A combined comb / bulk mode gyroscope structure for enhanced sensitivity

Elsayed, Mohannad Y.; Nabki, Frédéric; El-Gamal, M.N.

doi:10.1109/memsys.2013.6474325

Cited by 11 publications

(7 citation statements)

References 7 publications

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“…The fabrication process of planar micro-resonators is compatible with the widely served MEMS technology [22,23,24]. Researchers in this field aim their attention at optimizing structure designs to boost the Q factor of micro-resonators and to increase the mechanical sensitivity of CVGs [25,26].…”

Section: Introductionmentioning

confidence: 99%

A Lumped Mass Model for Circular Micro-Resonators in Coriolis Vibratory Gyroscopes

et al. 2019

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Coriolis vibratory gyroscopes (CVGs) with circular micro-resonators, such as hemispherical, ring, and disk resonators, exhibit excellent performances and have extraordinary potential. This paper discusses a generalized lumped mass model for both 3D and planar circular micro-resonators, establishing the relationship between the modal effective mass, the modal equivalent force, and the point displacement of the resonator. The point displacement description of a continuous circular resonator’s motion is defined from the view of capacitance measurement. The modal effective mass is, consequently, determined by the kinetic and the potential energy of the structure and is computed with numerical simulations. Moreover, the modal equivalent force, which can be theoretically calculated for any configuration of discrete electrodes, is deduced by using the concept of force density and the force distribution function. By utilizing the lumped mass model in this paper, the stiffness softening, the mode tuning, and the quadrature correction of the micro-resonators are investigated in detail. The theoretical model is verified by both the finite element method (FEM) and the experiments.

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Section: Introductionmentioning

confidence: 99%

A Lumped Mass Model for Circular Micro-Resonators in Coriolis Vibratory Gyroscopes

et al. 2019

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“…Resonators can be classified based on their vibration modes as either flexural or bulk-mode devices. Bulk-mode devices typically exhibit high stiffness, and are consequently less prone to thermoelastic damping, compared to flexural devices, allowing them to achieve large quality factors (>10,000), even at atmospheric pressure [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16]. In [2,3,4,5,6,7], bulk-mode resonators including Lamé-mode and wine glass mode devices with quality factors in the 106 range were presented based on capacitive actuation.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, capacitive bulk-mode devices typically exhibit lower transduction efficiencies compared to piezoelectric devices, which translate to higher losses and motional resistances. This can be accounted for by either enhancing the transduction, e.g., sub-micron gaps realized by complex fabrication processes [11,12,13], high voltages [1,2,3,4,5,6,7,14], added transducer combs [15,16], movable electrodes for gap closing [17,18], or increasing the gain for the transimpedance amplifier (TIA) in order to sustain oscillation. Several transimpedance topologies have been reported in the literature for MEMS-based oscillator applications [19,20,21,22,23,24,25,26].…”

Section: Introductionmentioning

confidence: 99%

A Sub-mW 18-MHz MEMS Oscillator Based on a 98-dBΩ Adjustable Bandwidth Transimpedance Amplifier and a Lamé-Mode Resonator

Bouchami

Elsayed

Nabki

2019

Sensors

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This paper presents a microelectromechanical system (MEMS)-based oscillator based on a Lamé-mode capacitive micromachined resonator and a fully differential high-gain transimpedance amplifier (TIA). The proposed TIA is designed using TSMC 65 nm CMOS technology and consumes only 0.9 mA from a 1-V supply. The measured mid-band transimpedance gain is 98 dB Ω and the TIA features an adjustable bandwidth with a maximum bandwidth of 142 MHz for a parasitic capacitance C P of 4 pF. The measured input-referred current noise of the TIA at mid-band is below 15 pA/ Hz . The TIA is connected to a Lamé-mode resonator, and the oscillator performance in terms of phase noise and frequency stability is presented. The measured phase noise under vacuum is −120 dBc/Hz at a 1-kHz offset, while the phase noise floor reaches −127 dBc/Hz. The measured short-term stability of the MEMS-based oscillator is ±0.25 ppm.

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“…As a result, the structure design, fabrication process, and post treatment of the resonator has been optimized. Bulk mode resonators have been developed to achieve an ultra-high Q-factor [15,16,17]. Considering possible material defects, surface loss, and residual stress introduced in fabrication process, kinds of post-processes have been researched to improve the Q-factor of as-fabricated resonators [18,19,20].…”

Section: Introductionmentioning

confidence: 99%

A Study on the Trimming Effects on the Quality Factor of Micro-Shell Resonators Vibrating in Wineglass Modes

Lü

Xiao

et al. 2019

Micromachines

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Frequency trimming based on mass and stiffness modification is an important post-fabrication process for micro-shell resonators (MSRs). However, the trimming effects on the quality factor are seldom studied, although they may have great influence on the performance of the resonator. This paper presents a study on the quality factor (Q-factor) variation of trimmed micro-shell resonators (MSR). Thermoelastic damping (QTED) and anchor loss (Qanchor) are found to be the dominant energy loss mechanisms resulting in the reduction of the overall Q-factor, according to finite element method (FEM). The effects of different trimming methods on QTED and Qanchor are studied here, respectively. It is found that trimming grooves ablated in the rim of the resonator can cause a ~1–10% reduction of QTED, and the length of trimming groove is positively related to the reduction of QTED. The reduction of QTED caused by the mass adding process is mainly related to the thermal expansion coefficient and density of the additive and contact area between the resonator and additive masses. Besides, the first and second harmonic errors caused by asymmetrical trimming can cause a 10–90% reduction of Qanchor. Finally, trimming experiments were conducted on different resonators and the results were compared with FEM simulation. The work presented in this paper could help to optimize the trimming process of MSRs.

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A combined comb / bulk mode gyroscope structure for enhanced sensitivity

Cited by 11 publications

References 7 publications

A Lumped Mass Model for Circular Micro-Resonators in Coriolis Vibratory Gyroscopes

A Lumped Mass Model for Circular Micro-Resonators in Coriolis Vibratory Gyroscopes

A Sub-mW 18-MHz MEMS Oscillator Based on a 98-dBΩ Adjustable Bandwidth Transimpedance Amplifier and a Lamé-Mode Resonator

A Study on the Trimming Effects on the Quality Factor of Micro-Shell Resonators Vibrating in Wineglass Modes

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