Radiation effects and room-temperature annealing behaviors of bipolar operational amplifiers(op amps)of the same type but different manufacturers are investigated in this paper.It was found that the radiation effects of the same type op amps differed a lot among the manufacturers.The main reasons of the radiation-effect difference are analyzed and discussed

and radiation effects at high and low dose rates are explained.The damage enhancement fac-tor and annealing factor of the op amps are calculated

and the biggest difference of the enhancement factor among different manufacturers is about 8.