CPC G01N 27/4163 (2013.01) [G01N 27/122 (2013.01); G01N 27/404 (2013.01)] | 20 Claims |
1. A sensor interface circuit for measuring a gas concentration and an impedance of an electrochemical gas sensor, the sensor interface circuit comprising:
an integrated circuit comprising a first node configured to be connected to a first electrode in the electrochemical gas sensor;
a first switch located within the integrated circuit, the first switch being configured to connect a first noise-suppression circuit from the first electrode to an electrical reference node in a gas sensing mode and disconnect the first noise-suppression circuit in an impedance testing mode; and
bias circuitry configured to provide a bias signal to an electrode in the electrochemical gas sensor, the bias circuitry configured to perform operations comprising:
applying a constant bias signal to the first node; and
in the impedance testing mode with the constant bias signal being applied, applying a time-varying excitation signal to the first node.
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