Recent improvements in semiconductor technology, such as laterally diffused metal oxide semiconductor (LDMOS) and gallium nitride high electron mobility transistors (GaN-HEMT), are empowering researchers to develop high-performance microwave circuits and systems. When operated in their nonlinear regions and properly terminated, these devices result in high-effi ciency power amplifi ers (PA).  Such developments underscore the need for accurate nonlinear characterization and modeling of radio frequency (RF) transistors to enable the predictable design of high-performance circuits and systems.
ne solution offering an answer to this dilemma is Agilent Technologies’ PNA-X vector network analyzer, the world’s most integrated and fl exible microwave test engine for accurately measuring active devices like amplifi ers, mixers, and frequency converters in coaxial, fi xtured, and on-wafer environments (Figure 1). The PNA-X features an optional Nonlinear Vector Network Analyzer (NVNA) application for fast, accurate characterization and design of active devices and components.  The award-winning Agilent NVNA is the industry’s fi rst interoperable measurement and simulation environment for designing nonlinear components. Using the PNA-X’s NVNA, X-parameters* are measured and then used to create X-parameter models that can be imported into Agilent’s Advanced Design System (ADS), SystemVue, and Genesys to simulate actual linear and nonlinear component behavior. X-parameters represent a new category of nonlinear network parameters for deterministic, highfrequency design, which can be used to characterize both a components’ linear and nonlinear behavior. Thanks to the PNA-X and its NVNA application, engineers and scientists can now have the highest level of insight into nonlinear device behavior. Let’s take a closer look.