A 4 kHz, 25 μg/√Hz, 3-Axis MEMS Accelerometer ASIC Using Beyond-Resonant-Frequency Sensing

Micro-electromechanical systems (MEMS) accelerometers are widely used in consumer, industrial, and automotive applications [1]. Typically, capacitive MEMS accelerometers bandwidth (BW) are in the range of a few hundred hertz to around a few kilohertz, but to capture frequency-rich signals, such as acoustic or vibration signals, it is desirable to have wide-bandwidth MEMS accelerometers. This bandwidth is often limited by the resonant frequency $\left(f_{0}\right)$ of the MEMS sensors as a sensor with a higher f
0
has a lower sensitivity reducing the signal-to-noise ratio (SNR). Furthermore, the out-of-band sensor resonance remains sensitive to acceleration, so an out-of-band excitation could potentially put the sensor in an over-range event or cause internal ASIC signals to clip resulting in an offset or a linearity degradation. This paper proposes the world’s first accelerometer readout ASIC to sense beyond the f
0
of the MEMS sensor.