Nonlinearity analysis of RF power amplified TD-SCDMA signals

In a Time Division Synchronous Code Division Multiple Access (TD-SCDMA) system, one of the critical components is the RF power amplifier. However, RF power amplifiers are perfectly linear. This is one of the main concerns in an RF power amplifier design. The nonlinearity control is described by the out-ofband power emission levels, and the nonlinearity of an RF power amplifier is described by the third-order intercept point (IP3). However, there's need of clear relationship or expression between out-ofband power emission level and IP3 for TD-SCDMA system, which helps RF designer to choose components. This paper presents the analysis of the nonlinear effect of an RF amplifier in TD-SCDMA system, and derivation of the expressions for the estimated out-of-band emission levels for TD-SCDMA signal in terms of the IP3, and the power level of the signal. The result will be helpful for RF engineers in the design and test of RF power amplifier in TD-SCDMA system.