| 摘要 |
PURPOSE: To provide a method of improving measuring precision by eliminating need of amplifying noise or offset elements in an oxygen ion concentration proportional sensor provided in an exhaust system for an internal combustion engine. CONSTITUTION: In a method and a circuit, an output signal to express a pumping current IP necessary for equalizing diffusion of oxygen between a detection cell 112 and a pumping cell 101 is generated in an oxygen ion concentration proportional sensor provided in an exhaust system for an internal combustion engine. Though it is insulated from the pumping current IP, a duplicate current IPREP to express this is generated. Next, the duplicate current IPREP is supplied to a load resistor 120 to generate the output signal. The duplicate current IPREP is generated simultaneously with the pumping current IP as it is insulated from it, thereby need of separately amplifying the detected pumping current IP can be eliminated. |
