Implementation of fractional-order transfer functions using only capacitors

• Main Author: Πατρινός, Δημήτριος
• Other Authors: Patrinos, Dimitrios
• Language: English
• Published: 2023
• Subjects: Fractional calculus; Fractional-order circuits; Resistorless filters; CMOS analog integrated circuits; Κλασματικός λογισμός; Κυκλώματα κλασματικής τάξης; Φίλτρα χωρίς αντιστάσεις; CMOS ολοκληρωμένα κυκλώματα

Resistorless fractional-order filters can be implemented using active elements with behavior described by the transconductance parameter (gm), but this solution has the obstacle that is valid only under small-signal operation conditions. The aim of this M.Sc. Thesis is to demonstrate a novel concept for the implementation of resistorless fractional-order basic filters. This can be achieved because the impedance of a fractional-order capacitor is determined by both a “resistive” and a “capacitive” part. First of all a theoretical approach of fractional-order basic filter transfer functions is presented. In addition design examples of resistorless fractional-order filters, which are implemented with different active elements, is performed in this work. Some of these filter topologies have been experimentally tested using a CFOA as active element and a real fractional-order capacitor. Furthermore a CFOA circuit is introduced not only as schematic design but also as layout design, which have been used in order to simulate the aforementioned filter structures. The performance of the proposed filter topologies is verified through simulation results that have been extracted using Cadence and the Design kit provided by the Austria Mikro Systeme (AMS) 0.35μm CMOS technology process.