Total Dose Radiatian Effect And Damage Mechanisms Of ADC By Different Irradiation Sources

The rapid development of computer technology, communication technology andmicroelectronics, to some extent, greatly promote the development of Analogue to DigitalConverter (ADC). ADC is a necessary module in analogue-digital mix-signal system, as keycomponent of interface of analogue facilities and digital facilities, it has been appliedextensively in Radar,satellites and other modern electronic device.Especially with the accelerating development of space technology, the demand of ADC deviceis continuingly increasing. Recent researches show that electronic devices operating in spaceenvironment is inevitably influenced by kinds of high-energy ionized particles and cosmicrays. As parts of its interface circuit, ADC is also under the effect of ionizing radiation,as aresult, the current gain of inner transistor of ADC decreases, making the accuracy alsodecrease at the same time, which may cause function failure and bring latent security disasterto satellite,space station and other spaceship.Here we choose10bit AD7910with CMOS technology and10bit AD571with Bipolartechnology as research object and study the radiation damage effect of such kind analoguemix-signal circuits under different bias and different radiation sources.Firstly, research CMOS AD7910on the radiation damage differences of different energyelectrons and different radiation sources. Results showed that: under5V bias condition, theradiation damage under1.8MeV was greater than electrons with1.0MeV; while under0V bias,electronic parameter had no obvious change. And room-temperature annealing afterirradiation showed that the radiation damage of5V bias embodied annealing effect, thoughlittle, and no post damage effect. The damage of different bias differed obviously underdifferent radiation sources(electrons and60Coγ),but damage under5V bias condition wassevere than that of0V bias condition, and with the same total dose and bias, the radiationdamage of AD7910was approximately equivalent under the two radiation sources.Secondly, in space electronic system, parts of the circuit are working, while parts are standby, ADC as one of the interface circuit, its data output port inevitably connects withsome load components. Therefore, considering resistance bias conditions helps to perfect theinfluence of bias effects. So, different bias, different dose rate, different radiation sources androom-temperature annealing experents for bipolar-technology ADC571were carried on, inorder to find out the radiation damage response of kind A-D mixed circuits under the worstbias conditions, different dose rate and different radiation sources.Results showed that: under60Co-γ ray, bipolar AD571showed not only EDLRS, butalso TDE. Under high dose rate, the damage of5V bias was much larger than resistance bias,while0V showed no change; however,under low dose rate,0V bias condition was the worst,while5V bias condition and resistance bias condition showed no obvious change. underdifferent electron energy(1.8MeV and1.0MeV) with the same bias, when irradiated to thesame total ionizing dose, the damage of bipolar AD571of high-energy electrons was muchseverer than that of low-energy electrons, and the damage quickly recovered during theroom-temperature annealing afterwar.In order to find out the influence of device encapsulation, we did electron radiationexperiment with and without lids, we found big differences between the two: the parameter ofthe former changes obviously under low total dose level, when the total dose reached3500Gy(Si), the functional parameter and performance parameter of the former failed themanual, while the latter showed no obvious change; based on experiments above, in order toresearch on radiation damage equivalence of different radiation sources, we did lid-offelectron radiation and lid-on60Co-γ radiation experiments on AD571,results showed that theradiation damage of electron radiation was much severer than that of60Co-γ radiation with thesame bias, high dose rate and total dose. What's more, under the two radiation sources, bothhad the same phenomenon,5V bias condition is the worst bias, with0V condition mostinsensitive and resistance bias in between, in addition, its room-temperature annealingshowed that: the damage of60Co-γ recovered to its initial value in short time,while that of electron radiation recovered in some way but slow, and no post damage effect was found.At last, combined with scientific experiment means and data analysis methods,try toinvestigate the cause of the degradation of radiation sensitive parameters of such kind ADC,and analyzed its damage mechanism under different bias and radiation source. It can suppliestheory basis and experiment support for improving the performance of such kind analoguemix-signal circuits.