Design And Implementation Of High-Temperature Sensing Electronics Unit Based On GaN Devices

Sensing systems that are operable under extreme temperatures have great potentials in aerospace,down-hole,power generation,nuclear and other industries.However,the temperature limit of the first generation of silicon semiconductor electronics is only 150?,far below the desired operating temperature of modern pressure sensors.Compared with the first and second generation of semiconductor materials,the wide band-gap(WBG)semiconductor gallium nitride(GaN)materials that is as a representative of a new generation have larger bandgap and better high temperature endurance performance.The development of GaN devices have been become a research focus in semiconductor device and expand the application field of high temperature electronics.Therefore,to address this bottleneck of the embedded sensor electronics,a novel approach is proposed in this thesis by utilizing the high-temperature property of wide band-gap,especially gallium nitride(GaN)devices to replace the traditional silicon electronics.Furthermore,the another key is to challenge the limit temperature of the electronics.The emphasis on study of this thesis is in two way:the design of high-temperature device model and the solution of high-temperature sensing electronics unit.This major work completes as follows:For the establishment of high-temperature device model,firstly,the thesis gives a brief introduction to Gallium Nitride high electron mobility transistor(GaN HEMT).A full temperature dedicated measurement system has been set up,and the devices are tested from the room temperature(25?)to 300?.Furthermore,the key characteristics,including the output characteristic,transfer characteristic and self-heating effect related to temperature are studied in detail.On this basis,the DC model is improved by data fitting,the model parameters are extracted under each temperature sampling point,and the parameters are obtained as a function of temperature to get the model in the whole temperature range.Finally,the accuracy of the improved model is verified by comparing it with the measure data,and it is applied to LTSPICE to prepare for the design of the sensing electronics unit.For the circuit design of high temperature sensing electronics unit,the circuit topology of sensing electronics unit applied for high-temperature environment is studied,and the key theory and technology of each module are analyzed.At the same time,the design of the circuit board at high temperature is studied,and the selection of high-temperature devices,the selection of high-temperature circuit substrate,high-temperature circuit process and high-temperature circuit interconnection method are completed.Then,based on the high-temperature alumina ceramic substrate,through the thick film circuit fabrication process and wire bonding,the sensor electronics unit prototype for the sensor signal processing which is capable of wireless transmission at the environmental condition of 300? is successfully realized with GaN wide bandgap semiconductor devices and other high temperature resistance circuit elements.Finally,a high-temperature circuit test platform is built,and the relationship between the frequency shift and the input signal in the whole temperature range is obtained by testing the sensing unit with real-time signal analyzer.It is verified that the high-temperature device model has high matching accuracy and reliability in the wide temperature range of 25 ??300 ?.