A switched-capacitor interface for capacitive sensors based on relaxation oscillators

Author

Cichocki, Andrzej ; Unbehauen, Rolf

Author_Institution

Warsaw Tech. Univ., Poland

Volume

39

Issue

5

fYear

1990

fDate

10/1/1990 12:00:00 AM

Firstpage

797

Lastpage

799

Abstract

A switched-capacitor (SC) interface for capacitive sensors based on a modified Martin´s relaxation oscillator is proposed. The output signal is the duty-cycle of a pulse-width modulated square-wave voltage or a binary-coded digital signal which is directly related to the capacitance ratio of an unknown capacitance and reference capacitance. The circuit can be implemented in a monolithic IC form using CMOS technology. It requires a relatively small device count integrable onto a small chip area and its suited particularly for the on-chip interface circuitry for microprocessors

Keywords

CMOS integrated circuits; electric sensing devices; relaxation oscillators; switched capacitor networks; CMOS; binary-coded digital signal; capacitive sensors; duty-cycle; microprocessors; modified Martin´s relaxation oscillator; monolithic IC; on-chip interface circuitry; pulse-width modulated square-wave voltage; reference capacitance; relaxation oscillators; switched-capacitor interface; CMOS integrated circuits; CMOS technology; Capacitance; Capacitive sensors; Digital modulation; Monolithic integrated circuits; Oscillators; Pulse modulation; Space vector pulse width modulation; Voltage;

fLanguage

English

Journal_Title

Instrumentation and Measurement, IEEE Transactions on

Publisher

ieee

ISSN

0018-9456

Type

jour

DOI

10.1109/19.58630

Filename

58630