1. The Linearity-Efficiency Compromise
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 , July