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The effect of baseband impedance termination on the linearity of GaN HEMTs

Research output: Chapter in Book/Report/Conference proceedingConference contribution

  • M Akmal
  • J Lees
  • S Woodington
  • V Carrubba
  • S Cripps
  • J Benedikt
  • KA Morris
  • MA Beach
  • JP McGeehan
  • P Tasker
Original languageEnglish
Title of host publicationEuropean Microwave Conference 2010 (EuMC), Paris, France
Publisher or commissioning bodyInstitute of Electrical and Electronics Engineers (IEEE)
Pages1046 - 1049
Number of pages4
ISBN (Print)9781424472321
StatePublished - Sep 2010
Event40th European Microwave Conference (EuMC) - Paris, France


Conference40th European Microwave Conference (EuMC)
Period1/09/10 → …


This paper demonstrates the significant effect of baseband impedance termination on the linearity performance of a 10W GaN HEMT device driven to deliver a peak envelope power of approximately 40dBm. The paper also proposes a further refinement to a state-of-art active IF load-pull measurement system to allow the precise independent control of all significant baseband components generated as a result of the multi-tone excitation used. The presentation of specific baseband impedances has delivered a 20dBc and 17dBc improvement in IM3 and IM5 inter-modulation products respectively, relative to the case of a classical, ideal short circuit. As expected for this device, this was achieved by emulating appropriate negative impedances lying outside of the Smith chart, and when this observation is considered alongside the Envelope Tracking PA architecture, this raises the interesting possibility of significantly improving PA linearity using the very mechanisms that are employed to improve PA efficiency.

Additional information

Rose publication type: Conference contribution Sponsorship: This work has been carried out as part of EPSRC grant EP/F033702/1. The authors would also like to thank CREE for supporting this activity and supplying the devices Terms of use: Copyright © 2010 IEEE. Reprinted from 2010 European Microwave Conference (EuMC). This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of the University of Bristol's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to By choosing to view this document, you agree to all provisions of the copyright laws protecting it.

Research areas

  • GaN HEMTs


40th European Microwave Conference (EuMC)

Duration1 Sep 2010 → …

Event: Conference

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