A Capacitance-To-Digital Converter for MEMS Sensors for Smart Applications

Sensors

Richard Gaggl¹  Javier Pérez Sanjurjo²  Enrique Prefasi²  Cesare Buffa³ 

[1] Sensors, Villach 9500, Austria;Electronic Technology Department, Carlos III University of Madrid, Madrid 28911, Spain;;Infineon Technologies, RF &

关键词: MEMS;    CDC;    pressure sensor;    capacitive sensors;    dual-slope;    low power;   

DOI  :  10.3390/s17061312

来源: DOAJ

【 摘 要 】

The use of MEMS sensors has been increasing in recent years. To cover all the applications, many different readout circuits are needed. To reduce the cost and time to market, a generic capacitance-to-digital converter (CDC) seems to be the logical next step. This work presents a configurable CDC designed for capacitive MEMS sensors. The sensor is built with a bridge of MEMS, where some of them function with pressure. Then, the capacitive to digital conversion is realized using two steps. First, a switched-capacitor (SC) preamplifier is used to make the capacitive to voltage (C-V) conversion. Second, a self-oscillated noise-shaping integrating dual-slope (DS) converter is used to digitize this magnitude. The proposed converter uses time instead of amplitude resolution to generate a multibit digital output stream. In addition it performs noise shaping of the quantization error to reduce measurement time. This article shows the effectiveness of this method by measurements performed on a prototype, designed and fabricated using standard 0.13 µm CMOS technology. Experimental measurements show that the CDC achieves a resolution of 17 bits, with an effective area of 0.317 mm2, which means a pressure resolution of 1 Pa, while consuming 146 µA from a 1.5 V power supply.

【 授权许可】

Unknown