Gas concentration measuring apparatus compensating for error component of output signal

摘要

A gas concentration measuring apparatus is provided which includes a gas concentration sensor consisting of a pump cell, a sensor cell, and a monitor cell. The pump cell works to determine the concentration of O2. The sensor cell works to decompose an oxygen containing gas such as NOx and provide an output indicative of the concentration of NOx. The apparatus also includes an applying voltage determining circuit which looks up a predetermined voltage-to-current relation to determine a target voltage to be applied to the pump cell as a function of the current produced by the pump cell so as to preclude the pump cell from decomposing the oxygen containing gas component, thereby minimizing an error in determining the concentration of oxygen containing gas as a function of the output of the sensor cell.