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 A Mirror Predistortion Linear Power Amplifier

Khaled Fayed 2/29 Presentation Outline  Introduction  Linearization Techniques  Mirror Predistortion Technique –What is it? –Implementation –Results  Conclusion

Khaled Fayed 3/29 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

Khaled Fayed 4/29 Introduction (Cont…)  Power: 1 dB Compression Point (P1dB)  Efficiency:  Linearity:

Khaled Fayed 5/29 Introduction (Cont…)  PA Linearity Characterization: AM-AM & AM-PM curves x i/p P1dB 1 dB

Khaled Fayed 6/29 Linearization Techniques  Three Major Categories –Feedback –Feedforward –Predistortion

Khaled Fayed 7/29 Linearization Techniques (Cont…)  Predistortion

Khaled Fayed 8/29 Linearization Techniques (Cont…)  Predistortion (Diode PD)

Khaled Fayed 9/29 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

Khaled Fayed 10/29 Linearization Techniques (Cont…)  Predistortion (Cubic PD)

Khaled Fayed 11/29 Linearization Techniques (Cont…)  Predistortion (Cubic PD)

Khaled Fayed 12/29 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

Khaled Fayed 13/29 Linearization Techniques (Cont…)  Predistortion (Modified Cubic PD) –Use one more CPD to cancel IM5 independently

Khaled Fayed 14/29 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

Khaled Fayed 15/29 Mirror PD Linearization (Cont…)

Khaled Fayed 16/29 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)

Khaled Fayed 17/29 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%

Khaled Fayed 18/29 Mirror PD Linearization (Cont…)  Implementation (Hybrid Module) AMCOM Part # AM AMCOM Part # AM304031

Khaled Fayed 19/29 Mirror PD Linearization (Cont…)  Hybrid Module (Picture)

Khaled Fayed 20/29 Mirror PD Linearization (Cont…)  Hybrid Module (Test Setup)

Khaled Fayed 21/29 Mirror PD Linearization (Cont…)  Hybrid Module (Test Setup Picture)

Khaled Fayed 22/29 Mirror PD Linearization (Cont…)  Hybrid Module Results (IMD3 vs. Pout) 23 dB 5 dB

Khaled Fayed 23/29 Mirror PD Linearization (Cont…)  Hybrid Module Results (IMD5 vs. Pout) 5 dB

Khaled Fayed 24/29 Mirror PD Linearization (Cont…)  Hybrid Module Results (Efficiency vs. IMD3) 4.5 times

Khaled Fayed 25/29 Mirror PD Linearization (Cont…)  Hybrid Module Results (Bandwidth)

Khaled Fayed 26/29 Mirror PD Linearization (Cont…)  Hybrid Module Results (Temperature)

Khaled Fayed 27/29 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

Khaled Fayed 28/29 Conclusion (Cont…)  Results Summary –IMD3 improved by dB BO –IMD3 improved by dB BO –IMD5 improved by dB BO –Efficiency Improved four IMD3 of -60 dBc –BW > 20 MHz  Sufficient for WiMax channel

Khaled Fayed 29/29 Questions?