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The Linearity-Efficiency Compromise

The Linearity-Efficiency Compromise. Presenter :Yu-Cheng Cheng. Outline. Energy Balance in an RF Power Amplifier Feed-Forward and Feedback Linearizers Dynamic Load Modulation LINC and Doherty Architectures Envelope Tracking in Current-Mode Pas Conclusion.

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The Linearity-Efficiency Compromise

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  1. The Linearity-EfficiencyCompromise Presenter :Yu-Cheng Cheng

  2. Outline • Energy Balance in an RF Power Amplifier • Feed-Forward and Feedback Linearizers • Dynamic Load Modulation LINC and Doherty Architectures • Envelope Tracking in Current-Mode Pas • Conclusion

  3. Energy Balance in an RF Power Amplifier Figure 1. Power relationships in a general electronic amplifier, diagram of a linear class A or class B RF power amplifier. 資料來源:IEEE期刊Microwave Magazine vol. 11, “THE LINEARITY-EFFICIENCY Compromise”, P45

  4. Energy Balance in an RF Power Amplifier • it must provide a signal gain, G, given by • The amplifier’s power added efficiency can beobtained from 資料來源:IEEE期刊Microwave Magazine vol. 11, “THE LINEARITY-EFFICIENCY Compromise”, P45

  5. Energy Balance in an RF Power Amplifier Figure 2. Illustrative (a) input and (b) output I/V characteristics of the active device shown in Figure 1. 資料來源:IEEE期刊Microwave Magazine vol. 11, “THE LINEARITY-EFFICIENCY Compromise”, P46

  6. Energy Balance in an RF Power Amplifier Figure 3. (a) Ideal linear and optimized class A and B efficiencies as a function of normalized input voltage amplitude. (b) Normalized input and output spectra of the optimizedclass B amplifier with an output adjacent channel power ratio of 45 dBc 資料來源:IEEE期刊Microwave Magazine vol. 11, “THE LINEARITY-EFFICIENCY Compromise”, P46

  7. Feed-Forward and Feedback Linearizers Figure 4. Demonstration of the linearization of the power amplifier (PA) system of its exact predistorter (PD). 資料來源:IEEE期刊Microwave Magazine vol. 11, “THE LINEARITY-EFFICIENCY Compromise”, P49

  8. Feed-Forward and Feedback Linearizers Figure 5. Diagram of the basic structure of the feedforward linearizer showing the main signal path on the top. 資料來源:IEEE期刊Microwave Magazine vol. 11, “THE LINEARITY-EFFICIENCY Compromise”, P49

  9. Dynamic Load Modulation LINC and Doherty Architectures Figure 6. Simplified functional diagram of the linear amplification with nonlinear components. 資料來源:IEEE期刊Microwave Magazine vol. 11, “THE LINEARITY-EFFICIENCY Compromise”, P50

  10. Dynamic Load Modulation LINC and Doherty Architectures Figure 7. (a) Functional diagram of the basic Doherty arrangement showing the input 90º power divider, (b) Output power contributions of the carrier and peaking amplifiers for optimized efficiency and linear operation. 資料來源:IEEE期刊Microwave Magazine vol. 11, “THE LINEARITY-EFFICIENCY Compromise”, P51

  11. Envelope Tracking in Current-Mode PAs Figure 8.Block diagram of a fully analog envelope tracking system showing the dynamic bias modulator that supplies the RF current-mode power amplifier with the dc power needed to minimize dissipation. 資料來源:IEEE期刊Microwave Magazine vol. 11, “THE LINEARITY-EFFICIENCY Compromise”, P53

  12. Conclusion • Wireless transmitter builds systems that are more efficient in terms of both power supply and wireless spectrum allocation usage.

  13. References [1] Lavrador, P.M., Cunha, T.R., Cabral, P.M., Pedro, J.C., “THE LINEARITY-EFFICIENCY Compromise”, IEEE Trans. Microwave Magazine vol. 11, pp. 44-58, July. 2010.

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