This invention relates generally to semiconductor integrated circuit devices and more particularly, to techniques which can be effectively applied to semiconductor integrated circuit devices having Schlottky gate type field effect transistors (hereinafter referred to as "MESFETs").
It is a recent trend in semiconductor integrated circuit devices to arrange MESFETs on a semi-insulator substrate made of gallium aresenide (GaAs) having great carrier mobility in order to increase operation speed. In the semiconductor integrated circuit devices having this GaAs substrate, however, so-called "electrostatic destruction", that is, the breakdown of an input stage circuit connected to input terminals (bonding pads) by excessive electrostatic energy, is likely to occur in the same way as in semiconductor integrated circuit devices using a silicon substrate.
Therefore, an electrostatic destruction protect circuit is disposed between the input terminal and the input stage circuit, as disclosed, for example, in the article "CDFL Circuit Approach For GaAs D-MESFET IC'S" reported by R. C. Eden in GaAs IC Symposium, October, 1984. This electrostatic destruction protect circuit consists of a resistance element which mitigates the excessive current and a clamp diode which clamps the excessive current.