Conclusion

Abstract

The emphasis on higher data-rates has driven the industry towards linear modulation techniques such as QPSK, QAM and multi-carrier configurations. Spectral efficiency has become a significant factor in the use of such linear modulation techniques. The result is a signal with a fluctuating envelope which generates intermodulation distortion from the power amplifiers. Linear modulation techniques are more spectral efficient however requires a linear power amplifier. Broadband power amplifiers are important RF components in a wireless communications system. All power amplifiers exhibit inherent nonlinearity which causes spectral regrowth in systems using non-constant envelope digital modulation schemes. The main source of spectral regrowth is the intermodulation distortion of the modulated carrier by nonlinearities in the transmitter power amplifier. Requirements for suppression of spectral regrowth have become more stringent and the improvement in spectral regrowth suppression is the primary reason for using power amplifier linearization techniques.