for MEMS Cochlea sensors. IEEE Transactions on Biomedical Circuits and Systems, 10 (1), 25-37, [7069184]. (doi:10.1109/TBCAS.2015.2403251).

Record type: Article

Abstract

This paper proposes a solution for signal read-out in the MEMS cochlea sensors that have very small sensing capacitance and do not have differential sensing structures. The key challenge in such sensors is the significant signal degradation caused by the parasitic capacitance at the MEMS-CMOS interface. Therefore, a novel capacitive read-out circuit with parasitic-cancellation mechanism is developed; the equivalent input capacitance of the circuit is negative and can be adjusted to cancel the parasitic capacitance. Chip results prove that the use of parasitic-cancellation is able to increase the sensor sensitivity by 35 dB without consuming any extra power. In general, the circuit follows a low-degradation low-amplification approach which is more power-efficient than the traditional high-degradation high-amplification approach; it employs parasitic-cancellation to reduce the signal degradation and therefore a lower gain is required in the amplification stage. Besides, the chopper-stabilization technique is employed to effectively reduce the low-frequency circuit noise and DC offsets. As a result of these design considerations, the prototype chip demonstrates the capability of converting a 7.5 fF capacitance change of a 1-Volt-biased 0.5 pF capacitive sensor pair into a 0.745 V signal-conditioned output at the cost of only 165.2 μW power consumption.

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More information

Published date: 26 March 2015
Keywords: Capacitive read-out, chopper-stabilization, low capacitance measurement, MEMS cochlea, parasitic-cancellation, sensor interface

Identifiers

Local EPrints ID: 446128
URI: http://eprints.soton.ac.uk/id/eprint/446128
ISSN: 1932-4545
PURE UUID: fd6b5460-871e-4199-b640-d8a0ecf40e75
ORCID for Shiwei Wang: ORCID iD orcid.org/0000-0002-5450-2108

Catalogue record

Date deposited: 21 Jan 2021 17:34
Last modified: 04 Sep 2021 02:06

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Contributors

Author: Shiwei Wang ORCID iD
Author: Thomas Jacob Koickal
Author: Alister Hamilton
Author: Enrico Mastropaolo
Author: Rebecca Cheung
Author: Andrew Abel
Author: Leslie S. Smith
Author: Lei Wang

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