Physical origin of the excess thermal noise in short channel MOSFETs

The physical origin of the excess thermal noise in short channel MOSFETs is explained based on numerical noise simulation. The impedance field representation and extraction method demonstrate that the drain current noise is dominated by source side contributions. Analysis identifies local ac channel resistance variations as the primary controlling factor. The nonlocal nature of velocity results in a smaller derivative of the velocity with respect to the field which in turn causes a higher local ac resistance near the source junction.