Patent ID: 7132687

Claim:
A cellular phone comprising: a main body; a sound input portion; a sound output portion; operation switches; and a display portion, wherein the display portion comprises: a substrate; a switching thin film transistor formed over the substrate and including: a first channel region; a pair of first impurity regions formed in contact with the first channel region; a first gate electrode formed adjacent to the first channel region with a first gate insulating film interposed therebetween, and a current controlling thin film transistor formed over the substrate and including: a second channel region; a pair of second impurity regions formed in contact with the second channel region; a second gate electrode formed adjacent to the second channel region with a second gate insulating film interposed therebetween, wherein the first impurity region includes an n-type impurity element at a first concentration while the second impurity region includes the n-type impurity element at a second concentration, wherein the second concentration is higher than the first concentration.