With continued pressure for increased 3G coverage for smart phones, increased Internet connection for Wi-Fi and WiMAX, and the imminent introduction of 4G/LTE systems, design activity for digital communication RF components has never been greater. At the forefront of the design activity is the development of power amplifiers (PA). And at the top of the list of concerns for PA design engineers is power added efficiency (PAE). High PAE in a power amplifier provides:
• increased battery life for mobile device users.
• maximum antenna coverage for base stations and lower electricity bills for network providers.
• the opportunity for manufacturers to demand higher prices for higher performing devices and consequently, higher revenue return per wafer.
Digital modulation schemes such as PSK and QAM (used in 3G systems such as WCDMA and EV-DO) and OFDM (used in WiMAX and 4G systems such as LTE) result in modulated RF carriers with high Peak-to-Average Ratios (PAR). The PA design engineer must take into account the consequences of amplifying a communication signal with high PAR yet still maintain linearity and acceptable Error Vector Magnitude (EVM) rates. A linear vector network analyzer (VNA) provides essential information regarding the performance of small signal amplifiers operating under linear conditions. However, when high power amplifiers are designed for compressed nonlinear operation, the VNA must provide additional information to help the engineer optimize the design. The VectorStar™ Nonlinear VNA provides the essential information necessary to develop optimized nonlinear devices.