1st International Workshop on Energy Efficient and Reconfigurable Transceivers

Research Article

Optimum Design of Doherty RFPA for Mobile WiMAX Base Stations

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  • @INPROCEEDINGS{10.1007/978-3-642-35155-6_59,
        author={Abubakar Hussaini and Tahereh Sadeghpour and Raed Abd-Alhameed and Mark Child and Nazar Ali and Jonathan Rodriguez},
        title={Optimum Design of Doherty RFPA for Mobile WiMAX Base Stations},
        proceedings={1st International Workshop on Energy Efficient and Reconfigurable Transceivers},
        proceedings_a={EERT},
        year={2012},
        month={12},
        keywords={Doherty RFPA linearity digital pre-distortion OFDM},
        doi={10.1007/978-3-642-35155-6_59}
    }
    
  • Abubakar Hussaini
    Tahereh Sadeghpour
    Raed Abd-Alhameed
    Mark Child
    Nazar Ali
    Jonathan Rodriguez
    Year: 2012
    Optimum Design of Doherty RFPA for Mobile WiMAX Base Stations
    EERT
    Springer
    DOI: 10.1007/978-3-642-35155-6_59
Abubakar Hussaini1,*, Tahereh Sadeghpour2,*, Raed Abd-Alhameed2,*, Mark Child2,*, Nazar Ali3,*, Jonathan Rodriguez1,*
  • 1: Instituto de Telecomunicações
  • 2: University of Bradford
  • 3: Khalifa University
*Contact email: ash@av.it.pt, tsadeghp@bradford.ac.uk, r.a.a.abd@bradford.ac.uk, m.b.child@bradford.ac.uk, ntali@kustar.ac.ae, jonathan@av.it.pt

Abstract

RF power amplifiers in mobile WiMAX transceivers operate in an inherently nonlinear manner. It is possible to amplify the signal in the linear region, and avoid distortion, using output power back-off; however, this approach may suffer significant reduction in efficiency and power output. This paper investigates the use of Doherty techniques instead of back-off, to simultaneously achieve good efficiency and acceptable linearity. A 3.5 GHz Doherty RFPA has been designed and optimized using a large signal model simulation of the active device, and performance analysis under different drive levels. However, the Doherty EVM is generally poor for mobile WiMAX. Linearity may be improved by further digital pre-distortion, and a simple pre-distortion method using forward and reverse AM-AM and AM-PM modeling. Measurements on the realized amplifier show that this approach satisfies the EVM requirements for WiMAX base stations. It exhibits a PAE over 60%, and increases the maximum linear output power to 43 dB, whilst improving the EVM.