ThisbookwaswrittenforuseinacourseatLinkopingUniversityandtoaidthe .. electricalengineertounderstandanddesignanalogfilters.Mostoftheadvanced mathematicsrequiredforthesynthesisofanalogfiltershasbeenavoidedby providingasetofMATLABfunctionsthatallowssophisticatedfilterstobe designed.MostofthesefunctionscaneasilybeconvertedtorununderOctaveas well. Thefirstchaptergivesanoverviewoffiltertechnologies,terminology, andbasicconcepts.Approximationofcommonfrequencyselectivefilters andsomemoreadvancedapproximationsarediscussedinChapter2.The reader is recommended to compare the standard approximation with respecttothegroupdelay,e.g.,Example2.5,andlearntousethecor- sponding MATLAB functions. Geometrically symmetric frequency tra- formationsarediscussedaswellasmoregeneralsynthesisusingMATLAB functions. Chapter 3 deals with passive LC filters with lumped elements. The reader may believe that this is an outdated technology. However, it is stillbeingusedandmoreimportantlythetheorybehindalladvancedfilter structures is based on passiveLC filters. This is also the case for digital and switched-capacitor filters.
The reader is strongly recommended to carefully study the principle of maximum power transfer, sensitivity to element errors, and the implications of Equation (3.26). MATLAB fu- tionsareusedforthesynthesisofladderandlatticestructures.Chapter4 deals with passive filters with distributed elements. These are useful for veryhigh-frequencyapplications,butalsointhedesignofcorresponding wavedigitalfilters. InChapter5,basiccircuitelementsandtheirdescriptionasone-,two-,and three-portsarediscussed. Chapter 6 discusses first- and second-order sections using single and multiple amplifiers. The reader is recommended to study the implication ofthe gain-sensitivityproductandthetwo-integratorloop.Chapter7d- cusses coupled forms and signal scaling, and Chapter 8 discusses various methods for immitance simulation. Wave active filters are discussed in v vi Preface Chapter9andleapfrogfiltersinChapter10.Finally,tuningtechniquesare discussedinChapter11. Textwithasmallerfontiseithersolvedexamplesormaterialthatthereader mayskipoverwithoutlosingthemainpoints.