Pixel readout chip for the ATLAS experiment

Pixel detectors with a high granularity and a very large number of sensitiv e elements (cells) are a very recent development used for high precision pa rticle detection. At the Large Hadron Collider LHC at CERN (Geneva) a pixel detector with 1.4 * 10(8) individual pixel cells is developed for the ATLA S detector. The concept is a hybrid detector consisting of a pixel sensor c onnected to a pixel electronics chip by bump and flip chip technology in on e-to-one cell correspondence. The development and prototype results of the pixel front end chip are presented together with the physical and technical requirements to be met at LHC. Lab measurements are reported.