Casio Exilim EX-100 has a 1/1.7" sensor with dimensions of 7.44 x 5.58 mm and sensor area of 41.52mm2.
Casio EX-100's sensor is 41% larger than the average Compact sensor in its class. In cases where all the other parameters are the same between two cameras, the one with the larger sensor collects more light per pixel and performs better (less noise) in low light / High ISO conditions . Larger sensors also give the photographer more control on the depth of field.
Read our detailed Casio EX-100 Review