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8 - Power Amplifiers

Published online by Cambridge University Press:  10 November 2017

Giovanni Ghione  and
Marco Pirola
Giovanni Ghione
Affiliation:
Politecnico di Torino
Marco Pirola
Affiliation:
Politecnico di Torino
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Summary

Introduction

The purpose of RF and microwave power amplifiers [1, 2, 3] is to obtain, rather than the maximum power gain, the maximum output power compatible with a given device, with acceptable efficiency and linearity. The output power of active devices is, in fact, limited by the maximum voltage and current swing, in turn related to the drain or collector breakdown voltage and to the maximum current, respectively. Moreover, while in small-signal operation the device is approximately linear, power amplifiers, while being ultimately limited by output power saturation, exhibit nonlinear effects (i.e., distortion) that become increasingly important for large input power. Nonlinearities yield signal distortion due to the generation of harmonics and intermodulation products (IMPs); such a nonlinear distortion has to be kept under control to satisfy system requirements.

Power amplifiers are traditionally divided in classes. Class A (Sec. 8.4) amplifiers are quasi-linear since, at least ideally, the device output voltage and current swings corresponding to a single-tone sinusoidal inputs are again single-tone (neglecting distortion). In class B (Sec. 8.6.1) and C (Sec. 8.6.2) amplifiers (to confine ourselves to traditional amplifier classes) the output device current swing corresponding to a sinusoidal input is a set of sine pulses; this harmonic-rich, wideband waveform is converted on the load into a narrowband one through filtering (the so-called tuned load approach).1 The rationale behind introducing strongly nonlinear amplifiers is the increase of the amplifier efficiency, i.e., the ratio between the RF output power and the power from the DC supply (Sec. 8.2.4). Typically, there is a trade-off between efficiency and distortion; in class A amplifiers, low distortion can be achieved by reducing the input and output powers, at the expense of the amplifier efficiency. In traditional amplifier classes, high efficiency can be only achieved at the expense of a large gain penalty.

More advanced amplifier classes, like the harmonic loading amplifiers (class F, Sec. 8.7.1) or the switching amplifiers (e.g., class E, Sec. 8.7.2) are able to achieve a theoretical maximum 100 percent efficiency with acceptable gain. Other strategies (like the Doherty amplifier, Sec. 8.7.3) aim at providing an acceptable efficiency also when the input signal power is not constant, but covers wide dynamics, as needed in many real-life last-generation communication systems. A final issue concerns the efficiency– linearity trade-off.

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Microwave Electronics , pp. 411 - 488
Publisher: Cambridge University Press
Print publication year: 2017

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References

[1] S., Cripps, Advanced techniques in RF power amplifier design, ser. Artech HouseMicrowave Library. Artech House, 2002.
[2] S., Cripps, RF power amplifiers for wireless communications, ser. Artech House Microwave Library. Artech House, 2006.
[3] P., Colantonio, F., Giannini, and E., Limiti, High efficiency RF and microwave solid state power amplifiers, ser. Microwave and Optical Engineering. John Wiley & Sons, 2009.
[4] S. C., Cripps, “A theory for the prediction of GaAs FET load-pull power contours,” in Microwave Symposium Digest, 1983 IEEE MTT-S International, May 1983, pp. 221–223.
[5] R. C., Dorf and J. A., Svoboda, Introduction to electric circuits. John Wiley & Sons, 2010.
[6] F. H., Raab, “Maximum efficiency and output of class-f power amplifiers,” IEEE Transactions on Microwave Theory and Techniques, vol. 49, no. 6, pp. 1162–1166, Jun. 2001.Google Scholar
[7] V., Carrubba, A. L., Clarke, M., Akmal, J., Lees, J., Benedikt, P. J., Tasker, and S. C., Cripps, “The continuous class-f mode power amplifier,” in Microwave Integrated Circuits Conference (EuMIC), 2010 European, Sep. 2010, pp. 432–435.
[8] V., Carrubba, A. L., Clarke, M., Akmal, J., Lees, J., Benedikt, P. J., Tasker, and S. C., Cripps, “On the extension of the continuous class-f mode power amplifier,” IEEE Transactions on Microwave Theory and Techniques, vol. 59, no. 5, pp. 1294–1303, May 2011.Google Scholar
[9] N. O., Sokal and A. D., Sokal, “High-efficiency tuned switching power amplifier,” Patent US 3 919 656, 1975.
[10] N. O., Sokal and A. D., Sokal, “Class E – A new class of high-efficiency tuned single-ended switching power amplifiers,” IEEE Journal of Solid-State Circuits, vol. 10, no. 3, pp. 168– 176, Jun. 1975.Google Scholar
[11] A., Grebennikov and N., Sokal, Switchmode RF power amplifiers. Elsevier, 2009.
[12] W. H., Doherty, “A new high efficiency power amplifier for modulated waves,” Proceedings of the Institute of Radio Engineers, vol. 24, no. 9, pp. 1163–1182, Sep. 1936.Google Scholar
[13] A., Grebennikov and S., Bulja, “High-efficiency Doherty power amplifiers: historical aspect and modern trends,” Proceedings of the IEEE, vol. 100, no. 12, pp. 3190–3219, Dec. 2012.Google Scholar
[14] V., Camarchia, M., Pirola, R., Quaglia, S., Jee, Y., Cho, and B., Kim, “The Doherty Power Amplifier: Review of Recent Solutions and Trends,” IEEE Transactions on Microwave Theory and Techniques, vol. 63, no. 2, pp. 559–571, Feb. 2015.Google Scholar
[15] J. M., Rubio, J., Fang, V., Camarchia, R., Quaglia, M., Pirola, and G., Ghione, “3.6-GHz wideband GaN Doherty power amplifier exploiting output compensation stages,” IEEE Transactions on Microwave Theory and Techniques, vol. 60, no. 8, pp. 2543–2548, Aug. 2012.Google Scholar
[16] R., Quaglia, V., Camarchia, T., Jiang, M., Pirola, S. D., Guerrieri, and B., Loran, “K-band GaAs MMIC Doherty power amplifier for microwave radio with optimized driver,” IEEE Transactions on Microwave Theory and Techniques, vol. 62, no. 11, pp. 2518–2525, Nov. 2014.Google Scholar
[17] L., Piazzon, P., Colantonio, F., Giannini, and R., Gioffré, “Asymmetrical Doherty power architecture with an integrated driver stage in the auxiliary branch,” International Journal of RF and Microwave Computer-Aided Engineering, vol. 24, pp. 498–507, 2014.Google Scholar
[18] N., Kumar and A., Grebennikov, Distributed power amplifiers for RF and microwave communications. Artech House, 2015.
[19] A., Katz, “Linearization: Reducing distortion in power amplifiers,” IEEE Microwave Magazine, vol. 2, no. 4, pp. 37–49, 2001.Google Scholar
[20] J., Wood, Behavioral modeling and linearization of RF power amplifiers. Artech House, 2014.
[21] N., Pothecary, Feedforward linear power amplifiers. Artech House, 1999.
[22] A., Saleh and J., Salz, “Adaptive linearization of power amplifiers in digital radio systems,” Bell System Technical Journal, vol. 62, no. 4, pp. 1019–1033, 1983.Google Scholar
[23] F. M., Ghannouchi, O., Hammi, and M., Helaoui, Behavioral modeling and predistortion of wideband wireless transmitters. John Wiley & Sons, 2015.
[24] J. L., Dawson and T. H., Lee, Feedback linearization of RF power amplifiers. Springer Science & Business Media, 2007.
[25] S. W., Chung, J. W., Holloway, and J. L., Dawson, “Open-loop digital predistortion using Cartesian feedback for adaptive RF power amplifier linearization,” in 2007 IEEE/MTT-S International Microwave Symposium. IEEE, 2007, pp. 1449–1452.
[26] C., Bremenson and D., Lombard, “Linearization of a satellite transmission channel in a time division multiple access system,” in 3rd International Conference on Digital Satellite Communications, vol. 1, 1975, pp. 144–151.Google Scholar
[27] M. S., Hashmi, Z. S., Rogojan, and F. M., Ghannouchi, “A flexible dual-inflection point RF predistortion linearizer for microwave power amplifiers,” Progress In Electromagnetics Research C, vol. 13, pp. 1–18, 2010.Google Scholar
[28] F., Ghannouchi and O., Hammi, “Behavioral modeling and predistortion,” IEEE Transactions on Microwave Theory and Techniques, vol. 10, no. 7, pp. 52–64, Dec. 2010.Google Scholar
[29] L., Sundstrom, M., Faulkner, and M., Johansson, “Quantization analysis and design of a digital predistortion linearizer for RF power amplifiers,” IEEE Transactions on Vehicular Technology, vol. 45, no. 4, pp. 707–719, 1996.Google Scholar
[30] A., Bernardini and S. De, Fina, “Analysis of different optimization criteria for IF predistortion in digital radio links with nonlinear amplifiers,” IEEE Transactions on Communications, vol. 45, no. 4, pp. 421–428, 1997.Google Scholar

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