AlGaAs/GaAs/AlGaAs DHBT's for high-temperature stable circuits

High-temperature devices are required for a large number of industrial applications. In order to demonstrate the feasibility of a high temperature operating circuit on GaAs an operational amplifier was designed and fabricated. A corresponding technology for transistors and circuits for operation up to 300/spl deg/C with AlGaAs/GaAs/AlGaAs DHBT's is presented. For the amplifier circuit an open loop gain of 49.5 dB at room temperature and 35.8 dB at 200/spl deg/C was measured, which is in good agreement with the circuit simulation. High temperature stability has been proven by a storage test at 400/spl deg/C over 1000 h for the ohmic contact metallization and 200 h for the transistors.<
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