| Linear regulators are named for its pass element working in linear workspace.Duing to the voltage regulation performance is good, output ripple voltage is small,and application circuit is simple, linear regulators are widely used in space electronicssystem. The devices worked in space environment are inevitably affected by spaceradiation, and may be functional failure. So the purpose of my topic is that test andanalysis the ionization irradiation resistance of the linear integrated voltage regulator,and research failure mode, failure mechanism and reinforcement design of total doseeffect on the linear regulator.1. Delve into the working principle and working parameters of linear integratedvoltage regulator, and the electrical characteristics of the research device is mastered.Total dose effect of bipolar circuits is made a thorough research, including formationmechanism and increasing mechanism of oxide trap charge and interface trap charge.2. Reference to military specifications, the ionization irradiation experiment isdesigned, while ionizing radiation response and annealing characteristics the domesticlinear regulator JW117are studied. Experimental results show that:(1) The ionizingradiation resistance of domestic regulator JW117is very poor, and total dose failurethreshold is very low. Reference voltage, voltage regulation, current regulation, andthe ripple suppression ratio are sensitive parameters to ionizing radiation, whichdegradation is very obvious in ionizing radiation environment.(2) The degradation ofreference voltage is caused by degradation of current gain in internal transistor,andthe two NPN transistor is the most critical, while the two LPNP transistor also playsan important role. Voltage regulation is affected by the common mode rejection ratioand power supply rejection ratio of error amplifier. Current regulation and ripplesuppression ratio was mainly affected by the open loop gain of the error amplifier.Reference voltage source and the error amplifier is the key module, which are focalpoint to consider when we take the radiation resistance reinforcement design.(3)Thefailure mechanism of total dose effect on linear rugultor: oxide trap charge andinterface trap charge will be induced in the ionizing irradiation. Both of them lead todegradation of current gain internal bipolar transistors of linear voltage regulator, andthen make the internal important modules such as voltage reference circuit,, erroroperational amplifiers, and power pass element of voltage regulator dagradation. finally, it will make the reference voltage, voltage regulation, current regulation, andthe ripple suppression of the voltage regulator dagradation, which will lead functionof the voltage regulator to failure.3. With the aid of PSPICE, by means of simulation damage loss of sensitiveparameters of voltage regulator as current gain drop. We finish the simulation analysisof total dose effect on linear voltage regulator. the simulation results are comparedwith the test results, which further verifies the failure mode and failure mechanism ofthe total dose effect on voltage regulator.4. Based on the master failure mode and failure mechanism of regulator, thedomestic linear voltage regulator JW117is made twice reinforcement design test:(1)using the “thinning note before boron oxide layer thickness, and deepen deepth of theemitter junction”, current gain redundancy of internal transistor is increasing by themethod, which strengthen design of voltage regulator.(2) The passivation technologyof voltage regulator is changed from "mixed chlorine oxidation and PE passivation" to"mix chlorine oxidation and BPSG passivation", which finished reinforcement designof voltage regulator. Finally a practical and effective reinforcement measures is found,namely “mixed chlorine oxidation and BPSG passivation” of passivation layerreinforcement technology. The failure threshold total dose of homemade linearvoltage regulator is increased from100Gy(Si) to1000Gy(Si). |
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