A low-power interface circuit for multi-sensor applications

This paper presents a low-power generic readout circuit for capacitive and resistive complementary metaloxide- semiconductor (CMOS) micro-electro-mechanical-system (MEMS) sensors. This readout architecture can be scaled to even more sensors to achieve chip area and power consumption efficient. An incremental sigma-delta analog-to-digital converter (ΣΔ ADC) is used for providing multiplexed digital output. A demonstration chip was implemented in a 0.18-μm CMOS MEMS process, which integrates a three-axis accelerometer, the readout circuit, and an ARM M0 microprocessor. The chip area is 3.5×2.5 mm
²
and the interface circuit with ADC draw only 120 mA of current from a 1.8-V supply. A magneto-resistance-type three-axis magnetic sensor is manufactured via extra post processes. This chip is designed to demonstrate a monolithic virtual gyroscope, which is a popular solution for low-power and low-cost inertial applications.