Reconfigurable Fractional-Order Filter with Electronically Controllable Slope of Attenuation, Pole Frequency and Type of Approximation

journal article in Web of Science

English

This paper presents design of electronically reconfigurable fractional-order filter that is able to be configured to operate as fractional-order low-pass filter (FLPF) or fractional-order high-pass filter (FHPF). Its slope of attenuation between pass band and stop band, i.e. order of the filter, is electronically adjustable in range between 1 and 2. Also pole frequency can be electronically controlled independently with respect to other tuned parameters. Moreover, particular type of approximation can be also controlled electronically. This feature set is available both for FLPF and FHPF type of response. Presented structure of the filter is based on well-known follow-the-leader feedback (FLF) topology adjusted in our case for utilization with just simple active elements operational transconductance amplifiers (OTAs) and adjustable current amplifiers (ACAs), both providing possibility to control its key parameter electronically. Paper explains how reconfigurable 3rd-order FLF topology is used in order to approximate both FLPF and FHPF in concerned frequency band of interest. Design is supported by PSpice simulations for three particular values of order of the filter (1.25, 1.5, 1.75), for several values of pole frequency and for two particular types of approximation forming the shape of both the magnitude and phase response. Moreover, theoretical presumptions are successfully confirmed by laboratory measurements with prepared prototype based on behavioral modeling.

adjustable current amplifier; approximation; ACA; fractional-order filter; fractional-order high-pass filter; fractional-order low-pass filter; FLF; follow-the-leader feedback; fractional order; operational transconductance amplifier; OTA; reconfigurable filter.

JEŘÁBEK, J.; ŠOTNER, R.; DVOŘÁK, J.; POLÁK, J.; KUBÁNEK, D.; HERENCSÁR, N.; KOTON, J.

9. 3. 2017

World Scientific Publishing

1793-6454

JOURNAL OF CIRCUITS SYSTEMS AND COMPUTERS

26

10

Republic of Singapore

1750157-1

1750157-21

21

http://www.worldscientific.com/doi/abs/10.1142/S0218126617501572

http://hdl.handle.net/11012/70926