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In order to avoid non-convergence and other numerical problems associated with the simulation of extremely large memristive networks, suitable models of the individual memristors need to be developed. A circuit containing thousands of memristors for finding the shortest path in a complicated maze is a typical example of a numerically challenging simulation. A benchmark circuit for testing the applications...
It is well known that thermally dependent resistive two-terminal devices formally conform to the definition of memristive systems. They can be studied as generic memristors on the assumption that their temperature is regarded as a state variable. It is shown in the paper that, due to the Joule dissipation, the parasitic memristance accompanies an arbitrary resistive two-terminal device, which is manifested...
The pinched hysteresis loop area increasing with the square of the frequency of driving harmonic signal on the assumption of constant charge delivered within the half-period belongs to the less known fingerprints of ideal memristor. The paper proves that this fingerprint holds not only for the harmonic excitation: the v-i characteristic of a memristor driven by n-times accelerated and simultaneously...
This work presents techniques for an accurate numerical simulation of memristor models. In physics-based models of extended memristors under indirect excitation, the solution of the state equations is constrained to lie on specific manifolds at all times. A possible algorithm for the determination of numerical solutions to the algebraic differential equation set typical of these systems consists of...
The paper deals with a time-domain (transient) model of a microturbine power unit for the design, optimization, and verification of control equipment. The model includes the starter motor, generator, gearbox, and single-shaft gas microturbine. In addition to the normal operational performance the model allows simulating various faults including failed ignition in the combustion chamber. Explicit formulation...
The paper deals with the analysis of accuracy of averaged models of DC-DC converters in the frequency domain. The averaged models of Boost, Buck and Buck-Boost converters are compared with results obtained using the harmonic balance method. It will be shown that the error of averaged models depends on the structure of state matrices and may reach a substantial magnitude even below the Nyquist frequency.
Whereas the memristor can be emulated via digital potentiometer controlled by a microcontroller, a similar implementation of memcapacitor and meminductor is problematic. The paper describes a synthesis of mutators which transform the emulated memristor into memcapacitor and meminductor. The transformations preserve the unambiguous constitutive relations of these elements, which are derived from the...
The paper deals with a fast numerical method for generating the Jacobian matrix of network function for large analog linear circuits. It is based on the use of cofactor matrices. The computational cost of the Jacobian is comparable to the cost of computing a single network function on selected frequencies. In addition, the method allows performing the reduction of Jacobian matrix based on large-change...
Novel differential-output quadrature oscillator employing two FB-VDBAs (Fully Balanced - Voltage Differencing Buffered Amplifiers) which are proposed for applications with fully differential architecture is described. This circuit can be also utilized as multi-phase oscillator with four independent single-ended outputs. Detailed analysis of real effects is included and its comparison with the results...
On the basis of the modified nodal analysis, universal matrices-stamps are defined for modeling several types of current conveyor. From these stamps, the so-called Dragonfly Mason-Coates' graphs are derived for a fast hand-and-paper symbolic analysis of current-conveyor circuits.
The paper deals with the implementation of multi-domain symbolic analysis in a new program, SAMD (Symbolic Analysis of Mechatronic Drives), developed with the emphasis on linearized hybrid systems combining classical electrical circuits, controllers, electro-mechanical converters and mechanical parts of electric drives. The systems analyzed can be composed of both basic elements and more complex blocks...
The paper deals with a method for accurate semisymbolic time-domain analysis of highly idealized linear lumped circuits. Pulse and step responses can be computed by means of the partial fraction decomposition. The procedure relies on an accurate computation of poles of the transfer function. The well known problem of the QR and QZ algorithms is their poor accuracy in the case of multiple roots. Moreover,...
Line-to-output and Control-to-output frequency responses describe behavior of DC-DC converters under small-signal perturbation of the input voltage or the duty ratio. The responses are routinely obtained using the state space averaging method, which represents a certain simplification. The paper deals with validity of the obtained responses. Using the harmonic balance method as the reference it will...
Nowadays, the majority of circuit simulation programs contain advanced methods for suppressing divergence of algorithms for solving algebraic-differential equations. However, some classes of circuits still cause problems - the circuits with strong feedback, flip-flop circuits, the ones characterized by macro models with unusual elements, and large distributed oscillators. In the paper, a novel method...
The paper deals with the design and optimization of blind oversampling clock and data recovery (CDR) based on FPGA prototyping. The main advantage of the oversampling CDR is the fully digital architecture, which enables the FPGA-based testing and its subsequent integration into any ASIC technology. The oversampling CDR is a promising block for free space optical (FSO) applications because of its extremely...
A universal current-mode 2nd-order filter employing two ZC-CITA (Z-copy current inverter transconductance amplifier) active elements and two grounded capacitors is proposed. The filter has one low-impedance current input and several high-impedance current outputs which are easy to combine to yield all basic types of transfer functions. The active element is implemented on the basis of commercial integrated...
An active circuit element, namely fully balanced voltage differencing buffered amplifier (FB-VDBA), is introduced. Its input stage is composed of a fully-differential operational transconductance amplifier (OTA). Voltage buffer is connected to each OTA output. Several applications are proposed which demonstrate the element's versatility. The results of SPICE simulation and measurements on experimental...
The paper deals with an adaptive high-voltage source for avalanche photodiodes. Usually, the photodiode operating point is set in open loop by a temperature dependent voltage source that compensates for the change of photodiode parameters. The proposed method is based on continuous monitoring of the diode gain by means of an optical pilot signal. Analysis of design constraints for Free-Space Optical...
The paper deals with a bridge for atmospheric Free-Space Optical links. The atmospheric turbulence causes fades whose duration is typically in the order of tens of milliseconds, which results in the loss of hundreds or thousands of packets. The loss is misinterpreted by the TCP protocol as network congestion and leads to throttling the sender transmission data rate to a fraction of real channel capacity...
The technique of averaged modeling represents a DC-DC switched converter by a continuous-time model for quantities averaged over the switching period. The paper presents a universal procedure for symbolic analysis of converters using the generalized model of PWM switch. Both line-to-output and control-to-output small-signal responses can be obtained in symbolic form. Example analyses using the symbolic...
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