Patent ID: 6160404
Filing Date: 2000-12-12
Classification: F02D,G01N,G01R

Abstract:
A circuit for measuring the electrode current of a ceramic gas sensor for measuring a gas, the ceramic gas sensor having first and second sensor electrodes arranged in a heatable ceramic, the first sensor electrode functioning as a measuring electrode and the second sensor electrode functioning as a reference electrode, the circuit being a current measuring circuit connected to said first and second sensor electrodes and said current measuring circuit comprising:a current measuring shunt (R2) for conducting a measurement current flowing away from said first sensor electrode thereby causing a first voltage drop across said current measuring shunt (R2);a first circuit part for detecting said measurement current;a current feedback shunt (R1) connected to said second sensor electrode;a second circuit part for generating a current having a magnitude corresponding to the magnitude of said measurement current detected by said first circuit part;said second circuit part being connected to said current feedback shunt (R1) whereby said current generated by said second circuit part flows to said second sensor electrode via said current feedback shunt (R1) causing a second voltage drop across said current feedback shunt (R1); and,a third circuit part for amplifying the difference of said first and second voltage drops and converting said difference into a measurement signal referred to a reference potential.