Simple and robust microcontroller-based acquisition system for differential capacitive sensors

• Differential capacitive sensors, especially if implemented as MEMS (Micro Electro Mechanical Systems) are a widely employed sensor solution, especially after the widespread adoption of the IoT (Internet of things) paradigm. These sensors target very different applications, including accelerometers, gyroscopes, barometers, just to mention a few, because they can take advantage from lower power consumption, better temperature coefficient and manufacturability. The readout circuit plays a central and fundamental role in ensuring optimal overall performance. In this paper, a frontend for interfacing differential capacitive sensors with microcontroller-based systems is discussed and performance is evaluated. In particular, the use of voltage mode is considered and, consequently, the stray capacitance can deeply affect the readouts. The proposed interface evaluates the mismatch between the current flowing in the two sensor equivalent capacitors and estimates the parasitic value. Additionally, the information about the current unbalance is used to improve the measurand estimation. In particular, the proposed approach is able to decrease of one order of magnitude the measurand estimation error, when large stray capacitance affects the sensor. © 2021 IEEE.

Nyckelord

AC excitation

Differential capacitive sensors

stray capacitance compensation

synchronous demodulation

Capacitance

Internet of things

MEMS

Microcontrollers

Acquisition systems

Equivalent capacitors

Lower-power consumption

Micro electro mechanical system

Microcontroller based systems

Microcontroller-based

Temperature coefficient

Capacitive sensors

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