Multifunctional Electronically Reconfigurable and Tunable Fractional-Order Filter

Abstract

In this paper the authors present a multifunctional reconfigurable fractional-order filter performing a low-pass, high-pass, band-pass and band-reject transfer function. The filter is based on two types of active elements, OTA (Operational Transconductance Amplifier) and ACA (Adjustable Current Amplifier). It provides pole frequency control, depending on the values of the transconductance of the OTA elements. The quality factor is also electronically controlled, depending on the amplification of the ACA element. The order of the filter can be changed by switching the fractional-order capacitor having various values of the order. The circuit was implemented as a PCB (Printed Circuit Board) and measured in laboratory conditions. Measurement results are compared with the simulation results. The behavioural models were used for the purpose of the simulation.

Re-configurable band-stop and all-pass filter using fractional-order topology

“…These filters have an essential feature that consists of a single-input single-output topology which depends upon a certain function of the input variables [27]. Several topologies in conventional circuit theory for re-configurable filters have been documented in [28,29], however due to the simplicity of their construction, higher radio-frequency (RF) bands (GHz range) are given specific attention (i.e., electromagnetically coupled elements) [30]. The switch-less change of transfer response in these RF bands is easily solvable, even with passive solutions [31,32].…”

Electronically Reconfigurable and Tunable Fractional-Order Filter Using Resonator Concept and Feedforward Path for Low-Frequency Tone Signalization

“…On the other hand, the utilization of FO elements makes the solution stable. The main results of the analysis of solutions indicated by Table II show the following: a) there is no relation between reconfiguration of transfer responses and variation of parameters of FO device when a passive FO device is used [6], [15], [16]; b) electronic tuning (center, pole frequency) does not require modification of the set of parameters when a passive FO device is used [6], [15]; c) the passive FO device must be completely replaced when the change of order is required [6], [15], [16]; d) electronic tuning requires modification of the set of parameters when active solution of FO filter (the FO character is approximated by higher-order filter response [13]) is used [13], [14]; e) active solution of FO character offers electronic setting of the order [12]- [14], [17] but topology is very complex (many active elements [13], [14]) requiring many degrees of freedom of many parameters [13], [14]; f) electronic adjustment of stop-band attenuation (in order to set useful as well as undesirable spectral components properly) of the BP response is not solved in the reported cases; g) previous solutions do not use resonator concept; h) in some works [12], [14], [17], the number of transfer responses is quite low; i) the input impedances are not high and output impedances are not low simultaneously in several promising structures (for immediate application in voltage mode) [6], [13]- [15]. However, it cannot be considered as a direct disadvantage in current-mode solutions [5].…”

CCII Kullanılarak Akım Modlu, Kesirli Dereceli Evrensel Süzgeç Tasarımı ve Gerçekleştirilmesi

“…Kesirli dereceyi sağlamak amacıyla farklı yaklaşımlarla kapasite modelleri oluşturulmuştur [14,15]. Bu modeller kesirli türevi sağlayacak tasarımlarla elde edilmiştir.…”