Generalized two-port network based fractional order filters

2019JournalKhalil N.A.Radwan A.G.Said L.A.Soliman A.M.

This paper proposes a general prototype fractional order filter based on a two-port network concept with four external impedances. Three induced classifications from the general prototype are extracted with one, two and three external impedances, achieving ten possible generalized topologies. The external impedances are fractional-order elements and resistors. There are forty-six filters divided into twenty-two and twenty-four different general fractional filters of order “?” and order “? + ?”, respectively. The general transfer functions, the necessary network conditions, and the critical frequencies are presented for each topology in terms of the transmission matrix parameters of a general two-port network and the fractional order parameters. These aspects add extra degrees of freedom, which increase the design flexibility and controllability; it is up to the designer to select any network suitable for his application. Six special cases of two-port networks based on the second generation current conveyor (CCII) active building block are synthesized to realize the proposed topologies. CCII family has four members that yield twenty-four different transmission matrices, resulting 480 filters. Due to the large number of the introduced filters, selected cases are investigated in detail to validate the theoretical findings through numerical simulations, Spice simulations, and experimental results. © 2019 Elsevier GmbH

Fractional order Chebyshev-like low-pass filters based on integer order poles

2019Abdelaty A.M.Ahmed W.A.JournalRadwan A.G.Soltan A.

Chebyshev filter is one of the most commonly used prototype filters that approximate the ideal magnitude response. In this paper, a simple and fast approach to create fractional order Chebyshev-like filter using its integer order poles is discussed. The transfer functions for the fractional filters are developed using the integer order poles from the traditional filter. This approach makes this work the first to generate fractional order transfer functions knowing their poles. The magnitude, phase, step responses, and group delay are simulated for different fractional orders showing their Chebyshev-like characteristics while achieving a fractional order slope. Circuit simulations using Advanced Design Systems of active and passive realizations of the proposed filters are also included and compared with Matlab numerical simulations proving the reliability of the design procedure. Experimental results of a two-stage active realization show good accordance with ADS and Matlab results. © 2019 Elsevier Ltd

Reconfigurable chaotic pseudo random number generator based on FPGA

2019JournalMadian A.H.Radwan A.G.Rezk A.A.Soliman A.M.

This paper presents an FPGA Pseudo Random Number Generator (PRNG) that is based on the Lorenz and Lü chaotic systems. These two systems are used to generate four different 3D chaotic attractors. One attractor is generated from Lorenz while the other three attractors are generated from Lü. The output attractor of the proposed PRNG can be reconfigured during real time operation using an efficient hardwired shifting and multiplexing scheme. Furthermore, in order to exploit the proposed reconfiguration feature, the proposed PRNG has been embedded in an FPGA cascaded encryption processor that ciphers the input data from one up to four times successively. In each ciphering operation the PRNG is set to a new configuration and is initialized according to a part of the encryption key. The size of the encryption key can be varied according to the number of required ciphering operations. The proposed PRNG has been realized using VHDL, synthesized on Xilinx using the FPGA device XC5VLX50T, and analyzed using MATLAB and the NIST statistical suite. The proposed PRNG has utilized only 1.4% from the FPGA’s slices, achieved an operating frequency up to 78 MHz, and successfully passed all the NIST statistical tests. © 2018 Elsevier GmbH

Comprehensive comparison based on meta-heuristic algorithms for approximation of the fractional-order Laplacian s ? as a weighted sum of first-order high-pass filters

2019Abdelaty A.M.Elwakil A.S.JournalPsychalinos C.Radwan A.G.Yousri D.

To implement an approximation of the fractional order Laplacian operator s ? as a weighted sum of high pass filter sections, it is essential to extract the cutoff frequencies and filter gains of each section in order to achieve the lowest error possible