A Low-Power, Wide-Bandwidth, Three-Axis MEMS Accelerometer ASIC Using Beyond-Resonant-Frequency Sensing

This article presents a 16-bit wide-bandwidth (BW) high-performance (HP) three-axis micro-electromechanical system (MEMS) accelerometer readout application-specific integrated circuit (ASIC). It is the world's first accelerometer to use beyond-resonant-frequency sensing technique to extend the BW by digitizing and equalizing the full sensor response including the MEMS sensor resonance. The readout ASIC consists of dual signal paths: three 16-bit HP signal paths to sense frequency rich signals, such as acoustic or vibration, and one shared 12-bit low-power (LP) signal path to sense temperature and motion simultaneously. The ASIC is fabricated in 0.18-mu m CMOS technology and is packaged with two three-axis MEMS sensors achieving a 4-kHz, 25-mu g/root Hz, +/- 8-g accelerometer consuming 375 mu A and an 8-kHz, 59-mu g/root Hz, +/- 30-g accelerometer consuming 550 mu A. The proposed technique compensates the transfer function deviation from 4.6 and 8.9 dB to less than +/- 0.56 and +/- 0.52 dB in two accelerometer prototypes.