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Active circuit model of low-frequency behavior in perovskite solar cells

The low-frequency impedance hook in perovskite solar cells (PSC) is a feature that has been frequently associated with the behavior of passive circuits of inductors or negative capacitances. However, if the experimental impedance data do not transform according to the Kramers-Kronig (KK) relations, the system does not fulfill the conditions of linearity, stability, causality and finiteness

Circuit Theory and Applications

Wideband third-order single-transistor all-pass filter

In this letter, a third-order wideband voltage-mode all-pass filter (APF) is proposed for application as a true time delay (TTD) cell. The advantages of designing a single-stage higher order filter over cascading several lower order stages are illustrated. The proposed APF circuit is based on a single metal-oxide-semiconductor (MOS) transistor and is canonical because it requires one resistor, one

Circuit Theory and Applications

Generalized Fully Adjustable Structure for Emulating Fractional-Order Capacitors and Inductors of Orders less than Two

A novel scheme suitable for the emulation of fractional-order capacitors and inductors of any order less than 2 is presented in this work. Classically, fractional-order impedances are characterized in the frequency domain by a fractional-order Laplacian of the form s± α with an order 0 < α< 1. The ideal inductor and capacitor correspond, respectively, to setting α= ± 1. In the range 1 < α< 2

Circuit Theory and Applications

Quantification of memory in fractional-order capacitors

In this study we quantify and interpret the inherent memory in fractional-order capacitors when subjected to constant current charging/discharging waveforms. This is done via a finite difference approximation of the fractional order rate equation I(t) = Cαdαv(t)/dtα (0 le; α ≤ 1) relating current to voltage in these devices. It is found that as the fractional exponent α decreases, the weight of

Circuit Theory and Applications

Extraction of bioimpedance phase information from its magnitude using a non-uniform Kramers–Kronig transform

A novel non-uniform Kramers–Kronig Transform algorithm for bioimpedance phase extraction is proposed and tested in this work. The algorithm error is studied and compared with a previously proposed phase extraction technique, also based on the Kramers–Kronig transform. Results using simulated datasets and experimental datasets confirm the excellent performance of the algorithm. © 2020, European

Circuit Theory and Applications
Agriculture and Crops

Nonlinear charge-voltage relationship in constant phase element

The constant phase element (CPE) or fractional-order capacitor is an electrical device that has an impedance of the form Z(s)=1/Cαsα, where Cα is the CPE parameter and α is a fractional dispersion coefficient of values between 0 and 1. Here we show that in the time-domain the classical linear charge-voltage relationship of ideal capacitors, q=C·v, is not valid for CPEs. In fact the relationship is

Circuit Theory and Applications

A generic impedance modeling technique

In this work, a generic impedance modeling technique is proposed. The technique is able to identify a circuit model that is most suitable for fitting measured impedance magnitude data using a genetic algorithm solver as well as the optimum circuit model parameters. Experimentally measured and simulated data sets with different noise levels are used to validate the technique. © 2020 Elsevier GmbH

Circuit Theory and Applications

Advance Interconnect Circuit Modeling Design Using Fractional-Order Elements

Nowadays, the interconnect circuits' conduct plays a crucial role in determining the performance of the CMOS systems, especially those related to nano-scale technology. Modeling the effect of such an influential component has been widely studied from many perspectives. In this article, we propose a new general formula for RLC interconnect circuit model in CMOS technology using the fractional-order

Circuit Theory and Applications
Software and Communications

FPGA Implementation of Delayed Fractional-Order Financial Chaotic System

This paper proposes digital design and realization on Field-Programmable Gate Array (FPGA) of the Fractional-order (FO) delayed financial chaotic system. The system is solved numerically using the approximated Grünwald-Letnikov (GL) method. For the purpose of FPGA realization, the short memory principle and an approximate GL with limited window size are utilized. Lookup Tables (LUTs) are employed

Circuit Theory and Applications

FPGA implementation of a chaotic oscillator with odd/even symmetry and its application

We propose a mathematical system capable of exhibiting chaos with a chaotic attractor which is odd symmetrical in the x − y phase plane but even symmetrical in the x − z and y − z phase planes respectively. A hardware implementation of the system is done on a digital FPGA platform for verification. The system is also attractive in the sense that (i) its dynamics are single-parameter controlled and

Circuit Theory and Applications