دانلود کتاب طراحی و سنتز شبکه غیرفعال RF برای ارتباطات سیار – جلد 1

Without RF engineering, life as we know it today would be impossible. Most people are familiar with radar that allows them to fly safely across continents in less time than it took their ancestors to travel to the next town. They take cellphones for granted that allow them to talk to and see loved ones on the other side of the globe in real time. They rely heavily on microwave ovens to quickly cook or heat up their food after a long day’s work. When they go to the dentist, or if they break a bone, or have some other internal medical issue, they assume that their care provider will have some non-invasive way to peer inside their body to diagnose what is going on. They are not surprised when doors at their local supermarket open automatically for them as they approach, nor that stores have inventory control tags on merchandise to prevent theft. Many pet owners also pay to have microchips embedded in their loved ones to help ensure their safe return should they go astray. Anyone who has flown is only too familiar with security screening devices they must walk through before boarding the flight to help protect their safety. All of these applications rely on RF technology. As we move into the future, with the rapid growth of the Internet of Things (IoT) and self-driving cars, our dependence on such technology will become ever greater. The field of RF engineering encompasses an enormously wide domain of design and analysis. Included within it are both passive and active devices, which are frequently required to operate in unison. The devices may have operational frequencies ranging from a few hertz to those in the terahertz range, increasingly the focus of recent efforts seeking ever higher data rates, or even higher into the optical range. However, despite the seemingly wide divergence of RF technologies and applications, they all operate under the same physical laws and thus many of the same design and analytic analysis approaches are widely shared across the field. Beginning as a microwave engineer, during my career I worked as a surfaceacoustic- wave (SAW) designer, a non-destructive-testing (NDT) engineer in the oil industry, an RF front-end module designer, a power-amplifier designer, and a filter designer in the cellphone industry. Over the years, I had to develop many analytical tools to aid my design challenges. Invariably, to be sure that I fully understood the problem, I began from first principles to develop the underlying equations for a circuit that would best achieve the requirements for the device. This book is an attempt to share those fundamental design analyses, and the synthesis approaches derived from them, with the practicing RF engineer. In the early years of RF engineering, an engineer had little alternative to developing the basic circuit equations by themselves to predict the performance of a design, to best ensure it would meet the design goals. Computers were limited in their capabilities and RF design tools were rudimentary. Nowadays, in contrast, there are several excellent, very powerful, though expensive, design tools available to aid the practicing RF engineer. Two such examples are Advanced Design System® from Keysight and Microwave Office® from AWR Corporation. These allow even a relatively inexperienced RF engineer to design a circuit with a high degree of confidence that if realized, the circuit will perform much as predicted. The design tools also include very capable optimizers for improving the performance of a selected circuit configuration. However, invariably, such optimizations are very time consuming. Without a doubt, modern RF software tools are absolutely required for the design of today’s complex and compact RF devices. In particular, they are essential for incorporating the effects of parasitic and 3D interaction effects into the final design. However, a complete dependence on advanced software tools, especially in the early conceptual stages of RF circuit design, can result in designs that are nonoptimal in performance, larger, more expensive, have lower production yield, and higher cost than one conceived from a more first-principles approach. Under the constraint of time-pressure, RF engineers approaching a new design all too frequently seek to “leverage” an existing circuit design to meet the new requirements. With the advanced software design tools, this may consist of simply adding a few components to an existing design and letting the software reoptimize the circuit. This approach frees the engineer from having to spend time on any basic circuit analysis or having to consider any new fundamentally different circuit topologies that might be advantageous. Unfortunately, this design approach does not guarantee that the resulting solution is optimal for the requirements. To achieve a more optimal solution would require alternate circuit topologies be built and their performance evaluated in the software tool. Time constraints typically preclude this course of action. A principal objective of this book is to detail how analytic design approaches can be used for rapid design optimization and design of RF circuits. Formulae, algorithms, and analysis and data display techniques are presented for use by the practicing RF design engineer. Not only do these techniques allow for a rapid comparison to be made of the performance of alternate RF circuit topologies, but they also impart to the designer a deeper understanding of the critical design trade-offs that can be made for each of the solutions. The optimum circuit topology selected can then either be implemented directly, or if further refinements are needed due to, for example, parasitic interactions, used as a starting point for a more complex RF design tool for final optimization. The use of analytic solutions for RF circuit design has fallen out of favor in recent times as design engineers have increasingly shied away from writing equations and performing detailed circuit analysis. Instead, designers have become increasingly dependent on software packages to do the circuit design and optimization for them. This book is an attempt to change that by providing techniques that are relatively simple to apply and can help the designer become more creative by exploring circuit innovations that might otherwise have been time-prohibitive to consider.