Logic Upset Level of GaAs SRAMs for Pulsed Ionizing Radiation

The first pulsed ionizing radiation logic upset measurements on GaAs 256-bit static RAMs are reported and analyzed. The circuit design utilized GaAs enhancement junction field-effect transistors (E-JFETs) with resistive loads and direct-coupled field-effect transistor logic (DCFL). The test results demonstrated upset levels for the most sensitive cells in the range of 6 × 109 to 1 × 1010 rad(GaAs)/s. All evaluated memories contained a core of hard memory cells which retained their logic state up to a dose rate of 3 × 1011 rad(GaAs)/s. A tentative model for memory state upset is presented, which includes the semi-insulating substrate currents generated by ionizing radiation and predicts the observed behavior of the static RAMs tested.