1. Smart Power Amplifierusing variable number of constant amplitude decomposed signals--- and a dual phase modulator ---Phased array architecture for linear and efficient power amplificationusing an adaptive system of massively parallel power amplifiers2008:06:11 Magdi A. Mohamed1/30

2. Power Amplifiers Classification nonlinearity and efficiency in RF power amplifiers Type* Linearity*Efficiency* A very high very low (~50%) A/B B highlow (~78%) B/C C mediummedium (~80%) : : low high : E very lowvery high (~90%) *Linearity: for EDGE, 56 dBc at 400 KHz offset from carrier is very high *Efficiency when transistor is at full power *Type/Class E is switched-mode2008:06:11Magdi A. Mohamed2/30 3. Power Amplifiers Classification nonlinearity concerns in RF power amplifiers Linearity is defined by standard bodies: FCC, ETSI Makes sure not to affect neighboring channels Enforcing less distortion=> Less interference => Less loss of information Usually specified as Signal to Interferer Noise Ratio Linearity specification is technology dependant2008:06:11 Magdi A. Mohamed 3/30 4. Power Amplifiers Classification efficiency needs in RF power amplifiers Efficiency== Less Wasted Energy Efficiency=> Less Operational Expenses (OP-EX)=> Lower Electrical Bills=> Money Gain (+$) Efficiency=> Long Battery Life for Mobiles Efficiency=> Environmentally Friendly Inefficiency=> Heat Dissipation=> Cooling Requirements=> Noise because of Fans=> More Heat Sink=> Significantly Increased Size and Weight=> Money Loss (-$) 2008:06:11Magdi A. Mohamed4/30 5. Outphasing Power Amplifiersof Enhanced Data Rates for GSM Evolution (EDGE) Signals I 1 (t ) Ie S1 (t ) I (t )EDGE filterNonlinear Q1 (t ) Map ModulatorPAS (t )SeRF Combiner I 2 (t ) S 2 (t ) Q2 (t ) NonlinearQ(t ) EDGE filterMap ModulatorPAQe EDGE Signal Generation Modulation, amplification, and combiningreconstructs the original EDGE signal SeOutphasing means( I e , Qe ) At any point in time, Se=S1+S2,decomposing the signal vector but S1 and S2 have constantSe Se into two vectors S1 and S2radiuses. with constant amplitudesS2 The intersection of those (0,0) (vectors rotating in circles of circles defines the outphased constant radiuses)S1 signals S1 and S22008:06:11 Magdi A. Mohamed 5/30 6. Prior Art Search for RF power amplification techniquesCompeting Technologies a) Digital Pre-Distortion b) OutphasingImplementation of Outphasing 1) Lookup Tables 2) Inverse Sine & Inverse Cosine Computations 3) Complex Computation of the Square Root FunctionTypes of Decomposition A) 2-Phase Decomposition B) N-Phase Decomposition (Fixed Number of Signals = N) 2008:06:11 Magdi A. Mohamed 6/30 7. Closest Prior Art Ericsson fixed number of decomposed signalsTitle:Linear amplification system and methodsusing more than two constant length vectorsInventor: Paul Wilkinson DentAssignee: Ericsson Inc., Research Triangle Park, NC (US)Number: US 6,311,046Date: October 30, 2001Issues: fixed number of decomposed signals complex combiner hardware2008:06:11 Magdi A. Mohamed7/30 8. The New IdeaSmart Power Amplifier Concept and Computationsfor Generating Variable Number of Constant Amplitude Decomposed Signals in Real-TimeS5S5S4 S1S3 ( I e , Qe )( I e , Qe )S4 S2SeS3 S1Se S2 (0,0)(0,0)2008:06:11Magdi A. Mohamed8/30 9. The InventionSmart Power Amplifier (SPA) - Phased Array Architecture Adaptive PA ArrayS1 aS1S2 aS2S3 aS3 S aS Decomposer CombinerSi aSi PromiseSn aSnLinearity of Type A together with theEfficiency of Type EPower Amplification2008:06:11 Magdi A. Mohamed9/30 10. Demonstrations2008:06:11 Magdi A. Mohamed 10/30 11. Demonstrations2008:06:11 Magdi A. Mohamed 11/30 12. Advantages of SPA characteristics and promises1. Efficiency is not compromised for linearity as done with the conventional outphasing power amplifiers.2. By using constant amplitude signals, we completely by-pass the issues of signal distortion due to the nonlinearity of individual power amplifiers.3. Performs variable phase decomposition at the cost of two phase decomposition plus a minimal constant overhead, regardless of the number of available PAs.4. For a given design, accuracy and efficiency requirements can be met by identifying the maximum number of PAs for the proposed architecture.5. Can be used with other kinds of signals, and not just with EDGE signals.6. Selection of maximum number of PAs is performed only once for each design (EDGE, CDMA, etc.), and offline.7. Can be used in base-stations as well as in wireless handsets.8. Can be efficiently implemented as software or hardware (requires few cycles).9. Solution is transparent to receivers.2008:06:11Magdi A. Mohamed 12/30 13. Dual Phase Modulator for improved efficiency and linearity of RF power amplifiers An extremely inexpensive and novel solution for the alignment problems in Outphasing Power Amplifiers using Q-filter Techniques2008:06:11 Magdi A. Mohamed13/30 14. Problem and SolutionProblem: Outphasing is a technique used to improve RF poweramplifier efficiency without trading-off linearity.It is rarely used nowadays due to stringent branch alignmentrequirements imposed by stringent spectral requirements for digitalwireless transmission standards. Usually phase misalignment as littleas 3 degrees between the two branches can cause spectral emissionsand ACPR failures.Solution: We are proposing a new architecture where the twooutphased signals go through special DSP filtering (using nonlinearQ-filters) optimized to improve spectral content (and thus relaxing thealignment requirement up to 8 degrees or higher) without sacrificingthe desirable low Peak-To-Average Power Ratio (Crest Factor) of theoutphased signals.2008:06:11Magdi A. Mohamed14/30 15. I1 (t ) Ie Nonlinear S 1 (t ) I (t )EDGE filterQ 1 (t ) ModulatorMap PA S (t ) Se RF Combiner I 2 (t ) S 2 (t ) NonlinearQ (t ) EDGE filterQ 2 (t ) ModulatorPA QeMape.g. EDGE SignalModulation, amplification, and combining GenerationExisting Outphasing Solutionreconstructs the original EDGE signal SeAdding specially optimized DSP filtering (with nonlinear Q-filters) candramatically improve spectral content without sacrificing low Crest FactorI1 (t ) IeNonlinear S 1 (t ) I (t )EDGE filterQ 1 (t ) Optimized Modulator PA MapQ-Filter S (t ) Se RF CombinerI 2 (t ) S 2 (t )OptimizedNonlinear Q (t ) EDGE filterQ 2 (t ) Modulator PA Qe Map Q-Filter e.g. EDGE Signal Modulation, amplification, and combiningGeneration Q-filter Based Solutionreconstructs the original EDGE signal Se2008:06:11Magdi A. Mohamed 15/30 16. Spectral Contentsimproved by about 10dB, thus leading to more relaxed alignment requirements2008:06:11Magdi A. Mohamed16/30 17. Crest Factordegraded by only 0.67dB, thus still maintaining low Peak-To-Average Power Ratio (Our experiments show that using FIR linear filters does not maintain good Crest Factor, whileoptimizing the Q-filter showed good control and trading-off spectral contents versus Crest Factor)Original EDGE Outphased SignalAfter Applying OptimizedSignalBefore Q-filteringNonlinear Q-filterCF=3.5dB CF=0dB CF=0.67dB 2008:06:11Magdi A. Mohamed17/30 18. Using LinearFIR-FilterCrest Factor getsworse thanoriginal signalOutphased 1 FIR-Filtered 1Good Crest Factor Bad Crest FactorBad Spectral ContentGood Spectral ContentOutphased 2 FIR-Filtered 2Good Crest Factor Bad Crest FactorBad Spectral ContentGood Spectral Content Original SignalAmplify then Combine (e.g. EDGE)to Get Original Signal Constellation Diagrams2008:06:11Magdi A. Mohamed18/30 19. Using NonlinearQ-FilterNote that CrestFactor and SpectralContent gets betterOutphased 1 Q-Filtered 1Good Crest Factor Good Crest FactorBad Spectral ContentGood Spectral ContentOutphased 2 Q-Filtered 2Good Crest Factor Good Crest FactorBad Spectral ContentGood Spectral Content Original SignalAmplify then Combine (e.g. EDGE)to Get Original Signal Constellation Diagrams2008:06:11Magdi A. Mohamed19/30 20. Phase Misalignment Effect 10o 60o Error Vector Magnitude (EVM) = 1 2*sin(30+10/2)= 14% 3GPP Spec ~ 17% Thus, up to 10o of phase error is tolerable.2008:06:11 Magdi A. Mohamed 20/30 21. Prior ArtLinear amplification systems and methods using more than two constant length vectors:6311046, Ericsson Inc., Oct 30, 2001http://www.google.com/patents?vid=USPAT6311046&id=Q2sIAAAAEBAJ&dq=outphasing+ericssonDescribes a method to improve alignment and spectral contents, but relies on using four branches with conjugate signals,which degrades efficiency considerably and adds need to four modulators and more complex architecture.Hybrid Chireix/Doherty amplifiers and methods:6133788, Ericsson Inc., Oct 17, 2000http://www.google.com/patents?vid=USPAT6133788&id=KQcGAAAAEBAJ&dq=outphasing+ericssonDescribes a way to increase efficiency by using special combining technique, but will still suffer from traditional outphasingproblems, like branch alignment accuracy etc.Outphasing modulator:7009447, Intel Corporation, Mar 7, 2006http://www.google.com/patents?vid=USPAT7009447&id=_bJ3AAAAEBAJ&dq=outphasingDoes not describe how to solve the alignment problem. It details a method to outphase the signals, but will still suffer fromtraditional outphasing problems, like branch alignment accuracy etc.Method and apparatus to match output impedance of combined outphasing power amplifiers:7030714, Intel Corporation, Apr 18, 2006http://www.google.com/patents?vid=USPAT7030714&id=g9J3AAAAEBAJ&dq=outphasingDescribes a unique way of combining both branches to achieve maximum efficiency, but will still suffer from traditionaloutphasing problems, like branch alignment accuracy etc.RF power amplifier and methods for improving the efficiency thereof:6825719, Intel Corporation, Nov 30, 2004http://www.google.com/patents?vid=USPAT6825719&id=d9oRAAAAEBAJ&dq=outphasingDescribes a way to control the phase at the output of the PA, but will still suffer from traditional outphasing problems, likebranch alignment accuracy etc.2008:06:11 Magdi A. Mohamed21/30 22. BenefitsImprove user experience by improving battery life. It is estimated that using this technique, PA can achieve about 25% more efficiency than traditional methods.Improve cost by using much cheaper and smaller nonlinear PA operating in Class C. It is estimated that we only need half the size PA when using filtered outphasing to achieve same PA performance, besides no need to any linearity requirements on the PA thus improving yield.Eliminate need of costly outphasing alignment techniques.Shift PA performance optimization to the digital domain instead of the RF domain, giving much more controllability and ease of design, thus improving Time-To-Market.Achieve a new method that allows improving PA efficiency (and thus battery life) without compromising linearity, and have all the controls in the digital domain.Easy to implement and far superior to other outphasing or PA linearization techniques.Achieve a practical architecture for current generation wireless standards with high Crest Factor (like HSUPA), and for next generation wireless standards with high Crest Factor (like WiMAX and other OFDM standards).High Crest Factor is imposing battery life constrains and cost constrains (due to need of bigger linear PA) that can be solved by using very low Crest Factor techniques.Extendable to Smart Power Amplifiers.2008:06:11 Magdi A. Mohamed22/30 23. Backup2008:06:11Magdi A. Mohamed 23/30 24. Q-Measure ConceptFuzzy Measure AxiomsQ-Measure Extensions (2003)Let A, B X be non-intersecting sets for any choice of >-1, !=0, define: Boundary conditions:m ( ) = 0, m ( X ) = 1 (1 + f i ) 1xi A q ( A) = , -1, 0 Monotonicity:A1 A2 m ( A1 ) m ( A2 ) (1 + fxi X i ) 1 Continuity: where fi [0,1] are density generatorsguaranteed for discrete spacesConvergence Behavior of Q-MeasuresProbability Measure (1933) 1.05replaces monotonicity by additivity:1.025 p ( A U B ) = p ( A) + p ( B )Scaling Factor, fn 10.975 C as e 1C as e 2Sugeno -Measure (1975) 0.95 C as e 30.925adds one more axiom:0.9g ( A U B ) = g ( A) + g ( B ) + g ( A) g ( B ) 0.87502 4 68 10 12for a unique that satisfies g(X)=1 I te ra ti o n , n2008:06:11Magdi A. Mohamed24/30 25. Q-Measures in a nutshell X x1 x2 x3A B = X A q-measures provide A B = x6 x5 x4 more expressive and = f ( A) > 0 computationally attractive = f ( B) > 0 B=Acnonlinear models 1 x7 x8 x9 = f ( A B) = + + > 0 for uncertainty q ( A) = = q(Ac)management + + when modeling aq( B) == 1.0 0 / interdependency amongq( A) 0 plausibilityinformation sources isq( A) linear