Sensors (Jun 2024)

A Surface Acoustic Wave-Based PM 1.0 Fine Dust Detection System Using Full Digital Time-Interleaved Counters

  • Chang-Hyeon Kim,
  • Ki-Hoon Yang,
  • Yeon-Seob Song,
  • Sang-Sun Yoo,
  • Younggun Pu,
  • Il-Hwan Kim,
  • Seok-Whan Chung,
  • Kwang-Wook Choi,
  • Jun-Eun Park,
  • Kang-Yoon Lee

DOI
https://doi.org/10.3390/s24134149
Journal volume & issue
Vol. 24, no. 13
p. 4149

Abstract

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This paper proposed a fine dust detection system using time-interleaved counters in which surface acoustic wave (SAW) sensors changed the resonance point characteristic. When fine dust was applied to the SAW sensor, the resonance point decreased. The SAW oscillator made of the SAW sensor and radio frequency (RF) amplifier generated an oscillation frequency that was the same as the resonance frequency. The oscillation frequency was transferred to digital data by a 20-bit asynchronous counter. This system has two channels: a sensing channel and a reference channel. Each channel has a SAW oscillator and a 20-bit asynchronous counter. The difference of the two channel counter results is the frequency difference. Through this, it is possible to know whether fine dust adheres to the SAW sensor. The proposed circuit achieved 0.95 ppm frequency resolution when it was operated at a frequency of 460 MHz. This circuit was implemented in a TSMC 130 nm CMOS process.

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