
Academic Year 
2023/2024 
Name 
Dott.  MI (1380) Ingegneria dell'Informazione / Information Technology 
Programme Year 
1 
ID Code 
061654 
Course Title 
SYNTHESIS AND DESIGN TECHNIQUES FOR RF FILTERS 
Course Type 
MONODISCIPLINARY COURSE 
Credits (CFU / ECTS) 
5.0 
Course Description 
Introduction. Definition of filters Specifications: Filter Mask  Design approaches for distributedparameters filters. Recall of microwave circuit fundamentals for filters design: equivalent circuit concept, resonators, resonant modes, coupled resonators, examples and discussion.
Basics of lumped filters synthesis: equivalent lowpass domain, frequency transformation, impedance conservation property. Approximation of the filtering function: analytical solutions for allpole functions (Butterworth, Chebycheff). Equations for the elements of ladder lowpass prototype. Denormalized band
pass network suitable for microwave implementations (all resonators of the same type). Redundancy of the network. General relations among the parameters. Practical implementations: allequal resonators. Example: iriscoupled waveguide filters.
Various types of allpole inline microwave filters. Solutions with assigned inverters (microstrip and coaxial implementation). Coupled lines filters. Array of coupled lines: comb and interdigital filters. Passband filters with asymmetric transmission zeros. Definition of characteristic polynomials. Assumptions for small bandwidth synthesis. Approximation problem: polezero placement, generalized Chebicheff function. Evaluation of characteristic polynomials (lossless condition). Complex zeros for phase
equalization.
Synthesis of normalized lowpass filters with transmission zeros. Crosscoupled topologies, canonical prototypes. Normalized coupling matrix and its properties. Evaluation of the coupled matrix for canonical prototypes and reconfiguration. Direct synthesis of the lowpass network by means of extraction of components. Denormalization of the lowpass network. Universal parameters of the filter: resonating
frequencies, coupling parameters, external Qs.
Reconfiguration of the coupling matrix. Cascadedblock configuration. Basic blocks and associated properties. Rules for the cascaded blocks generation. Special topologies: box sections, culdesac. Extractedpole filters. Alternative solution for introducing transmission zeros. Direct extraction of a transmission zero (imaginary root of the transmission polynomial). A new element in the equivalent circuit:
the nonresonant node. Synthesis of extractedpole lowpass equivalent networks. Denormalization problem: extension of the coupling coefficient concept to networks with nonresonating nodes.
The practical design approach to high selectivity RF filters. Choice of electrical parameters for satisfying the assigned attenuation mask. Effect of introducing transmission zeros with finite unloaded Q resonators. Introduction of design margins for compensating temperature drifts. Choice of filter topology. Effect related to the power flowing through the filter: excess voltages across the real resonators and possible produced effects. Examples of microwave filters implemented with extractedpole configuration.
Approach to the dimensioning of narrow band microwave filters. Selection of the physical resonators (cavities and modes). Approximated (initial) dimensioning based on the synthesized coupling coefficients. Improvement of the design exploiting an accurate characterization of the physical structure of the filter (electromagnetic modeling). Extraction of equivalent circuits and coupling coefficients from EM simulation of coupled cavities. Outlines of smart optimization techniques (space mapping). 
ScientificDisciplinary Sector (SSD)

SSD Code

SSD Description

CFU

INGINF/02

ELECTROMAGNETIC FIELDS

5.0


Alphabetical group

Name

Teaching Assignment Details

From (included)

To (excluded)

A

ZZZZ

Gentili Gian Guido, Macchiarella Giuseppe


