A System Based on Capacitive Interfacing of CMOS With Post-Processed Thin-Film MEMS Resonators Employing Synchronous Readout for Parasitic Nulling

Liechao Huang, Warren Rieutort-Louis, Alexandra Gualdino, Laura Teagno, Yingzhe Hu, João Mouro, Josue Sanz-Robinson, James C. Sturm, Sigurd Wagner, Virginia Chu, João Pedro Conde, Naveen Verma

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

Thin-film MEMS resonators fabricated at low temperatures can be processed on CMOS ICs, forming high-sensitivity transducers within complete sensing systems. A key focus for the MEMS devices is increasing the resonant frequency, enabling, among other benefits, operation at atmospheric pressure. However, at increased frequencies, parasitics associated with both the MEMS-CMOS interfaces and the MEMS device itself can severely degrade the detectability of the resonant peak. This work attempts to overcome these parasitics while providing isolation of the CMOS IC from potentially damaging sensing environments. To achieve this, an interfacing approach is proposed based on capacitive coupling across the CMOS IC passivation, and a detection approach is proposed based on synchronous readout. Results are presented from a prototype system, integrating a custom CMOS IC with MEMS bridge resonators. With the MEMS resonators fabricated in-house at 175°C on a separate substrate, readout results with multiple different resonators are obtained. In all cases, the IC enables detection with >20 dB SNR of resonant peaks that are only weakly detectable or undetectable directly using a vector-network analyzer (VNA).

Original languageEnglish (US)
Article number7001679
Pages (from-to)1002-1015
Number of pages14
JournalIEEE Journal of Solid-State Circuits
Volume50
Issue number4
DOIs
StatePublished - Apr 1 2015

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering

Keywords

  • ASIC
  • Amorphous silicon
  • MEMS
  • non-contact interface
  • resonator sensor
  • synchronous readout
  • thin-film technology

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    Huang, L., Rieutort-Louis, W., Gualdino, A., Teagno, L., Hu, Y., Mouro, J., Sanz-Robinson, J., Sturm, J. C., Wagner, S., Chu, V., Conde, J. P., & Verma, N. (2015). A System Based on Capacitive Interfacing of CMOS With Post-Processed Thin-Film MEMS Resonators Employing Synchronous Readout for Parasitic Nulling. IEEE Journal of Solid-State Circuits, 50(4), 1002-1015. [7001679]. https://doi.org/10.1109/JSSC.2014.2380440