Switch And Low-noise Amplifier Design For Terahertz Communication

In this thesis,oriented to the terahertz communication circuit,D-band single-pole double-throw switches and low-noise amplifiers are designed,which basically meet the demand.Based on electromagnetic simulation,the HEMT device model was revised to improve the accuracy of the HEMT model in the D-band.The first chapter starts from the promising applications of terahertz circuits,and conducts investigations on low-noise amplifiers and single-pole double-throw switches in the frequency band above 100 GHz.The characteristics of the first to third generation materials and the research progress of the subject at home and abroad are briefly introduced.In the second chapter,the working principle of HEMT devices and the basic theories involved in this article are introduced in detail,and the full-wave simulation software is used to establish accurate electromagnetic models of the MIM capacitors,via holes and coplanar waveguide transmission lines in the process.According to the comparison of various models,it is shown that the manufacturer's model fails in the high frequency range,and the electromagnetic simulation model is required for design.Chapter 3 mainly introduces the design of D-band single-pole double-throw switch using traveling-wave concept.The circuit adopts Ga N technology.Based on the theory of artificial transmission lines,the transmission characteristics of switches in different states is derived to select HEMT devices of appropriate size.The single-pole double-throw switch has an insertion loss of less than 7 d B in the frequency band,an isolation greater than 20 d B,and an IP_{1d B} of 24 d Bm.Chapter 4 mainly introduces the design of D-band low noise amplifier.The circuit adopts Ga As technology.After selecting the appropriate device,the minimum noise figure matching point and the highest gain matching point are obtained,and then the DC bias circuit and the matching circuit were designed.The in-band noise figure of the low noise amplifier is below 5.5 d B,and the associated gain is greater than 10 d B.In the design of active circuits in the terahertz frequency band,the accuracy of the transistor model is particularly important among many influencing factors.The high-frequency parasitic effect of terahertz devices is focused in chapter 5,and methods based on electromagnetic simulation is used for the transistor modelling.The comparison between the revised HEMT model and the manufacturer's HEMT model in the high and low frequency bands is given.And it takes the switch circuit design as an example to compare and analyse the results.Finally,it summarizes the article and puts forward the deficiencies and improvements.