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Design and Characterization Methodology for Efficient Wide Range Tunable MEMS Filters
Published on: February 4, 2018
High-frequency SAW filters based on diamond films
1Organization for Academic–Industrial Collaboration and Intellectual Property, Chiba University, Japan. s_fujii@faculty.chiba-u.jp
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
|December 11, 2012
Summary
We developed a diamond substrate surface acoustic wave (SAW) resonator operating above 3 GHz. This device achieves high Q values and stable frequency across temperatures, showing potential for SHF-band filters.
Area of Science:
- Materials Science
- Electrical Engineering
- Acoustics
Background:
- Surface Acoustic Wave (SAW) devices are crucial for signal processing, but high-frequency operation and temperature stability remain challenges.
- Diamond substrates offer high acoustic velocity, beneficial for high-frequency SAW applications.
- Optimizing layered structures is key to enhancing SAW device performance, including Q value and temperature coefficient of frequency (TCF).
Purpose of the Study:
- To develop a diamond SAW resonator operating at frequencies over 3 GHz with enhanced performance.
- To investigate the feasibility of a SiO(2)/interdigital transducer (IDT)/AlN/diamond structure for high-frequency SAW devices.
- To achieve a zero TCF and low insertion loss for SAW resonators and filters.
Main Methods:
- Theoretical and experimental studies of SAW characteristics in various SiO(2)/IDT/AlN/diamond layered structures.
- Fabrication and characterization of one-port and two-port SAW resonators.
- Design and simulation of a 5-GHz band-stop SAW filter.
Main Results:
- A SiO(2)/IDT/AlN/diamond structure enabled a thicker IDT metal layer, reducing series resistance and insertion loss.
- Sezawa-mode SAW exhibited a phase velocity of 11,150 m/s and electromechanical coupling coefficient of 0.5%, with a zero TCF at 25°C.
- One-port resonators achieved a high Q of 660 at 5.4 GHz, and a two-port resonator showed low insertion loss (8 dB). A 5-GHz band-stop filter demonstrated a 30-MHz stopband with 0.76 dB passband insertion loss.
Conclusions:
- The developed SiO(2)/IDT/AlN/diamond structure is highly suitable for high-frequency (over 3 GHz) SAW devices.
- The fabricated SAW resonators and filters exhibit excellent performance, including high Q, low insertion loss, and good temperature stability.
- This technology shows significant potential for SHF-band filter applications.
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