Wafer-level-packaged HARPSS+ MEMS platform: Integration of robust timing and inertial measurement units (TIMU) on a single chip

Wen, Haoran; Daruwalla, Anosh; Jeong, Yaesuk; Gupta, Pramod; Choi, Jaehyun; Liu, Chang-Shun; Ayazi, Farrokh

doi:10.1109/plans.2018.8373389

Cited by 25 publications

(14 citation statements)

References 9 publications

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“…Capacitive bulk acoustic wave (BAW) gyroscopes circumvent this problem by increasing the resonance frequency of the device using stiff bulk vibration modes of the structure at the cost of intricate fabrication processing to realize high-aspect-ratio gaps [13][14][15][16] . Bulk-mode resonant devices in the megahertz frequency range have also been proven to offer superior shock and vibration immunity [17][18][19][20] .…”

Section: Introductionmentioning

confidence: 99%

Eigenmode operation of piezoelectric resonant gyroscopes

Hodjat-Shamami

Ayazi

2020

Microsyst Nanoeng

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The theory of eigenmode operation of Coriolis vibratory gyroscopes and its implementation on a thin-film piezoelectric gyroscope is presented. It is shown analytically that the modal alignment of resonant gyroscopes can be achieved by applying a rotation transformation to the actuation and sensing directions regardless of the transduction mechanism. This technique is especially suitable for mode matching of piezoelectric gyroscopes, obviating the need for narrow capacitive gaps or DC polarization voltages. It can also be applied for mode matching of devices that require sophisticated electrode arrangements for modal alignment, such as electrostatic pitch and roll gyroscopes with slanted electrodes utilized for out-of-plane quadrature cancellation. Gyroscopic operation of a 3.15 MHz AlN-on-Si annulus resonator that utilizes a pair of high-Q degenerate in-plane vibration modes is demonstrated. Modal alignment of the piezoelectric gyroscope is accomplished through virtual alignment of the excitation and readout electrodes to the natural direction of vibration mode shapes in the presence of fabrication nonidealities. Controlled displacement feedback of the gyroscope drive signal is implemented to achieve frequency matching of the two gyroscopic modes. The piezoelectric gyroscope shows a mode-matched operation bandwidth of ~250 Hz, which is one of the largest open-loop bandwidth values reported for a mode-matched MEMS gyroscope, a small motional resistance of ~1300 Ω owing to efficient piezoelectric transduction, and a scale factor of 1.57 nA/°/s for operation at atmospheric pressure, which greatly relaxes packaging requirements. Eigenmode operation results in an ~35 dB reduction in the quadrature error at the resonance frequency. The measured angle random walk of the device is 0.86°/√h with a bias instability of 125°/h limited by the excess noise of the discrete electronics.

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Section: Introductionmentioning

confidence: 99%

Eigenmode operation of piezoelectric resonant gyroscopes

Hodjat-Shamami

Ayazi

2020

Microsyst Nanoeng

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“…Mode matching is accomplished with laser ablation trimming to bring the frequency of two modes within -3dB bandwidth. The characterized AlN BAW gyroscope shows a noise performance very close to the capacitive counterparts in similar size 35 . In addition, the as-born and post-trim frequency response data of several AlN BAW gyroscopes batch-fabricated on a 8-inch wafer are provided, showing good repeatability as a promising platform for low noise, wide bandwidth MEMS gyroscopes.…”

Section: Introductionmentioning

confidence: 61%

Multi-Coefficient Eigenmode Operation – Breaking Through 10°/hr Open-Loop Bias Instability in Wideband Aluminum Nitride Piezoelectric BAW Gyroscopes

Liu

Wen

Ayazi

2022

Preprint

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This paper introduces a modification to the eigenmode operation of resonant gyroscopes. The so-called multi-coefficient eigenmode operation can improve cross-mode isolation due to spatially non-orthogonal imperfection, which is one of the causes of residual quadrature error in conventional eigenmode operation. A 1400µm annulus aluminum nitride (AlN) on Silicon bulk acoustic wave (BAW) resonator with gyroscopic in-plane bending modes at 2.98MHz achieves near 60dB cross-mode isolation when operated as a gyroscope using multi-coefficient eigenmode architecture. The as-born frequency mismatches in multiple devices are compensated by physical laser trimming as an alternative to the displacement feedback tunning mechanism. The demonstrated AlN piezoelectric BAW gyroscope shows a large open-loop bandwidth of 150Hz and a high scale factor of 9.5nA/°/s on a test board in a vacuum chamber. The measured angle random walk is 0.145°/√hr, and the bias instability is 8.6°/hr, showing significant improvement compared to the previous eigenmode AlN BAW gyroscope. The result from this paper proves that with multi-coefficient eigenmode operation, the piezoelectric AlN BAW gyroscopes can have a comparable noise performance as their capacitive counterpart while having the unique advantage of large open-loop bandwidth and not requiring large DC polarization voltages.

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“…Mode matching is accomplished with laser ablation trimming to bring the frequency of the two modes within −3 dB bandwidth. The characterized AlN BAW gyroscope shows a noise performance very close to the capacitive counterparts of similar size 35 . In addition, the as-born and post-trim frequency response data of several AlN BAW gyroscopes batch-fabricated on an 8-inch wafer are provided, showing good repeatability and a promising platform for low noise, wide bandwidth MEMS gyroscopes.…”

Section: Introductionmentioning

confidence: 63%

Multi-coefficient eigenmode operation—breaking through 10°/h open-loop bias instability in wideband aluminum nitride piezoelectric BAW gyroscopes

2023

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In this paper, a modification to the eigenmode operation of resonant gyroscopes is introduced. The multi-coefficient eigenmode operation can improve cross-mode isolation due to electrode misalignments and imperfections, which is one of the causes of residual quadrature errors in conventional eigenmode operations. A 1400 µm annulus aluminum nitride (AlN) on a silicon bulk acoustic wave (BAW) resonator with gyroscopic in-plane bending modes at 2.98 MHz achieves a nearly 60 dB cross-mode isolation when operated as a gyroscope using a multi-coefficient eigenmode architecture. The as-born frequency mismatches in multiple devices are compensated by physical laser trimming. The demonstrated AlN piezoelectric BAW gyroscope shows a large open-loop bandwidth of 150 Hz and a high scale factor of 9.5 nA/°/s on a test board with a vacuum chamber. The measured angle random walk is 0.145°/√h, and the bias instability is 8.6°/h, showing significant improvement compared to the previous eigenmode AlN BAW gyroscope. The results from this paper prove that with multi-coefficient eigenmode operations, piezoelectric AlN BAW gyroscopes can achieve a noise performance comparable to that of their capacitive counterpart while having the unique advantage of a large open-loop bandwidth and not requiring large DC polarization voltages.

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Wafer-level-packaged HARPSS+ MEMS platform: Integration of robust timing and inertial measurement units (TIMU) on a single chip

Cited by 25 publications

References 9 publications

Eigenmode operation of piezoelectric resonant gyroscopes

Eigenmode operation of piezoelectric resonant gyroscopes

Multi-Coefficient Eigenmode Operation – Breaking Through 10°/hr Open-Loop Bias Instability in Wideband Aluminum Nitride Piezoelectric BAW Gyroscopes

Multi-coefficient eigenmode operation—breaking through 10°/h open-loop bias instability in wideband aluminum nitride piezoelectric BAW gyroscopes

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