Small Foot-print, High Q, SAW Resonator

Technology #17931

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Professor Dana Weinstein
Department of Electrical Engineering and Computer Science, MIT
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Siping Wang
Department of Electrical Engineering and Computer Science, MIT
Laura Popa
Department of Physics, MIT
Managed By
Christopher Noble
MIT Technology Licensing Officer - Clean and Renewable Energy
Patent Protection

Tapered Photonic Crystal Saw Resonator

Provisional Patent Application Filed
Tapered Phononic Crystal Saw Resonator in GaN
28th IEEE International Conference on Micro Electro Mechanical Systems (MEMS), pp.1028,1031, 18-22 Jan. 2015


MEMS resonators for:

  • wireless communication,
  • telecommunication,
  • radio-frequency front-end components,
  • sensors,
  • microprocessor technology,
  • clocking and transceiver circuitry.

Problems Addressed

The fabrication of a surface acoustic wave (SAW) resonator does not require the release step that is common in most MEMS devices. This results in higher yield with a simple design and packaging of the resonator. However, conventional SAW resonators are large , as a result of using periodic metal gratings as reflectors to confine the acoustic energy.


This technology uses a Phononic Crystal (PnC) with deep etched periodic holes to form the SAW reflector. The dimensions of the periodic holes are tapered to generate a gradual change in the acoustic impedance, which reduces the scattering of the acoustic wave into the substrate. For example, twenty layers of periodic holes are sufficient for an effective energy confinement compared to hundreds of metal gratings required in conventional SAW resonators. The use of tapered holes reduces the footprint by more than two orders of magnitude relative to the conventional metal grating reflectors while maintaining a high Q factor. These devices can be seamlessly integrated with Gallium Nitride (GaN) based monolithic microwave integrated circuits (MMIC).


  • Reduced footprint
  • High Q factor
  • High manufacturing yield
  • Simple design and packaging
  • High piezoelectric coefficient
  • Capable of seamless integration with HEMTs and MMICs