Synergistic effect of total ionization dose and single event transient in bipolar operational amplifier LM158

BackgroundBipolar devices used in space radiation environment for a long time are simultaneously threatened by the total ionization dose (TID) effect and single event transient (SET), and there is a synergistic effect between TID and SET. The enhanced low dose rate sensitivity (ELDRS) effect unique to bipolar devices may affect the synergistic effect.PurposeThis study aims to investigate the physical mechanism of TID's impact on the SET in bipolar operational amplifier LM158.MethodsFirst of all, the LM158 samples were irradiated by 60Co γ-ray of a high dose rate of 0.1 Gy·s-1(Si) and a low dose rate of 1×10-4 Gy·s-1(Si). Then, the heavy ion (Tantalum) irradiation test was performed after the total dose was accumulated to 1 000 Gy(Si). The output single event transients of irradiated LM158 were observed by oscilloscope, and all the collected SETs were saved in computer and processed by MATLAB programming.ResultsThe experimental results show that the TID of bipolar operational amplifier LM158 causes the SET pulse amplitude to decrease and pulse width to expand. At the same time, compared with the high dose rate irradiation condition, the SET pulse width of LM158 is expanded by 50% under the low dose rate irradiation condition.ConclusionsThe study indicates that the interface trap charge accumulated in the bipolar transistor is the fundamental reason for the synergistic effect of TID and SET.