BPN817: Ultra-Low Power AlN MEMS-CMOS Microphones and Accelerometers


State-of-the-art (SOA) physical sensors used to monitor changes in the environment require active electronics that continuously consume power (in the order of mW) limiting the sensor lifetime to months or less. This project targets the integration of low frequency sensors with wake-up electronics that operates below 10nW (50dB lower than the SOA) and achieve high probability of detection (POD) (>95%) and low false alarm rate (FAR) (<1h^-1). To improve the sensor performance at low frequencies we design piezoelectric AlN MEMS microphones and accelerometers with high voltage sensitivities, CMOS circuits with low bias current that operate in subthreshold, and lower the interconnect parasitics (<50fF) by directly bonding both MEMS and CMOS wafers. In particular, the sensor output voltage is boosted by 1) segmenting and stacking the electrodes in series, and 2) optimizing the size, number of electrodes and materials that form the multilayer structure. Regarding to the circuit, we exploit the multiple threshold voltages that are available in the process to reduce leakage on switches, increase input gain, and decrease overdrive voltage in current mirrors. Finally, we achieve the detection specs (POD and FAR) by implementing a programmable 4-stage comparator that allows us to adjust the circuit threshold according to the maximum level of input signal.

Project end date: 01/26/18

Publication date: 
August 13, 2017
Publication type: 
BSAC Project Materials (Final/Archive)
PREPUBLICATION DATA - ©University of California 2017

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