Capacitively transduced vibrating micromechanical resonators have recently been demonstrated with resonant frequencies in the GHz range with Q’s larger than 11,000, making them very attractive as on-chip frequency control elements for oscillators and filters in wireless communications. Although solutions now exist to many of the issues that once hindered deployment of these devices in RF front ends including aging and temperature stability, the need for high bias voltages to reduce impedances, especially in the VHF and UHF ranges, still remains a troublesome drawback of this technology.
University of Michigan researchers have developed micromechanical structures where impedance is lowered while avoiding the need to increase the area of a capacitively transduced micromechanical resonator by raising the permittivity of the dielectric in its capacitive gap, thereby raising the efficiency of its transducer. These advantages with the right dielectric material now allows capacitively-transduced resonators to match to the 50-377.OMEGA. impedances expected by off-chip components (e.g., antennas) in many wireless applications without the need for high voltages. In addition, as described in this invention, the use of filled-dielectric transducer gaps actually enhances the yield and reliability of capacitively transduced devices, since it removes problems generated by air gaps.
Applications and Advantages
- Sensors for wireless applications
- Lower motional resistance
- Saves costs
- Better Stabilization against shock and-nl-microphonics
- Good fabrication yield