Research On Key Cell Circuits Of Radiation Hardened Analog Integrated Circuits In Space Application

In order to meet requirements of the rapid development of space technology and aerospace industry,breaking the embargo on radiation hardened integrated circuit for aerospace applications leaded by the European and American countries,there is a urgent need to study deeply in this field.Analog integrated circuits play an important role in aerospace systems,such as power management,data converter and etc.At present,the research field of astronavigation radiation hardened integrated circuits mainly focus on radiation hardened fabrication processes and digital integrated circuits.The related researches on analog integrated circuits is not popular,especially the radiation hardened design techniques based on standard processes provided by commercial foundries.This dissertation will focus on the effect of space environment on semiconductor devices based on typical CMOS and bipolar processes,and how to improve the performance of analog integrated circuits under radiation circumstances.Finally the technologies mentioned above will be applied to radiation hardened integrated circuits of power management.This work is implemented with five sections as following.First of all,research has been made on the mechanism of the performance degradation of MOS and bipolar devices due to space radiation.The typical bipolar and MOS devices have been fabricated based on certain bipolar and MOS process,and measured under total dose experiment stresses to monitor the drift of the key parameters of the semiconductor devices.All the results can provide powerful support to the design of key radiation hardened analog unit circuits.In section 2,circuit operation principles of commonly used analog circuit(including bandgap,level shifter and oscillator)have been analyzed based on MOS processes.Effect of space environment on analog circuit is described quantitatively by means of threshold voltage shift.The improved structure of radiation hardened unit circuit has been presented.The new radiation hardened bandgap is implemented by adding a radiation-dependent current on the base of traditional circuit,which could restrain the effect of radiation on the accuracy of bandgap.From tests or simulations results,these analog circuits poccess significant anti-irradiation performance and could be used in space environment widely.In section 3,circuit operation principles of some commonly used key analog unit circuits(including bandgap,op-amp and comparator)has been analyzed based on bipolar processes.Effect of space environment on analog unit circuit is also described quantitatively though gain reduction of current,and the improved structures of key radiation hardened unit circuits have been presented.The improved radiation hardened bandgap is implemented by introducing negative feedback resistance,which could restrain the effect of the radiation on the accuracy of bandgap.The new anti-irradiation op-amp is realized by introducing?-helper current mirror,which will suppress the increase of input offset.From test or simulation results,it reveals that these key unit circuits have significant anti-irradiation performance,and could be used in space environment widely.In section 4,buck DC-DC with integrated high side switch is fabricated with MOS process..Combined with the astronavigation radiation hardened CMOS key analog unit circuit mentioned and several aspects such as implementing tolerance of total dose effect and single event effect,anti-irradiation design of DC-DC system and multiple key anti-irradiation technologies of its unit circuit have been analyzed.which make the DC-DC system achieve certain goals including input voltage range of 5.5V~17V,output adjustable range of 1.2V~12V,output current of above 5A,maximum conversion efficiency of?90%,total dose effect of?100K rad(Si)and single event effect LET of?75 Me Vcm~2/mg.Finally,all the result of tests and simulations have been proposed.In section 5,anti-irradiation PWM controller which is the key chip of high-powered DC-DC power modules has been studied.The anti-irradiation performance of its key parameters is studied based on bipolar process.Furthermore,the relationship between internal key unit circuit and the radiation hardened level of system key parameters has been investigated.Combined with the astronavigation radiation hardened bioplar key unit circuits,appropriate measures such as radiation-sensitive unit and radiation hardened design of key parameters have been carried out.Finally,the design and verification of astronavigation radiation hardened switching power supply controller have been fulfilled,which will achieve total dose effect of?100krad(Si),bandgap voltage shift after radiation of?3mV,and key parameters such as oscillation frequencies,load regulation keep almost constant without notable change.