Gas sensor

Abstract

A gas sensor includes a feedback circuit part and a sensor circuit part. The feedback circuit part includes a reference resistor and a first temperature sensing element which are connected in series, a first heater resistor that heats the first temperature sensing element, and a first amplifier circuit that controls the amount of current to flow in the first heater resistor based on an internal potential. The sensor circuit part includes a second temperature sensing element and a second heater resistor that heats the second temperature sensing element. A current according to the output of the first amplifier circuit flows in the second heater resistor. With this configuration, it is possible to automatically change the amount of current to flow in the second heater resistor according to ambient temperature without digital processing to thereby heat the second temperature sensing element to a constant temperature.

Dependencies are inferred from the claim text.