2000 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.

IEEE Transactions on Microwave Theory and Techniques
Volume 48 Number 6, June 2000

Table of Contents for this issue

Complete paper in PDF format

A Predistortion Linearizer Using Envelope-Feedback Technique with Simplified Carrier Cancellation Scheme for Class-A and Class-AB Power Amplifiers

Hyun-Min Park, Student Member, IEEE Dong-Hyun Baek, Student Member, IEEE Kye-Ik Jeon and Songcheol Hong Member, IEEE

Page 898.

Abstract:

A predistortion linearization method using an envelope-feedback technique is proposed and implemented in this paper. This linearizer compensates the gain and phase nonlinearity of power amplifier (PA) simultaneously by controlling both variable attenuator and phase shifter with the feedback of only the difference signal between input and output envelopes. A new carrier cancellation scheme composed of a minimization circuit, log detector, and vector modulator is also presented. This circuit achieves adaptive control of the linearizer by enabling direct measurement of out-of-band power. It is well suited to a multichannel system where the allocated channels are time variant. The principle of the proposed linearizer is described and simple AM-AM distortion analysis is presented analytically and graphically based on the conceptual schematic diagram. A two-tone test for a class-A PA at 1.855 GHz with frequency spacing of 1 MHz showed intermodulation-distortion reduction of maximum 16 dB and stable operation over 5-dB output power variation up to 4-dB backoff from the saturation power level. The proposed linearizer is also applicable to class-AB PA's without further special adjustments. The adaptation circuit is fully implemented with analog integrated circuits, which can further extend its applicability with the integration technology.

References

  1. A. N. D'Andrea, V. Lottici and R. Reggiannini, "RF power amplifier linearization through amplitude and phase predistortion", IEEE Trans. Commun., vol. 44, pp.  1477-1484, Nov.  1996.
  2. J. K. Cavers, "Amplifier linearization using a digital predistorter with fast adaptation and low memory requirements", IEEE Trans. Veh. Technol. , vol. 39, pp.  374-382, Nov.  1990.
  3. A. Bateman, R. J. Wilkinson and J. D. Marvill, "The application of digital processing to transmitter linearization", in 8th European Electrotech. Conf., 1988, pp.  64-67. 
  4. A. S. Wright and W. G. Durtler, "Experimental performance of an adaptive digital linearized power amplifier", IEEE Trans. Veh. Technol., vol. 41, pp.  395-400,  Nov.  1992.
  5. K. Yamauchi, K. Mori, M. Nakayama, Y. Mitsui and T. Takagi, "A microwave miniaturized linearizer using a parallel diode with a bias feed resistance", IEEE Trans. Microwave Theory Tech., vol. 45, pp.  2431-2435, Dec.  1997.
  6. R. C. Tupynamba and E. Camargo, "MESFET nonlinearities applied to predistortion linearizer design", in IEEE MTT-S Int. Microwave Symp. Dig., 1992, pp.  955-958. 
  7. S. P. Stapleton and F. C. Costescu, "An adaptive predistorter for a power amplifier based on adjacent channel emissions", IEEE Trans. Veh. Technol. , vol. 41, pp.  49-56, Feb.  1992.
  8. D. Wills, "A control system for a feedforward amplifier", Microwave J., pp.  22-34, Apr.  1998.
  9. S. Kang, I. Lee and K. Yoo, "Analysis and design of feedforward power amplifier", in IEEE MTT-S Int. Microwave Symp. Dig., 1997, pp.  1519-1522. 
  10. M. T. Hickson, D. K. Paul, P. Gardner and K. Konstantinou, "High efficiency feedforward linearizers", in Proc. 24th European Microwave Conf., 1994, pp.  819-824. 
  11. A. Katz, "Linearizer basics", in IEEE MTT-S Advances Amplifier Linearization Symp. Workshop, Jun. 1998.
  12. C. G. Rey, "Adaptive polar work-function predistortion", IEEE Trans. Microwave Theory Tech., vol. 47, pp.  722 -726, Jun.  1999.
  13. C. Fallesen, G. Hanington and P. M. Asbeck, "Improved linearity of a dynamic supply voltage power amplifier using digital predistortion", in IEEE Power Amplifiers for Wireless Commun. Topical Workshop, 1999, session 6.4,