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2.19: Summary

  • Page ID
    46088
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    Radio frequency and microwave filter design combines the mathematical synthesis of a circuit with the required performance and the intuitive realization that particular structures inherently have a desired frequency selectivity. The art of filter design is to direct the mathematical synthesis and companion circuit so that the circuit structures in the synthesized filter prototype match the functionality of physical microwave structures. A very important step in this process is the development of circuit equivalent models of physical structures. Once a microwave filter with appropriate topology has been designed and the close-to-final physical filter is designed, the physical layout is optimized in a circuit simulator to account for parasitics and higher-order EM effects.

    A similar design procedure applies to active filter designs where particular circuit topologies, for example, the biquad network blocks, are identified and exploited. The synthesis approach provides design insight and exploitation all parameters of a transfer function, leading to optimum network topologies. Synthesis can be time consuming and specialized, but it is the only way to develop filters with optimum performance. Insight gained during design identifies yield issues and provides the basis for inventing new filter topologies.

    Further Reading

    The design of microwave filters has a rich tradition. Many excellent books and articles have been written about microwave filter design techniques. Books and articles with extensive treatments are references [1, 3, 4, 14, 16, 17, 18, 19, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46]. However the most important systematic approaches to microwave filter design were presented in this chapter. Many journal and conference papers present topologies in various technologies that can be used to implement filters. The best way to locate these papers is to search using the specifics of the technology of interest. For example “wideband microstrip bandstop filters on glass substrates” will yield a list of papers on the topic. There are many small companies that specialize in different types of filter design. For very high performance filters, for example in basestation applications, the number of designers and vendors is quite small and filter designers follow the literature and patents closely. For designers building microwave systems with small to medium volumes the best approach is to use microstrip design. For bandpass microstrip design the most common choice is to use filter design based on coupled microstrip design which is considered in the next chapter.


    2.19: Summary is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.

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