Temperature-Compensated Self-Sensing Diamond Ring Resonator

The use of CVD diamond structural material together with a new semi-empirical compensating voltage function has permitted gap-based electrical stiffness temperature compensation [1] to reduce the resonance frequency excursion of an 87-MHz radial-mode ring resonator to only 68.8 ppb (±34 ppb) over <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$25-105^{\circ}\mathrm{C}$</tex>. This represents a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$130\times$</tex> improvement over the previous best applied to a compensated polysilicon device and a remarkable <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2, 165\times$</tex> enhancement over the -149 ppm of the uncompensated diamond device. This performance now approaches that of oven-controlled devices sans their power consumption. Key to achieving this is the use of polydiamond structural material over a silicon substrate which not only reduces the starting uncompensated frequency excursion vs polysilicon but also provides thermal expansion coefficient differences that enable gap-based temperature sensing and frequency correction via a more accurate compensating voltage function.