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A Mirror Predistortion Linear Power Amplifier

A Mirror Predistortion Linear Power Amplifier. Presented By: Khaled Fayed 1 Co-Authors: Amir Zaghloul 2,3 , Amin Ezzeddine 1 , and Ho Huang 1 1. AMCOM Communications Inc., Gaithersburg, MD 2. Virginia Polytechnic Institute & State University 3. U.S. Army Research Laboratory .

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A Mirror Predistortion Linear Power Amplifier

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  1. A Mirror Predistortion Linear Power Amplifier Presented By: Khaled Fayed1 Co-Authors: Amir Zaghloul2,3 , Amin Ezzeddine1, and Ho Huang1 1. AMCOM Communications Inc., Gaithersburg, MD 2. Virginia Polytechnic Institute & State University 3. U.S. Army Research Laboratory

  2. Presentation Outline • Introduction • Linearization Techniques • Mirror Predistortion Technique • What is it? • Implementation • Results • Conclusion

  3. Introduction • PA is the most Power Hungry component in wireless communication systems • WiMax, LTE and other new technologies use high data rates:  Need higher linearity  BO not recommended where Efficiency will suffer • Solution? Use Linearization Techniques

  4. Introduction (Cont…) • Power: 1 dB Compression Point (P1dB) • Efficiency: • Linearity:

  5. 1 dB i/p P1dB x Introduction (Cont…) • PA Linearity Characterization: AM-AM & AM-PM curves

  6. Linearization Techniques • Three Major Categories • Feedback • Feedforward • Predistortion

  7. Linearization Techniques (Cont…) • Predistortion

  8. Linearization Techniques (Cont…) • Predistortion (Diode PD)

  9. Linearization Techniques (Cont…) • Predistortion (Diode PD) • Advantages • Simple • Easy to be integrated with PA in a Chip • Disadvantages • Very limited linearization • No tracking with Power or Temperature • Requires Measurement of both PD and PA nonlinear performance

  10. Linearization Techniques (Cont…) • Predistortion (Cubic PD)

  11. Linearization Techniques (Cont…) • Predistortion (Cubic PD)

  12. Linearization Techniques (Cont…) • Predistortion (Cubic PD) • Advantages • Relatively simple • Very good improvement in IMD3 reported (>20dB) • Disadvantages • IMD5 and higher degrades • Vulnerable to Process & Temp variations • No power tracking

  13. Linearization Techniques (Cont…) • Predistortion (Modified Cubic PD) • Use one more CPD to cancel IM5 independently

  14. Mirror PD Linearization • What is Mirror PD? • A new Linearization Technique! • Mitigates deficiencies of both Feedforward & PD by using a PD that uses a smaller copy or mirror of the main PA • This mirror feeds out of phase IM’s to PA input to get IM free output

  15. Mirror PD Linearization (Cont…)

  16. Mirror PD Linearization (Cont…) • This leads to improvement in both IMD3 and IMD5 with: • Higher Efficiency than Feedforward (Note that EA output power and gain requirements are reduced by the gain of the main PA) • Generally has better power and temperature tracking than other PD technique (The mirror tracks the main PA)

  17. Mirror PD Linearization (Cont…) • The copy is realized by using multiple cells of the mirror PA to build the main PA • For the shown case Power overhead is 25%

  18. Mirror PD Linearization (Cont…) • Implementation (Hybrid Module) AMCOM Part # AM204437 AMCOM Part # AM304031

  19. Mirror PD Linearization (Cont…) • Hybrid Module (Picture)

  20. Mirror PD Linearization (Cont…) • Hybrid Module (Test Setup)

  21. Mirror PD Linearization (Cont…) • Hybrid Module (Test Setup Picture)

  22. Mirror PD Linearization (Cont…) • Hybrid Module Results (IMD3 vs. Pout) 5 dB 23 dB

  23. Mirror PD Linearization (Cont…) • Hybrid Module Results (IMD5 vs. Pout) 5 dB

  24. Mirror PD Linearization (Cont…) • Hybrid Module Results (Efficiency vs. IMD3) 4.5 times

  25. Mirror PD Linearization (Cont…) • Hybrid Module Results (Bandwidth)

  26. Mirror PD Linearization (Cont…) • Hybrid Module Results (Temperature)

  27. Conclusion • A new Linearization technique “Mirror PD” was presented • A Hybrid module was built with a P1dB of 41.5 dBm at 3.5 GHz

  28. Conclusion (Cont…) • Results Summary • IMD3 improved by 23 dB @ 7.5 dB BO • IMD3 improved by 5 dB @ 3.5 dB BO • IMD5 improved by 5 dB @ 8.5 dB BO • Efficiency Improved four times @ IMD3 of -60 dBc • BW > 20 MHz  Sufficient for WiMax channel

  29. Questions? khaled@amcomusa.com

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