Electronically adjustable realizations of power-law filters

• Κύριος συγγραφέας: Τσουβάλας, Ερρίκος
• Άλλοι συγγραφείς: Tsouvalas, Errikos
• Γλώσσα: English
• Έκδοση: 2022
• Θέματα: Non-integer order filters; Fractional-order filters; Power-law filters; Tunable filters; Φίλτρα κλασματικής τάξης; Τελεστικοί ενισχυτές διαγωγιμότητας

This MSc Thesis deals with a new category of fractional-order filters, realized without employing a fractional-order Laplacian operator. In particular, the design of a generalized structure which is capable of implementing power-law filters derived from 1st and 2nd-order mother filter functions is presented. Different approximation tools have been evaluated in this work, for choosing the most efficient for approximating the behavior of power-law filters. After presenting and comparing the results of these methods and selecting the case with the the lowest error, the derived integer-order rational transfer functions, can be implemented using conventional filter design techniques. Thus, there is no need for fractional-order elements, which are not yet commercially available, to realize this class of filters. The proposed structure is realized using Operational Transconductance Amplifiers (OTAs) as active elements, because of the electronic tuning capability of their characteristics through appropriate dc bias currents. The MOS transistors of the OTAs were selected to operate in weak inversion region in order to achieve low power consumption and low supply voltage. The performance of the proposed system is evaluated through simulation results that have been derived, using the Cadence software and the Design Kit provided by the Austria Mikro Systeme (AMS) CMOS 0.35\,\mu m technology process.