Download Enzinger16 - Efficiency - Presentation

Signal Processing and Speech Communication Laboratory
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A Joint Linearity-Efficiency Model
of Radio Frequency Power Amplifiers
Harald Enzinger, Karl Freiberger, Christian Vogel
IEEE International Symposium on Circuits and Systems
Montreal, Canada
23.05.2016
u
www.spsc.tugraz.at
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Motivation
 Behavioral Model of Linearity and Efficiency
 Based on measurements
 Based on theoretical model  subject of this work
IEEE International Symposium on Circuits and Systems
23.05.2016
3
Power Amplifier Circuit Model
Chapter Headline
IEEE International Symposium on Circuits and Systems
23.05.2016
4
Waveform of Drain Current
Conduction Angle
Saturation Angle
Quiescent
Point
Input
Amplitude
normalized
to fullscale
IEEE International Symposium on Circuits and Systems
23.05.2016
5
Fourier Series of Drain Current
Linear Model
IEEE International Symposium on Circuits and Systems
23.05.2016
Cubic Model
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Harmonics of Drain Current
Linear Model
Class AB
Class A
Cubic Model
Class C
Class B
IEEE International Symposium on Circuits and Systems
23.05.2016
Class AB
Class A
Class C
Class B
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From Current to Power
Assumptions
 Ideal output matching
 Match at first harmonic
 Short at higher harmonics
 Ideal transistor output
 Zero knee voltage
 Zero output conductance
IEEE International Symposium on Circuits and Systems
23.05.2016
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Linearity and Efficiency
AM-AM Characteristic
Instantaneous Efficiency
IEEE International Symposium on Circuits and Systems
23.05.2016
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Average Efficiency
Definition
Time-Domain
Ensemble-Domain
IEEE International Symposium on Circuits and Systems
23.05.2016
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Application Example
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
IEEE International Symposium on Circuits and Systems
23.05.2016
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Matlab Code
http://www.mathworks.com/matlabcentral/fileexchange/53413
calcPaModel
PA-Model, consisting of
2 memoryless lookup-tables
calcPaSignal
demo_calcPaModel
Demo-Script for calculation of PA characteristics
demo_calcPaSignal
Demo-Script for simulation of input-output behavior
IEEE International Symposium on Circuits and Systems
23.05.2016
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Conclusion
 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
IEEE International Symposium on Circuits and Systems
23.05.2016