| Power amplifiers are key components in wireless transceivers. Their function is to amplify the signal and generate the required RF power that allows transmission of the signal over the appropriate range. Linear power amplifiers are needed in many modern wireless systems that deploy non-constant envelope modulations. Examples of such modulations are seen in CDMA and OFDM systems.; A common disadvantage of linear power amplifiers compared to their nonlinear counterparts is their substantially lower power efficiency. Since the power amplifier is the component that consumes most of the power in a transmitter, this lower power efficiency directly translates into lower talk time in portable systems. Therefore, improving efficiency of linear power amplifiers is a major objective. Finding fast and systematic nonlinearity analysis methods and tools as well as linearization techniques that promise higher efficiency are among the major challenges along this way. An additional challenging requirement in portable systems is the need for smaller and lower cost power amplifier devices. This work addresses these challenges and provides improved methods, techniques and devices. A fast adjacent channel power ratio (ACPR) simulation method and software are provided as a very effective tool for simulation of nonlinearities. High efficiency linearization techniques including pulse deletion modulation (PDM), pulse width modulation (PWM), pulse width and amplitude modulation (PW&AM) and nonlinear cascading are analyzed. Some issues related to power amplifier modules are discussed. |
