1. A Capacitance-Ratio-Modulated Current Front-End Circuit With Pulsewidth Modulation Output for a Capacitive Sensor Interface.
- Author
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Sheu, Meng-Lieh, Hsu, Wei-Hung, and Tsao, Lin-Jie
- Subjects
- *
CAPACITANCE meters , *ELECTRONIC circuits , *DETECTORS , *CAPACITANCE-voltage characteristics , *INTEGRATED circuits - Abstract
This paper presents a front-end circuit with pulsewidth modulation (PWM) output for a capacitive sensor interface. A single-MOSFET-based capacitance-ratio-modulated current (CRMC) circuit is proposed to transform the sensed capacitance into a current proportional to a capacitance ratio. The proposed single-MOSFET-based CRMC circuit not only saves a lot of chip area but also lowers power consumption. Then, a dual-slope integration circuit transforms further the modulated current into PWM output. A prototype chip is designed and fabricated with a 0.35- \mu\m complementary metal–oxide–semiconductor process and has a core area of 0.09 \mm^2. The measurement results of the prototype chip demonstrate an accuracy value of up to 9.3 bit with 54- \mu\W power consumption. The microwatt power consumption and the small chip area of the proposed front-end circuit make it very suitable for a capacitive sensor interface in smart sensor chips. [ABSTRACT FROM PUBLISHER]
- Published
- 2012
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