Read and clear readout circuit and method of operation of an ir sensing

Abstract

The invention relates to a read and clear readout circuit and a method of operation of an IR sensing array. The invention eliminates 'readout circuit lag' which reduces transient response for an individual sensor, and reduces angular resolution of an array. 'Readout circuit lag' also emphasizes longer duration IR background causing unwanted saturation and restriction of the dynamic range. Readout circuit lag arises from the capacitance of the sensor elements and the capacitance of the readout circuit at a node to which the sensor elements are periodically coupled for readout, the IR induced charge being partitioned between these capacitances, with that attributable to the sensor capacitance not being injected, causing readout circuit lag. Elimination of such lag is achieved by following each readout step, with a clear or clear and skim step that removes charge to the clear level or to the skim level, precluding the lag earlier described.