MATRIX THERMAL IMAGE SENSOR WITH BOLOMETRIC PIXEL AND METHODOF REDUCING SPATIAL NOISE

The invention relates to matrix image sensors of the bolometric type, in which each pixel comprises a bolometric resistor (Rb) whose value varies according to the thermal flow received by the pixel. The resistor (Rb) is biased by a bias voltage of value Vpol. The current that passes through it is compensated for by a compensation current Icomp, the difference between these currents being integrated in order to produce a measurement signal. The bias voltage (or the compensation current) is adjusted pixel by pixel, for example during a calibration phase, so that all the pixels have an apparent identical sensitivity despite the dispersion of the nominal value of the bolometric resistor. The adjustment is carried out in an analogue manner by storing an individual voltage (VG) specific to each pixel in a sensitivity trimmer capacitor (Ca) specific to this pixel. The capacitor acts directly on the adjustment of the bias voltage or on other parameters playing a role in the sensitivity of the pixel (integration time for example). The spatial noise is thereby considerably reduced.