A Joint Linearity-Efficiency Model of Radio Frequency Power - - PowerPoint PPT Presentation

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A Joint Linearity-Efficiency Model of Radio Frequency Power - - PowerPoint PPT Presentation

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Signal Processing and Speech Communication Laboratory 1 A Joint Linearity-Efficiency Model of Radio Frequency Power Amplifiers Harald Enzinger, Karl Freiberger, Christian Vogel IEEE International Symposium on Circuits and Systems Montreal,

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u www.spsc.tugraz.at

Signal Processing and Speech Communication Laboratory

A Joint Linearity-Efficiency Model

  • f Radio Frequency Power Amplifiers

23.05.2016 IEEE International Symposium on Circuits and Systems

1

Harald Enzinger, Karl Freiberger, Christian Vogel Montreal, Canada

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Motivation

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  • Behavioral Model of Linearity and Efficiency
  • Based on measurements
  • Based on theoretical model  subject of this work
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Power Amplifier Circuit Model

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Chapter Headline

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Waveform of Drain Current

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Conduction Angle Saturation Angle Input Amplitude Quiescent Point normalized to fullscale

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Fourier Series of Drain Current

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Cubic Model Linear Model

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Harmonics of Drain Current

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Class A Class B Class AB Class C Class A Class B Class AB Class C

Cubic Model Linear Model

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From Current to Power

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Assumptions

  • Ideal output matching
  • Match at first harmonic
  • Short at higher harmonics
  • Ideal transistor output
  • Zero knee voltage
  • Zero output conductance
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Linearity and Efficiency

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AM-AM Characteristic Instantaneous Efficiency

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Average Efficiency

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Definition Time-Domain Ensemble-Domain

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Application Example

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Setup

  • Class AB model
  • Various signals
  • With / without DPD

Observations

  • Average efficiency is

mainly defined by required backoff

  • With DPD, the backoff

can be reduced

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Matlab Code

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http://www.mathworks.com/matlabcentral/fileexchange/53413 calcPaModel calcPaSignal demo_calcPaSignal demo_calcPaModel PA-Model, consisting of 2 memoryless lookup-tables Demo-Script for calculation of PA characteristics Demo-Script for simulation of input-output behavior

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Conclusion

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  • Theoretical Model of Linearity and Efficiency
  • Includes strong nonlinearity due to current clipping
  • Includes weak nonlinearity due to transconductance variation
  • Does not include nonlinear memory effects
  • Potential Applications
  • High-level system simulations
  • Study of new transmitter architectures
  • Education