IEEE Transactions on Circuits and Systems I: Fundamental Theory and Applications

A single-electron random-access memory array is designed and its operation is analyzed using Monte Carlo simulation. This memory array utilizes a basic single-electron memory cell that has been recently fabricated. Bits of information are represented by the presence or absence of a single or a small number of electrons at conducting islands. Simulation shows that selective read and write operations can be performed in this memory array.

In a state-space model of a class of linear discrete-time shift-invariant multivariable multidimensional dynamical systems, the problem of internal stability of a system is studied from various aspects. A sequence of equivalent statements is presented to characterize the necessary and sufficient conditions for the internal stability of a multidimensional dynamics. These statements are generalized to further enhance ones for meeting the stability of a mixed multidimensional-and-multicircular dynamic, while they degenerate into the stability condition of a circulant matrix when the underlining structure entirely degenerates. As a related topic, a model degree reduction problem is studied by the balancing realization method in a class of linear shift-invariant multivariable multidimensional systems.

This paper presents a sufficient condition for the uniqueness and global asymptotic stability of the equilibrium point for delayed cellular neural networks. This result improves and generalizes some of the previous stability results derived in the literature.

The analysis of synchronous commutations in switching converters is discussed in this paper. The Compensation Theorem (CT) is applied in order to define two matrices, called respectively zero-order and first-order master-slave connection matrix (Z-MSCM, F-MSCM), which allow a unified analysis of both hard and soft synchronous commutations in switching converters. The Z-MSCM and F-MSCM provide the analytical basis for studying the interactions among switching devices in any type of switching converter. The method is presented in its general formulation, valid for the analysis of switching converters including feedback circuitry and soft-switching cells. The examples presented show that the CT-based analysis of commutations is a useful and efficient tool for the comprehension of the mechanisms of synchronous commutations in switching converters and for numerical simulations.

In this work, the effect of sampling clock jitter on the SNR of an analog-to-digital (AD) conversion is investigated from a practical perspective. Aperture jitter analyses have been dealing up to now with white spectrum jitter. This assumption does not hold for the output of phase-locked loops (PLL)-like frequency synthesizers, where the spectrum is shaped by the loop transfer function. Based on a linear approximation, a powerful expression for the SNR is derived, applicable to a jitter process with a generic autocorrelation function and generic input signal. A lot of different definitions of jitter are available in the literature; this work addresses also the problem of identifying correctly among them the "effective" jitter for a given SNR. This can be profitably used in the specification as well as verification of the jitter requirements of a frequency synthesizer used as sampling clock generator in the AD converter systems. The results have been checked through numerical simulation.

This paper presents a new multi-objective evolutionary programming (MOEP)-based digital redesign scheme to find an optimal low-gain digital tracking controller for hybrid control of multi-input, multi-output (MIMO) cascaded analog systems with input time delays, having the constraints on the states and inputs. The proposed global optimization searching technique enables one to find a high-gain optimal analog controller for analog control of MIMO analog systems with specified performances and constrained states. Then, a new MOEP-based digital redesign method, taking into account the inter-sample behavior of the digitally controlled state, is developed to determine the longest possible sampling period under the state and input constraints and to reconstruct the low-gain pulse amplitude modulated (PAM) digital controller for hybrid control of the cascaded input-delay systems. The resulting controlled hybrid system is able to satisfy the state and actuator constraints without significantly affecting the overall performance of the hybrid cascaded systems with input time delays.

Variance analysis is used for the estimation of how random device parameter variation effects the behavior of analog integrated circuits. This method is very effective if the random parameter deviations can be assumed to be normally distributed and statistically independent and if the nonlinear dependence of the circuit characteristics can be linearized around the nominal (mean) parameter values. It is shown under which conditions the nonlinear dependencies of the system characteristics on the parameters have to be taken into account and how this can improve the accuracy of statistical analysis. This is illustrated with two examples: a transconductance amplifier and an analog filter.

Many practical systems in physics, chemistry, biology, engineering, and information science have impulsive dynamical behaviors due to abrupt changes at certain instants during the dynamical processes. These complex dynamical behaviors can be modeled by impulsive differential systems. This paper studies the controllability and observability issues for a general time-varying impulsive control systems. Sufficient and necessary conditions for state controllability and state observability of the impulsive control systems are established and their applications to time-invariant impulsive control systems are also discussed. Furthermore, several new results associated with variation of parameters for time-varying impulsive control systems are derived.

In this paper, we propose an effective multiway hypergraph partitioning algorithm. We introduce the concept of net-gain and embed it in the selection of cell moves. Unlike traditional FM-based iterative improvement algorithms in which the selection of the next cell to move is only based on its cell gain, our algorithm selects a cell based on both its cell-gain and the sum of all net-gains for those nets incident to the cell. To escape from local optima and to search broader solution space, we propose a new perturbation mechanism. These two strategies significantly enhance the solution quality produced by our algorithm. Based on our experimental justification, we smoothly decrease the number of iterations from pass to pass to reduce the computational effort so that our algorithm can partition large benchmark circuits with reasonable run time. Compared with the recent multiway partitioning algorithms proposed by Dasdan and Aykanat, our algorithm significantly outperforms theirs in term of solution quality (cutsize) and run time, the average improvements in terms of average cutsize over their PLM3 and PFM3 are 47.64% and 36.76% with only 37.17% and 9.66% of their run time, respectively.

In this paper, adiabatic and conventional CMOS NAND/NOR gates are analytically compared at the gate level versus the fan-in. The comparison was carried out assuming both an assigned power supply and setting it to minimize power consumption. The analysis led to simple expressions, independent of the technology used which allow us to understand how the power advantage of adiabatic logic diminishes when the complexity of the implemented Boolean function is increased. The analytical results were validated by Spice simulations using both 0.8- and 0.35-/spl mu/m CMOS technology. The analysis shows that with the technologies considered for the nonoptimized design, the adiabatic style is advantageous at frequencies lower than about 30 MHz. This advantage is drastically reduced to frequencies below 1 MHz when there is a fan-in higher than five. These values are further reduced by a factor of eight in the case of optimized design. In this paper, technological trends together with a partially adiabatic style are also considered and discussed.