This paper describes the design of analog pseudo-differential fractional frequency filter with the order of (2 + α), where 0 < α < 1. The filter operates in a mixed-transadmittance mode (voltage input, current output) and provides a low-pass frequency response according to Butterworth approximation. General formulas to determine the required transfer function coefficients for desired value of fractional order α are also introduced. The designed filter provides the beneficial features of fully-differential solutions but with a less complex circuit topology. It is canonical, i.e. employs minimum number of passive elements, whereas all are grounded, and current conveyors as active elements. The proposed structure offers high input impedance, high output impedance, and high common-mode rejection ratio. By simple modification, voltage response can also be obtained. The performance of the proposed frequency filter is verified both by simulations and experimental measurements proving the validity of theory and the advantageous features of the filter.

No abstract

In this paper, the application of universal voltage conveyors in the design of fractional-order frequency filters is presented. Using the continued fraction expansion approach, circuit solutions approximating the low- and high-pass fractional transfer function are proposed, analyzed and their behavior verified both by simulations and experimental measurements. The considered order of the filters is [Formula: see text], where [Formula: see text]. The proposed filters operate in the voltage-mode, are of minimal configuration and are easy to be connected in cascade as their output impedance is low, zero in theory.

In the paper, a universal preudo-differential second-order filter operating in voltage mode, where both intup and output are differential, is presented. The circuit is formed by one differential difference current conveyor (DDCC), two differential voltage current conveyors (DVCCs), and five passive elements. The filter is characterized by high input impedance, minimum number of passive elements that are all grounded, and high common-mode rejection ratio (CMRR). The proposed filter structure is able to realize all five standard frequency filter responses. Non-ideal analysis has been performed by considering the real parasitic parameters of the active elements. The optimization of passive element values has been done in terms of minimal shift of the pole-frequency and to obtain the maximum stop-band attenuation of the high-pass filter response. Functionality is verified by simulations and experimental measurements using readily available integrated circuit UCC-N1B 0520.

No abstract