An in-plane 3-axis inertial measurement unit with 16-bit over-sampled capacitive readout ASIC (Electron devices: 第15回先端半導体デバイスの基礎と応用に関するアジア・太平洋ワークショップ(AWAD2007))

概要

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A high performance inertial measurement unit (IMU) with fully differential, 16-bit over-sampled capacitive readout circuit is presented. The IMU can measure the x and y axis accelerations and z axis rotation. The MEMS sensing elements are fabricated using the sacrificial bulk micromachining (SBM) process. The sensor interface circuit is fabricated using a standard 0.18-μm CMOS process. The input capacitive amplifier adopts a fully-differential, chopper-stabilized switched capacitor (SC) architecture to obtain low noise characteristics. The output of input amplifier, modulated with the chopping frequency, is converted to a digital signal by 12-bit algorithmic analog-to-digital converter (ADC), to achieve a high resolution while maintaining a low power. The digital signal is demodulated in a digital demodulator, which removes non-ideal behaviors of a multiplier. The white-noise level of the demodulated signal is effectively reduced by a subsequent decimation filter, and then 16-bit acceleration and rotation signals are obtained. The SPI and I2C interface are integrated to enhance the user-connectivity. The fabricated system is applicable for automotive systems, such as electronic stability program (ESP).
社団法人電子情報通信学会の論文
2007-06-18