Patent ID: 7825435

Claim:
A composite semiconductor device comprising: (A) a semiconductor rectifier having an anode and a cathode electrode; (B) a unipolar field effect transistor comprising: (a) a source electrode coupled to said cathode electrode of said semiconductor rectifier; (b) a drain electrode; and (c) a gate electrode connected to said anode electrode of said semiconductor rectifier; (d) said unipolar field effect transistor being adapted to turn on when a voltage is impressed between said anode electrode of said semiconductor rectifier and said drain electrode of said field effect transistor in a direction to forward bias said semiconductor rectifier; (e) a current flowing between said gate electrode and said drain electrode of said field effect transistor when said field effect transistor is on being less than a current flowing between said anode and said cathode electrode of said semiconductor rectifier; (f) a voltage withstanding capability between said drain electrode and said gate electrode of said field effect transistor being higher than that of said semiconductor rectifier when a voltage is impressed between said anode electrode of said semiconductor rectifier and said drain electrode of said field effect transistor in a direction to reverse bias said semiconductor rectifier; (C) a first terminal electrically connected to said anode electrode of said semiconductor rectifier and said gate electrode of said field effect transistor; and (D) a second terminal electrically connected to said drain electrode of said field effect transistor.