Patent ID: 8523427

Claim:
An apparatus comprising a sensor device formed on a semiconductor substrate, the sensor device comprising: a thermal radiation sensor including an infrared radiation sensing cell and a first shielded infrared radiation referencing cell spatially separated from each other on the semiconductor substrate, the first shielded infrared radiation referencing cell and the infrared radiation sensing cell co-operating to provide a first output signal indicative of temperature fluctuations resulting from incident radiation, wherein the infrared radiation sensing cell is exposed to incident infrared radiation and the first shielded infrared radiation referencing cell is shielded from incident infrared radiation; and a gradient sensor including a second shielded infrared radiation referencing cell and at least one of the first shielded infrared radiation referencing cell or a third shielded infrared radiation referencing cell, wherein the gradient sensor is configured to provide a second output signal indicative of a temperature gradient experienced by the thermal radiation sensor, wherein the cells of the gradient sensor are shielded from incident infrared radiation, wherein the second output signal is operably combined with the first output signal to effect a calibration of the first output signal.