Degradation of Power Bipolar Operational Amplifiers in a Mixed Neutron and Gamma Environment

Power operational amplifiers were irradiated in a mixed neutron and gamma radiation environment. These experiments showed that the degradation of the power operational amplifiers shares a great deal of characteristics with that of the low signal devices (e.g., shift of the input offset voltage, increase of the input bias currents, and degradation of the frequency behavior). However, other phenomena were observed without equivalence in the family (linear dependence of the inverse of the quiescent current on the neutron fluence, more significant degradation of the negative output current and collapse of the primary operational amplifiers). These phenomena were explained from the special characteristics of the output stage, optimized to provide a current of several amperes. Finally, even though power devices are especially sensitive to radiation damage, some of the tested devices are suitable for radiation levels on the order of 5 ldr 10¹³ - 10¹⁴ n ldr cm^-2 in case the whole electronic system, in which the device is integrated, is carefully designed.