Читать книгу Handbook of Microwave Component Measurements - Joel P. Dunsmore - Страница 11

The electronics industry has undergone revolutionary changes in the past 20 years. System performance has significantly advanced, physical size of hardware has shrunk, quality and reliability have greatly improved and manufacturing costs have dramatically decreased. Underlying these advances has been the phenomenal growth in RF test and measurement capability. Modern‐day RF test equipment has progressed to the point where it is not uncommon to measure signals below −100 dBm at milliseconds speed. Even more astounding is the ability to marry RF test capability with analysis software whereby test equipment can produce linear and non‐linear models of the device under test to significantly improve the life of the design engineer, using this capability.

RF and microwave components have played an important role in this revolutionary change. Component size has shrunk, parasitics have been reduced, quality standards have greatly improved and costs have reduced ten‐fold. At the same time, test fixtures and interconnects have improved to enable a higher level of precision during characterization and production measurement. In parallel with these advances, test equipment has improved to an extent where there has been a revolution in the capabilities to make precise and fast measurements of RF and microwave components. The success of a manufacturer of RF and microwave components is directly linked to the quality and capability of measuring component performance during the design, qualification and production phase of the product life cycle. From a practical point of view, the testing must be fast (1–2 seconds), the accuracy very precise (hundredths of a dB), with a high degree of repeatability. Each phase of the life cycle imposes its unique requirements for measurement accuracy and data collection.

During the design phase, full characterization of performance, including amplitude and phase, is a must in order to establish a reference for future production runs. So it becomes a necessary requirement to characterize and de‐embed the test setup and test fixtures to isolate actual device performance. Fortunately, the modern vector network analyzer provides support in this regard. Consequently, the performance data obtained during the design phase becomes the gold standard for evaluating statistical variation obtained from future production lots; and these lots are accepted or rejected based on the statistical results, with sigma generally being the statistic most closely watched by the test or QA engineer to evaluate production lot acceptance.

When published specs are provided for a component, it is very important to understand that these specifications are simply markers which allow for a first impression or summary review of the component performance. However, only when performance data and performance graphs are provided for all parameters, including both amplitude and phase, would the “real” performance of the component be known. Furthermore, in characterizing components for use in customer evaluations, it is important to provide this data both within and outside the specified bandwidth. In non‐linear components such as a frequency mixer, higher‐order harmonics of the RF and LO signals are generated, and depending on the load impedance outside the specified frequency range, these higher‐order harmonics can get reflected back into the mixer, causing an interaction between the desired signals and the unwanted harmonics. Fortunately, modern‐day analyzers can make these harmonic measurements relatively quickly and easy.

Dr. Dunsmore has captured the essence of modern‐day measurements. He provides a practical understanding of measurement capabilities and limitations. He provides a means for the test engineer to not only make measurements, but also to understand test concepts, anticipate measurement results and learn how to isolate and characterize the performance of the DUT, independent of potential errors inherent in the test environment. I am confident that this book will serve as a reference for understanding measurement methods, test block diagrams and measurement limitations so that correlation between the manufacturer and user would take place by using a common reference. This book has the potential to be an invaluable source to further the progress of the RF and microwave world.

Harvey Kaylie

President and Founder of Mini‐Circuits