MI (1380) - INGEGNERIA DELL'INFORMAZIONE / INFORMATION TECHNOLOGY

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061654 - SYNTHESIS AND DESIGN TECHNIQUES FOR RF FILTERS

Programma dettagliato e risultati di apprendimento attesi

Course description The course is aimed to provide a solid background in the synthesis and designtechniques for electrical filters used at high frequencies (above 1 GHz), usingdistributed implementations. At the end of the course the student will be able toapproach the synthesis of a wide class of narrowband filters.

Program Introduction to RF filters. Classification and general definitions. Possible approachesto the design. Technique based on the equivalence with lumped-elements filters(narrowband approximation). Concept of coupled microwave cavities: equivalent circuit representation,characteristic parameters (resonant frequency, equivalent reactance/susceptance,coupling coefficient), relationships between insertion loss, loaded and unloaded Q. Synthesis of narrowband lumped-element filters: definition of the characteristic function. Definition of the requirements (attenuation mask). Frequency transformation: mapping of the filter response into a normalized frequency domain(low-pass). Synthesis of the filter in the transformed domain and evaluation of the de-normalized network. Circuit components (resonators and inverters). Analytical evaluation of a normalized prototype for particular all-pole characteristic functions (Butterworth, Chebycheff). Prototype de-normalization for microwave filter synthesis: in-line topology with resonators of the same type (series or shunt), coupled through inverter. Analytical relationships among the equivalent circuit parameters, general design equations. Synthesis of filters with transmission zeros: Introduction of the characteristic polynomials and their meaning. The generalized Chebycheff approximation: techniques for evaluating the characteristic polynomials determining an equiripple response in passband with assigned transmission zeros. Synthesis of the normalized prototype with non-adjacent couplings: the normalized coupling matrix. Analytical expressions for the filter response evaluation. De-normalized parameters. Canonical networks (folded, wheel, transversal). Reconfiguration of the filter topology: similarity transformations (analytical definition and specific properties). Synthesis of extracted-pole configurations. Software for the synthesis of cascaded-block filters: example of designs (from the specifications to the de-normalized parameters).

Teaching organization The course includes traditional lectures and practical design sessions. During these latter the student will by guided through real designs, using suitable CAD tools.

Note Sulla Modalità di valutazione

At the end of the course each student is requested to realize a project with assigned specs. During the exam, the student will present the result of the project, explaining the solutions adopted

Intervallo di svolgimento dell'attività didattica

Data inizio

Data termine

Calendario testuale dell'attività didattica

March 11, 2024, 9-12: Introduction to the course, recall of required background, distributed& lumped circuits, filters basic concepts. March 13, 2024, 9-12: Polynomial approximation concept. Synthesis in the normalized low-pass domain. Elementary filtering characteristics (Chebycheff, Butterworth).Implementation with distributed components (coupled resonant cavities) March 15, 2024, 9-12: Examples of design. Use of specialized software for the synthesis. March 18, 2024, 9-12: Transmission zeros in the filter response. Evaluation of theapproximation characteristic (non symetrical response). March 20, 2024, 9-12: Topologies of cross-coupled filters March 22, 2024, 9-12: Discussion and development of design examples using specializedsoftware March 25, 2024, 9-12: Extracted-pole filters March 27, 2024, 9-12: Practical dimensioning of filters structures at microwave frequencies March 29, 2024, 9-12: Concluding remarks