Abstract: A semiconductor device comprising a field effect transistor of the lateral or vertical DMOST type having a source zone of the one conductivity type, an adjoining channel region of the other conductivity type, a drain zone of the one conductivity type and a weakly doped drift region located between the drain zone and the channel region. According to the invention a second gate electrode located on the side of the drain zone and separated from the first gate electrode is disposed on the insulating layer above the channel zone behind the first gate electrode located on the side of the source zone. The length L.sub.2 of the part of the second gate electrode located above the channel zone is at least equal to that of the part of the first gate electrode located above the channel zone. As a result, a high value of the mutual conductance g.sub.m as well as good linearity can be obtained.