UNIVERSITYofCALIFORNIA SantaBarbara MMIC Power AmplifiersinGaNHEMT andInP HBTTechnologies A dissertationsubmittedinpartialsatisfactionofthe requirementsforthe degreeof DoctorofPhilosophy in Electricaland ComputerEngineering by Vamsi K. Paidi Committeeincharge: ProfessorMarkRodwell, Chair ProfessorSteveLong ProfessorUmeshMishra ProfessorRobertYork September2004 The dissertationofVamsi K. Paidiisapproved: Chair July2004 MMIC Power AmplifiersinGaNHEMT andInP HBTTechnologies Copyright2004 by Vamsi K. Paidi iii Acknowledgements wouldliketothankProf. Rodwellforhisguidanceandconstantencouragement. I I would also like to thank Prof. Long and Prof. Mishra for their timely advice and consideration. This work would not have been possible without the help from Prof. Rodwell’sgroup,Prof. Mishra’sgroup,Prof. Long’sgroupandthecleanroom staff. iv Curriculum Vitæ Vamsi K. Paidi EDUCATION B. Tech, IndianInstituteofTechnology,Madras, India,June 2000 M. S,Ph. DinElectricalandComputerEngineeringUniversityofCalifornia,Santa Barbara, September2004. PROFESSIONALEMPLOYMENT 2000 - 2004 Research assistant, Department of Electrical and Computer Engineer- ing, UniversityofCalifornia,SantaBarbara PUBLICATIONS V.Paidi,Z.Griffith,Y.Wei,M.Dahlstrom,M. Urteaga,N. Parthasarathy,M. Seo, L. Samoska, A. Fung and M. J. W. Rodwell, “G-band (140-220-GHz) and W- band (75-110-GHz) InP DHBT power amplifiers”, submitted to IEEE transactions onMicrowave TheoryandTechniques, 2004. V. Paidi, Z. Griffith, Y. Wei, M. Dahlstrom, M. Urteaga, L. Samoska, A. Fung and M. J. W. Rodwell, “Common base amplifier with 7-dB gain at 176 GHz v in InP DHBT technology”, IEEE Radio Frequency Integrated Circuits Symposium, Fortworth,Texas, June2004. V. Paidi, S. Xie, R. Coffie, U. K. Mishra,S. Long and M. J. W. Rodwell, “Sim- ulations of high linearity and high efficiency of Class B power amplifiers in GaN HEMT technology”,Lester Eastman Conference, Newark,DE, Aug2002. V. Paidi, S. Xie, R. Coffie, B. Moran, S. Heikman, S. Keller, A. Chini, S. P. Denbaars, U. K. Mishra,S. Long and M. J. W. Rodwell, “High linearity and high efficiency of Class B power amplifiers in GaN HEMT technology”, IEEE transactions onMicrowave TheoryandTechniques, Vol. 51, No. 2, Feb2003. S. Xie, V. Paidi, R. Coffie, S. Keller, S. Heikman, B. Moran, A. Chini, S. P. DenBaars, U. K. Mishra, S. Long, M. J. W. Rodwell “High linearity Class B amplifiersinGaNHEMT Technology”,IEEEMicrowave andWireless Components Letters, 2002. Y.Wei,M. Urteaga,Z. Griffith,D. Scott,S. Xie,V.Paidi,N.Parthasarathy,M. J. W. Rodwell“75GHz,80mWInPDHBTpoweramplifier”,IEEERadioFrequency IntegratedCircuits Symposium, pp. 919-921,Philadelphia,PA, June 2003. Y.Wei, S. Krishnan, M. Urteaga, Z. Griffith,D. Scott,V. Paidi,N. Parthasarathy, vi M. J. W. Rodwell “40 GHz MMIC Power amplfiers in InP DHBT Technol- ogy”, IEEE Lester Eastman Conference on High Performance Devices, Newark, Delaware,August 2002. vii Abstract MMIC PowerAmplifiersinGaNHEMT andInPHBT Technologies by Vamsi K. Paidi Key components in any wireless communication system are the high frequency power amplifiers that must meet strict performance specifications regarding power gain, outputpower,linearityandpoweradded efficiency(PAE).Class A poweram- plifiershavehighlinearity,butexhibitPAE wellbelow50%. Improvedefficiencyis obtained with switched-mode circuits. These, unfortunately, show high distortion. Push-pullclassBamplifiersofferthepotentialforimprovedefficiency,atatheoreti- callimitof78.6%,combinedwithdistortionaslowasclass A.Foroperationinsub- octave bandwidths, a classical push-pull class B can be replaced by a single-ended class B amplifier with an output bandpass or lowpass filter. The high breakdown voltage (>50 V) and 50 GHz current gain cutoff frequency f of an AlGaN/GaN τ high electron mobility transistors (HEMT) result in record power densities (>12.1 W/mm) in the 7-10-GHz frequency band. A common-source class B circuit fabri- viii cated in this technology demonstrated 4 W maximum saturated output power at 8 GHz with 13-dB powergain. High linearity, >35-dBcintermodulationsuppression under two-tone operation and high PAE of 34% has been achieved under class B operation. The second phase of research involved developing 75-220-GHz power ampli- fiers which have applications in wide-band communication systems, atmospheric sensing and automotive radar. Modern InP double heterojunction bipolar transis- tors(DHBTs)simultaneouslyexhibit6VV ,400GHzf ,3.5mA/µm2 collector br max currentdensityandhighthermalconductivity,resultinginhighpowerdensityinthe 75-220-GHzfrequencyband. Thecommon-basetopologyexhibitshighermaximum stable gain in this band when compared to common-emitter and common-collector topologies. Layout parasitics including base inductance, L and collector to emit- b ter overlap capacitance, C can cause instability. A single-sided collector contact ce has been employedto reduce C . A single-stage common-basetuned amplifierex- ce hibited 7-dB small-signal gain at 176 GHz. This amplifier demonstrated 8.77 dBm output power with 5-dB associated power gain at 172 GHz. A two-stage common- base amplifierexhibited8.1 dBmoutputpowerwith6.35-dBassociated powergain at 176 GHz and demonstrated 9.13 dBm of saturated output power. This two-stage ix common-baseamplifierexhibited10.3 dBmoutputpowerat150.2 GHz. x