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

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, Canada 23.05.2016 u www.spsc.tugraz.at

Motivation 2  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

Power Amplifier Circuit Model 3 Chapter Headline IEEE International Symposium on Circuits and Systems 23.05.2016

Waveform of Drain Current 4 Conduction Angle Quiescent Point Input Amplitude Saturation Angle normalized to fullscale IEEE International Symposium on Circuits and Systems 23.05.2016

Fourier Series of Drain Current 5 Linear Model Cubic Model IEEE International Symposium on Circuits and Systems 23.05.2016

Harmonics of Drain Current 6 Linear Model Cubic Model Class AB Class C Class AB Class C Class A Class B Class A Class B IEEE International Symposium on Circuits and Systems 23.05.2016

From Current to Power 7 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

Linearity and Efficiency 8 AM-AM Characteristic Instantaneous Efficiency IEEE International Symposium on Circuits and Systems 23.05.2016

Average Efficiency 9 Definition Time-Domain Ensemble-Domain IEEE International Symposium on Circuits and Systems 23.05.2016

Application Example 10 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

Matlab Code 11 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

Conclusion 12  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