A silicon-based closed-loop 256-pixel near-field capacitive sensing array with 3-ppm sensitivity and selectable frequency shift gain

Jia Zhou*, Chia Jen Liang, Christopher Chen, Jieqiong Du, Rulin Huang, Richard Al Hadi, James C.M. Hwang, Mau Chung Frank Chang

*Corresponding author for this work

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

Abstract

This paper presents a two-dimensional capacitive sensor circuit implemented in 28-nm silicon technology for material characterization. The circuit is based on a 4.5-GHz quadrature oscillator with a single inductor and distributed capacitor array with 12.6-um pitch. The 16×16 sensor array is designed with minimal signal energy loss to enable scalable designs. The quadrature oscillator is embedded in a trans-linear loop for frequency shift amplification up to 36 times with an acquisition bandwidth of 2.4 MHz. The readout time for single pixel drops below the limit set by the quantization noise floor and reaches near optimal window, while the sensor maintains a sensitivity of 3 ppm. A mixer is used to down-convert the high-frequency component to an intermediate frequency. A digital core is used to acquire and process the data.

Original languageEnglish
Title of host publicationIMS 2020 - 2020 IEEE/MTT-S International Microwave Symposium
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages464-467
Number of pages4
ISBN (Electronic)9781728168159
DOIs
StatePublished - Aug 2020
Event2020 IEEE/MTT-S International Microwave Symposium, IMS 2020 - Virtual, Los Angeles, United States
Duration: 4 Aug 20206 Aug 2020

Publication series

NameIEEE MTT-S International Microwave Symposium Digest
Volume2020-August
ISSN (Print)0149-645X

Conference

Conference2020 IEEE/MTT-S International Microwave Symposium, IMS 2020
CountryUnited States
CityVirtual, Los Angeles
Period4/08/206/08/20

Keywords

  • Capacitive sensor
  • Imaging array
  • Near-field detector
  • Silicon

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