Device for detecting electromagnetic radiation

A bolometric detector comprising:

• an array of resistive bolometers, each of the bolometers comprising a membrane suspended above a substrate and being associated with a biasing circuit capable of biasing said bolometer with a predetermined bias voltage,
• a rejection module capable of generating a common mode current,
• wherein the rejection module comprises:
• an estimation module for estimating a current that flows through the resistive bolometers when subjected to the bias voltage and made insensitive to the electromagnetic radiation, and
• a current generator which is controlled by the estimation module and generates the current estimated by the estimation module as a common mode current, and
• wherein the estimation module comprises:
• at least one thermal sensor measuring a temperature of substance;
• digital processing means for calculating the common mode current as a function of the measured temperature of the substrate and a thermal model of the resistive bolometer;
• and
• a measuring circuit capable of being connected to bolometer and the rejection module in order to measure the difference between the current that flows through the respective bolometer when it is biased and the common mode current generated by the rejection module.

A method of operating a device for detecting electromagnetic radiation comprising a resistive bolometer, and a biasing circuit capable of biasing said bolometer with a predetermined bias voltage, wherein said resistive bolometer comprises a membrane suspended above a substrate, the method comprising:

• subjecting the bolometer to the electromagnetic radiation;
• applying a bias voltage to the bolometer in order to make a current flow through the bolometer;
• generating a common mode current that is an estimation of a current that would flow through the bolometer subjected to the bias voltage if the bolometer was made insensitive to the electromagnetic radiation by:
• measuring a temperature of the substrate,
• calculating the common mode current as a function of the measured temperature of the substrate and a thermal model of the resistive bolometer, and
• generating the calculated common mode current,
• subtracting the generated common mode current from the current flowing through the bolometer, and
• measuring the resulting difference between the current flowing through the bolometer and the generated common mode current.