| 摘要 |
PURPOSE:To obtain a high power gain, i.e., a low noise index and a wide AGC range in an UHF band by providing a second conductivity type drain region formed on a first conductivity type semiconductor layer and a second gate electrode formed through a gate insulating film on an annular groove surface which reaches the vicinity of a high concentration first conductivity type semiconductor layer around the drain region. CONSTITUTION:Parts of second gate electrodes 7, 7' are extended to the vicinity (1mum weak) of a low resistivity (0.01OMEGAcm) high concentration P-type semiconductor layer 11, a second gate electrode is grounded in a high frequency manner through the general using method of a dual gate MOS-FET by a large external pass capacitor, and a low resistivity substrate 11 is connected by an ohmic rear face metal electrode 12 provided on its rear face to the source lead of a package, and electrically held at a ground potential. That is, an n<+> type drain region 1 is surrounded substantially completely by second gate electrodes 7, 7' and the substrate 11, and resultantly shielded.
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