| 摘要 |
PROBLEM TO BE SOLVED: To provide a protection circuit of a field effect transistor that can be manufactured, without increasing restrictions on pattern layout processes. SOLUTION: The protection circuit 10 of the field effect transistor is the protection circuit of a Schottky gate HFET. In the protection circuit 10, two sets of diode units 16, where forward and backward diodes 12 and 14 are connected in cascade, are connected in series. In this case, a gate wire Vgg connected to the gate electrode of the HFET is grounded via the protection circuit 10. The diodes 12 and 14 are integrated with the Schottky gate HFET for protecting from surge damage and are composed as a Schottky barrier diode, consisting of an n+-GaAs cap layer formed on a GaAs substarte, and a Schottky electrode formed on the n+-GaAs cap layer.
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