A relaxation-oscillator-based interface for high-accuracy ratiometric signal processing of differential-capacitance transducers

Author

Mochizuki, Kouji ; Watanabe, Kenzo ; Masuda, Takashi ; Katsura, Motoyasu

Author_Institution

Numazu Coll. of Technol., Japan

Volume

47

Issue

1

fYear

1998

fDate

2/1/1998 12:00:00 AM

Firstpage

11

Lastpage

15

Abstract

For high-accuracy signal processing of differential-capacitance transducers, an interface circuitry is developed based on a relaxation oscillator. Two capacitors of the transducer are multiplexed by diode switches to form the op-amp-based integrator. The duty ratio of the oscillator output then measures the ratio of two capacitances. A circuit analysis shows that the interface can detect the capacitance change as small as 0.01% of the total capacitance. Experimental results are also given to confirm the analysis

Keywords

analogue processing circuits; capacitive sensors; pressure measurement; relaxation oscillators; signal processing equipment; transducers; circuit analysis; differential-capacitance transducers; diode switches; duty ratio; integrator; interface; interface circuitry; multiplexed; operational amplifier; pressure measurement; ratiometric signal processing; relaxation-oscillator; signal processing; Capacitance measurement; Capacitors; Circuit analysis; Diodes; Integrated circuit measurements; Operational amplifiers; Oscillators; Signal processing; Switches; Transducers;

fLanguage

English

Journal_Title

Instrumentation and Measurement, IEEE Transactions on

Publisher

ieee

ISSN

0018-9456

Type

jour

DOI

10.1109/19.728780

Filename

728780