Total dose hardness of microwave GaAs field effect transistors

Five types of GaAs MESFET devices were tested, taking into account products from four manufacturers. The test conditions were set to match as nearly as possible the actual conditions of use in a satellite application. The parts were mounted on tuned, flight-type RF substrates. Most were installed in one or two stage amplifiers. RF measurements were made in a controlled temperature room on a special computer-aided measurements system. The RF gain was found to be extremely stable up to a dose of 2 x 10 to the 7th rad. Thereafter the gain decreased gradually. The operating power had no effect on the degradation when measured over the full range of input power.