A Mirror Predistortion Linear Power Amplifier

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