| In recent years,the application of terahertz technology in many important fields such as military confidential communication,high-resolution imaging,and high-precision nondestructive detection has attracted much attention.The high growth of terahertz system applications has greatly stimulated the demand of high-performance terahertz devices and circuits.Moreover,terahertz technology based on solid-state electronics is an important basis to realize high frequency,high integration and high reliability system,and semiconductor devices play an important role in the rapid development of terahertz solidstate technology.Among them,InP Double heterojunction bipolar transistor(InP DHBT)is the most representative: InP DHBT with excellent high frequency characteristics and power is one of the most ideal semiconductor devices in the field of solid-state terahertz technology.Due to the relatively late start of related research in China,terahertz InP DHBT technology confronts the problems of lack of advanced semiconductor technology,accurate testing technology,accurate device model and key technologies of circuits design.With the purpose of solving the key problems in the development of highperformance terahertz devices and circuits,this study investigates,tests and validates terahertz on-chip transmission line,on-chip test and calibration technology,InP DHBT modeling,terahertz monolithic integrated circuit design,monolithic integrated circuit packaging,and terahertz system application.The main research contents are presented as follows:(1)Design of terahertz InP DHBT on-chip transmission line.By adopting the distributed parameter transmission line model,the transmission characteristics of three transmission lines of thin-film microstrip line,coplanar waveguide,and grounded coplanar waveguide are explored and compared.Focusing on the problem that the substrate loss of the on-chip transmission line increases rapidly in the terahertz frequency band and the large crosstalk,a terahertz on-chip transmission line based on spoof surface plasmon polariton is designed.In terms of the spoof surface plasmon polariton transmission line,the corresponding equivalent circuit model from 0.01 to 1 THz is established.On this basis,the application of spoof surface plasmon polariton transmission line in lowering crosstalk is studied,and a spoof surface plasmon differential transmission line is designed.2)Research on terahertz on-chip test and calibration technology.In view of the problem that the on-wafer test in the terahertz frequency band is greatly affected by parasitic effects,the feasibility and effectiveness of the two calibration methods of onwafer calibration and off-wafer calibration with de-embedding applied to InP DHBT onwafer test and calibration get researched.The TRL-EMDOS on-wafer calibration method is proposed.Based on TRL otechnology,the 3D electromagnetic simulation results of the four auxiliary structures viaopen-viashort-fullopen-fullshort and the corresponding relationship of lumped elements are applied to accurately strip the interconnected through-hole and electrode metal parasitics in the InP DHBT device,further improving the calibration accuracy of on-chip test.On the basis of LRRM off-wafer calibration technology,a Double L-2L de-embedding technology is proposed,which achieves accurate stripping of the on-chip test fixture and interconnected through-hole parasitics by introducing 3D interconnected transmission line via structures(Via TL1 and Via TL2).Moreover,this method not only breaks through the limitations of traditional L-2L technology in the terahertz frequency band,but also simplifies the process of on-chip test and calibration.3)Modeling of InP DHBT device.As for the problem that the peripheral parasitic effects influence the model accuracy,a distributed InP DHBT small-signal model suitable for the terahertz frequency band is established,which divides the peripheral parasitic parameters in detail.Considering the influence of the skin effect on parasitic parameters,the 3D electromagnetic simulation method is adopted for accurately characterize and extract the parasitic effect between the interconnected through-hole and the electrodes,which optimizes the extraction process of the intrinsic parameters of the small signal model,and improves the accuracy of the small-signal model.In terms of nonlinear model research,a nonlinear model considering the device dispersion effect and self-heating effect is established to address the problem that the self-heating effect and dispersion effect of InP DHBT can affect the accuracy of model.By introducing the dispersion network,the problem of inconsistency between DC transconductance and RF transconductance is solved.The finite element thermal simulation method is used to investigate the temperature distribution of the InP DHBT.Meanwhile,the nonlinear thermal resistance of the device is extracted.4)Design of terahertz InP DHBT monolithic integrated circuit.Aiming at the problems of poor simulation accuracy and low efficiency of terahertz monolithic integrated circuit,an overall optimization simulation method is established.Using the impedance adaptive inter-stage matching technology,the problem of complex inter-stage matching circuit and large loss can be solved.Five amplifiers are designed monolithically for two important atmospheric windows(220 GHz and 300 GHz),including two 220 GHz small signal amplifiers,one 220 GHz power amplifier,and two 300 GHz power amplifiers.Among them,the small-signal gains of the two small-signal amplifiers at 220 GHz are 6d B and 8.6 d B,respectively.The 220 GHz power amplifier has a small signal gain of 12.8d B at 220 GHz,with a maximum output power of 9.8 d Bm.In addition,a gain-enhanced frequency doubling structure is proposed.A 220 GHz gain-enhanced tripler is designed.Among them,the maximum output power of the circuit at 246 GHz is-3.1 d Bm,the conversion loss is 9.6 d B,and the fundamental wave rejection is better than 15 d Bc.The gain-enhanced tripler offers a 2 d B reduction in conversion loss and a 5 d B improvement in harmonic rejection compared to a single-ended frequency multiplier.Finally,an onchip integrated dipole antenna transition structure for terahertz monolithic integrated circuit package is designed.According to the obtained test results,the insertion loss of this structure is better than 1 d B in 210-230 GHz.5)Verification of terahertz wireless communication front end system.A 16 QAM high-order digital modulation + terahertz superheterodyne wireless transceiver front-end wireless communication architecture is established.The key circuits of the terahertz transceiver front-end are studied,including the specific design methods of local oscillator chain,sub-harmonic mixer,filter,and low-noise amplifier module.In addition,experimental research on terahertz wireless communication system is carried out.Moreover,the built wireless communication system achieves indoor high-speed wireless communication at 7 m distance at 216 GHz,with a transmission rate of 45 Gbps. |
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