Patent ID: 7282763

Claim:
A field effect transistor comprising: an insulating substrate; a semiconductor thin film formed on the insulating substrate; a gate insulating film formed on the semiconductor thin film; a first gate electrode with a length and a width formed on the gate insulating film; a first region and at least one second region having a first conductivity type and being formed on or in a surface of the semiconductor thin film on opposite sides of the first gate electrode in the length direction thereof; at least one third region having a second conductivity type opposite the first conductivity type arranged side-by-side with the second region in the width direction of the first gate electrode; a conductive thin film connected with the second region and the third region; a second gate electrode with a length and a width formed on the gate insulating film along the second region; and a fourth region having the first conductivity type formed on or in the surface of the semiconductor thin film and on an opposite side of the second region with respect to the second gate electrode in a length direction thereof, one of the first and the fourth regions being independently used as an output region according to a bidirectional circuit operation of the field effect transistor and without application of a fixed bias potential to the third region.