Research On Terahertz InP HBT Nonlinear Model And Monolithic Amplifier

Recent years,terahertz wave research has made great progress in high-speed communication,security,medical imaging,radio astronomy and national defense.It has greatly stimulated the demanding of high-performance terahertz device and component.The amplifier is the key component in terahertz systems.The amplifier’s output power,noise figure and linearity determined the operation radius,sensitivity,anti-jamming capability and communication quality of the system.The foundation of terahertz solid states amplifier are: 1)high performance device;2)accurate terahertz linear and nonlinear device model;3)circuit design method which suitable for terahertz band.For its ultra-high operation frequency,high power capablity,and high linearity properity,Indium phosphide Heterojunction bipolar transistor(InP HBT)is one of the best materials for terahertz monolithic circuit application and has become a hotspot in global terahertz solid-state devices and circuit research field.The development of terahertz InP HBT nonlinear model and amplifier is very important for the application of terahertz system.Supported by the National HighTechnology Research and Development Program("863" Program)and domestic InP HBT foundry line,this dissertation studied the terahertz on-chip measurement,the terahertz InP HBT nonlinear modeling technique and the terahertz monolithic(TMIC)design technique systematically.The research contents include:1.Researches on terahertz de-embedding method and on-wafer calibration.Aiming at the problem of how to obtain the intrinsic parameters of device-under-test(DUT)accurately in terahertz band,two kinds of test methods,off-wafer calibration + de-embedding and on-wafer calibration,are studied.First,the performances of LRRM and SOLT in terahertz band are compared and LRRM method is selected as the off-wafer calibration method for its high accuracy and robustness.According to the failure mechanism of Open-Short de-embedding method,the Open pad-Open-Through method is proposed for the terahertz band removing of test structure parasitic parameters.The characteristics of on-chip thin-film Microstrip line are studied and the frequency-dependance dielectric constant of benzocyclobutene(BCB)is modeled,and terahertz band TRL on-wafer calibration is realized.At last,the active and passive devices such as HBT,MIM capacitor are measured and three test method,Open-Short,Open pad-Open-Through,and TRL are compared.The effectiveness of Open pad-Open-Through method and TRL method is validated.A foundation is laid for further modeling work.2.Researches on terahertz model of on-chip capacitor.The traditional parameters exraction method for Line-Capacitor-Line(LCL)model is limited by the transmission line environment.A universal model extraction method based on measurement data is proposed.An analytical solution that irrelevant to transmission line structure is derived from model’s z-matrix and y-matrix.The s parameter fitting error of 7% for amplitude and 7 ° for phase in 0-66 GHz band with extracted parameter can be achieved without any finetune or optimization.A method of improving the self-resonance frequency of MIM capacitor is proposed and validated.Then the model application is extended to the terahertz band.The LCL model is validated up to 325 GHz.Based on LCL model,and the frequency response of the MIM capacitor in the terahertz band is studied.These works established the passive model library for terahertz monolithic circuit design.3.Research on InP HBT terahertz model.A RF current model is proposed for the dispersion effect caused by the heterojunction barrier structure in B-C junction of InP HBT.A dispersion bunch is added to the AgilentHBT model to improve the fitting of RF transconductance and DC transconductance.According to the HBT physical structure of HBT,the parasitic parameter distribution of the Agilent HBT model is re-planned.The parasitic inductor is split into electrode parasitic and via-hole parasitic.The magnetic coupling between the parallel electrodes and the skin effect of the metal parasitic resistance are taken into account.Based on this topology,an EM extraction method for parasitic parameter is proposed.The final model achieves a good fitting result at multiple bias points in 0.2 ~ 325 GHz band4.Development of terahertz amplifier.The design method of amplifier aimed for atmospheric window bands--140 GHz and 220 GHz--appliactions are researched.Combined with the previously established HBT nonlinear model and LCL capacitor model,a schematic design method that suitable for terahertz frequency band is proposed.First,an ultra-wideband power amplifier is designed.The measruement results show that the 3 dB bandwidth is 49.1 to 146.4 GHz covered the E-band,W-band and F-band.Average small signal gain of 11.2 dB,and saturation output power at 140 GHz 13.7 dBm with DC power consumption 125 m W.And then,a 220 GHz amplifier is designed.To exploit the maximum gain of the transistor,the simultaneously match condition is used for matching network designing.Six stages of HBT are cascaded to achieved a small signal gain of 13 dB at 220 GHz.The amplifier’s output power is 2.82 dBm at 220 GHz.Finally,eight stages amplifier with inverted-microstrip line environment is developed.The measurement presents a flat gain of more than 15 dB in 140 ~ 190 GHz band.The output power is-2.688 dBm at 210 GHz.