A novel low-cost capacitive-sensor interface

Author

Van der Goes, Frank M L ; Meijer, Gerard C M

Author_Institution

Dept. of Electr. Eng., Delft Univ. of Technol., Netherlands

Volume

45

Issue

2

fYear

1996

fDate

4/1/1996 12:00:00 AM

Firstpage

536

Lastpage

540

Abstract

This paper describes the design of a new capacitive sensor interface. The interface is based on the use of a novel type of oscillator whose frequency is insensitive to low- and high-frequency interfering signals by the application of a third order high-pass filter and special dither techniques. The fully integrated 0.7 μm CMOS circuit shows an inaccuracy of less than 100 aF with respect to a 2 pF reference capacitor over a -30° to +70°C temperature range. The applied measurement concept guarantees high stability, high accuracy and a negligible influence of parasitic capacitances without the need for calibration

Keywords

CMOS integrated circuits; electric sensing devices; high-pass filters; interference suppression; relaxation oscillators; signal processing; switched current circuits; -30 to 70 C; 0.7 mum; 100 aF; 2 pF; CMOS circuit; accuracy; calibration; design; dither technique; high-frequency interfering signals; inaccuracy; low-cost capacitive-sensor interface; low-frequency interfering signals; oscillator; parasitic capacitances; stability; third order high-pass filter; Capacitance measurement; Capacitive sensors; Capacitors; Circuit stability; Filters; Frequency; Integrated circuit measurements; Oscillators; Parasitic capacitance; Temperature distribution;

fLanguage

English

Journal_Title

Instrumentation and Measurement, IEEE Transactions on

Publisher

ieee

ISSN

0018-9456

Type

jour

DOI

10.1109/19.492782

Filename

492782