Highly Tunable Low-impedance Capacitive Micromechanical Resonators, Oscillators, And Processes Relating Thereto
Ho, Gavin Kar-fai
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Disclosed are capacitive micromechanical resonators optimized for high Q, low motional impedance, and large tuning range. Exemplary resonators were fabricated using a HARPSS-on-SOI process, and demonstrated quality factors up to 119000 in vacuum. For resonators operating between 3 MHz and 30 MHz, the lowest extracted impedance is 218 k? and the largest electrostatic tuning coefficient is ?240 ppm/V2. The disclosed designs are applicable up to at least 200 MHz operation. An oscillator interface circuit comprising of a trans-impedance amplifier and an automatic bias generator providing a temperature-compensating bias voltage is also disclosed. Experiments show temperature drift reduction from 2800 ppm to 39 ppm over a 100� C. range. Process compensation (DFM) of micromechanical resonators, resonators having mass loading elements that allow generation of closely spaced frequencies, and coupled systems comprising of the resonators are also described.
- Georgia Tech Patents