Abstract: A semiconductor device has a linear current-to-voltage characteristic through the origin of coordinates and additionally a bi-directional structure. The typical device contains an oxide layer on top of a p.sup.- doped substrate. On top of this oxide layer a n-type drift region is created which forms a longitudinal n-drift region. The n-drift region comprises at each end a low doped p-type well which has a portion with strongly doped p.sup.+ semiconductor material which will constitute contacting to either a source or a drain electrode. Each p-type well additionally contains a n.sup.+ area and additionally on top of said p-type well a gate electrode, whereby the n.sup.+ doped area is positioned in the p-well between a gate and a drain electrode or a gate and a source electrode, respectively. Thus a bi-directional double DMOS structure is created having a common drift region.

Abstract: A high frequency MOS transistor structure with an extended drift region, which modulates the resistance in the drift region of the MOS transistor. The extended gate layer is obtained by an extra semiconductor layer forming a second MOS structure on top of a thin gate oxide layer. The electrical field will then be uniformly distributed laterally in the extended drift region. This design makes it possible to produce a MOS transistor with a short channel length and an extended drift region with low doping concentration and still having very low on-resistance together with a high breakdown voltage.