Logan Sorenson

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Nonlinearity of a silicon resonator can lead to improved phase-noise performance in an oscillator when the phase shift of the sustaining amplifier forces the operating point to a steeper phase-frequency slope. As a result, phase modulation on the oscillator frequency is minimized because the resonator behaves as a high-order phase filter. The effect of the(More)
This paper shows improved phase-noise performance of MEMS oscillators when the sustaining amplifier operates a lateral bulk acoustic wave AlN-on-Si resonator in the nonlinear regime. An empirical exponential-series-based model that closely describes the phase noise in nonlinearity is presented, reflecting the increased resonator filter order and the reduced(More)
The effect of thickness anisotropy on the degenerate elliptical resonance modes of micro-hemispherical shell resonators (μHSRs) created using the thermal oxidation process is investigated. This anisotropy arises from the variation in wet thermal oxide growth according to the exposed crystal planes of the single-crystal-silicon hemispherical mold used to(More)
This paper presents a new empirical exponential-series-based model that describes the measured phase-noise (PN) of a nonlinear piezoelectric MEMS oscillator. Since the order of terms in the Leeson’s model can only provide at maximum -30 dB/dec slope, a model with higher order terms is proposed to determine an effective resonator quality factor (Qeff) and(More)
Fundamental characteristics of MEMS resonators such as acoustic velocity and energy dissipation may have strong temperature and process dependencies that must be carefully compensated in applications requiring high degrees of stability and accuracy. This paper presents an overview of compensation, tuning, and trimming techniques for MEMS resonators. The use(More)
This paper reports on electrical characterization of ALD-coated thermally-grown silicon dioxide microhemispherical shell resonators (μHSRs) with capacitive electrodes. A high aspect ratio silicon dioxide μHSR with a thickness of 2.6 μm and diameter of 910 μm, uniformly coated with 30 nm of platinum using ALD process, demonstrated Q of 19,100 at 19.17 kHz(More)
We report, for the first time, on the successful fabrication and operational characterization of electroplated Invar Micro-Hemispherical Shell Resonators (μHSR). The heat treatment of the samples and its effect on the quality factor (Q) of the resonators is studied. We show that thermal annealing shifts the coefficient of thermal expansion (CTE) of the(More)
A technique is proposed to employ the phase shifting capability of a MEMS resonator to form the basic component of a switchless quadrature phase shift keying (QPSK) scheme. The advantages of such an approach include direct baseband to RF modulation, no generation of intermodulation products since the resonator is operated linearly, and small size, cost, and(More)
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