Highly sensitive MEMS frequency modulated accelerometer with small footprint

• Autor(a) principal: Esteves Moreira, Eurico
• Data de Publicação: 2020
• Outros Autores: Kuhlmann, Burkhard, Serra Alves, Filipe, Dias, Rosana Maria Alves, Cabral, Jorge, Gaspar, João, Rocha, Luís Alexandre Machado
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: https://hdl.handle.net/1822/71126
• topic: Accelerometer; Double-ended tuning fork (DETF) resonators; Frequency modulated; Micro-lever mechanism; Microelectromechanical systems (MEMS)

A single-axis resonant MEMS accelerometer is presented here. The goal is to achieve the maximum sensitivity on a set of predefined constraints: small footprint of 500 μm × 500 μm, vacuum operation under 150 Pa (requirement for a single-chip IMU) and fabrication using a Bosch silicon surface micromachining process. The sensor is composed by double-ended tuning fork resonators in differential architecture and a force amplification mechanism to increase its sensitivity. A complete characterization of the device was performed including closed-loop operation. A proportional-integral-derivative closed-loop controller architecture updates in real-time the excitation frequency to half the resonance frequency of the resonators. A scale-factor of 170 Hz/g and a non-linearity of 0.63 %FS (operation range of ±1 g) were experimentally measured. The relative sensitivities of 0.08 %Hz/g/nkg and 0.48 %Hz/g are among the highest reported for DETF-based devices. Long-term (700 μg/√Hz noise floor measured), dynamic and thermal drift measurements are also reported. The differential operation improved the thermal performance by 77 %.