Linear Rf Power Amplifier Design for Cdma Signals : a Spectrum

In recent years, CDMA has been recognized as one of the most efficient and reliable schemes for cellular radio communications. The CDMA scheme was adopted as a new wireless communication industry standard, IS-95,1 by the Electronic Industries Association (EIA) and the Telecommunications Industry Association (TIA) in 1993 and possesses several distinct advantages:2 The spectral density is reduced and the RF resource is used more efficiently. Protection against co-channel interference is provided, which makes it possible to reduce the frequency reuse factor to 1. High communication security is also provided. Multipath effects are reduced significantly and channel manipulation and hand-over procedures are simplified greatly. Many CDMA cellular networks are being deployed rapidly in the US and other countries. As in other communication systems, one of the critical and costly components in a CDMA system is the RF power amplifier. One of the main concerns in such an RF power amplifier design is the nonlinear effect of the amplifier. The nonlinearity of an RF amplifier can degrade the quality of the CDMA signal, increasing bit error rate and interference to adjacent channels. As part of the IS-95 standard, EIA/TIA has set requirements for the control of the nonlinearity of RF amplifiers used in cellular CDMA systems. The nonlinearity control is specified by the out-of-band power emission levels.1 Out-of-band emission is also called spectrum regrowth. A typical illustration of spectrum regrowth through an LINEAR RF POWER AMPLIFIER DESIGN FOR CDMA SIGNALS: A SPECTRUM ANALYSIS APPROACH