IEEE Transactions on Circuits and Systems I: Regular Papers

For a high-accuracy current-steering digital-to-analog converters (DACs), the delay differences between the current sources is one of the major reasons that cause bad dynamic performance. In this paper, a mathematical model describing the impact of the delay differences on the DACs SFDR property is presented. The results are verified by comparison to behavioral-level simulations and to actual meas... View full abstract»

Implementation of fully integrated CMOS RF power amplifiers is a challenge owing to the low breakdown voltage of aggressively scaled CMOS transistors and parasitic effects associated with on-chip passive components. To address this problem, a parasitic-aware design and optimization paradigm and novel power amplifier circuit design techniques are proposed. The parasitic-aware synthesis described he... View full abstract»

This paper presents the analysis and design of a new low-voltage fully balanced differential CMOS current-mode preamplifier for multi-Gbps series data communications. The minimum supply voltage of the proposed preamplifier is V/sub T/+V/sub sat/. The preamplifier employs a balanced configuration to achieve large bandwidth and to minimize the effect of bias-dependent mismatches. Two new bandwidth e... View full abstract»

An accurate CMOS current source for current-mode low-voltage differential transmitter drivers has been designed and fabricated. It is composed of binary weighted current mirrors with built-in self-calibration circuits. The proposed self-measurement and calibration circuits can calibrate upon the collective effects of different error contributors due to process, power supply, and temperature variat... View full abstract»

State space harmonic distortion modeling and estimation are introduced for G/sub m/-C filters with fully balanced, weakly nonlinear tranconductors. The proposed method provides compact closed-form answers expressed explicitly in terms of the values of the circuit elements. It can be easily implemented in MATLAB and applied to G/sub m/-C filters of any order. The filter is viewed as a composition o... View full abstract»

This paper presents a computationally efficient application-specific integrated circuit (ASIC) implementation for the decoding of space-time block codes (STBCs) . Alternative methods of evaluating the originally proposed maximum-likelihood decision metrics are explored at the algorithm and architectural level. At the algorithm level, unique decoding techniques are developed that result in computat... View full abstract»

This paper describes a scalable architecture for real-time speech recognizers based on word hidden Markov models (HMMs) that provide high recognition accuracy for word recognition tasks. However, the size of their recognition vocabulary is small because its extremely high computational costs cause long processing times. To achieve high-speed operations, we developed a VLSI system that has a scalab... View full abstract»

This paper treats the problem of identification of a linear electric circuit described by an ill-conditioned mathematical model. The identification problem is considered as the problem of model parameters determination by means of processing experimental data measured for the objective circuit. Topological singularities (low-admittance cutsets and low-impedance loops) in a circuit are found to be ... View full abstract»

We show that the degree distributions of graphs do not suffice to characterize the synchronization of systems evolving on them. We prove that, for any given degree sequence satisfying certain conditions, there exists a connected graph having that degree sequence for which the first nontrivial eigenvalue of the graph Laplacian is arbitrarily close to zero. Consequently, complex dynamical systems de... View full abstract»

A new transfer function from control voltage to duty cycle, the closed-current loop, which captures the natural sampling effect is used to design a controller for the voltage-loop of a pulsewidth modulated (PWM) dc-dc converter operating in continuous-conduction mode (CCM) with peak current-mode control (PCM). This paper derives the voltage loop gain and the closed-loop transfer function from refe... View full abstract»

In the paper by Sandberg in 2003, he proved that, even if a continuous, linear, time-invariant, continuous-time system admits an impulse response, such a response does not always give a complete description of the system. In this paper, a theorem by Schwartz is used to define an impulse response under almost general assumptions, and to understand what we really know about two systems with the same... View full abstract»

In this paper, we propose an algorithm for real-time signal processing of convolutive blind source separation (CBSS), which is a promising technique for acoustic source separation in a realistic environment, e.g., room/office or vehicle. First, we apply an overlap-and-save (sliding windows with overlapping) strategy that is most suitable for real-time CBSS processing; this approach can also aid in... View full abstract»

This paper is concerned with global robust stability of a general class of discrete-time interval neural networks which contain time-invariant uncertain parameters with their values being unknown but bounded in given compact sets. We first introduce the concept of diagonally constrained interval neural networks and present a necessary and sufficient condition for global robust stability of the int... View full abstract»

A single-stage high-power-factor electronic ballast with a Class-E rectifier as a power-factor corrector is proposed. A Class-E rectifier is inserted between the front-end bridge rectifier and the bulk filter capacitor to increase the conduction angle of the bridge-rectifier diode current for obtaining low line-current harmonics. The Class-E rectifier is driven by a high-frequency sinusoidal curre... View full abstract»

A systematic methodology for circuit design is proposed for experimental verification of multidirectional multiscroll chaotic attractors, including one-directional (1-D) n-scroll, 2-D n/spl times/m-grid scroll, and 3-D n/spl times/m/spl times/l-grid scroll chaotic attractors. Two typical cases are investigated in detail: the hysteresis and saturated multiscroll chaotic attractors. A simple blockin... View full abstract»

Global robust convergence properties of continuous-time neural networks with discrete delays are studied. By employing suitable Lyapunov functionals, we derive a set of delay-independent sufficient conditions for the existence, uniqueness, and global robust asymptotic stability of the equilibrium point. The conditions can be easily verified as they can be expressed in terms of the network paramete... View full abstract»

We examine the effects of transmission-line nonidealities like series loss, terminal impedance mismatch, circuit noise, and transconductor input and output capacitances on the performance of traveling-wave (TWA) and transversal finite-impulse response (FIR) filters. A general framework is presented for the analysis and simulation of such filters in the context of a real communication channel. Simu... View full abstract»

In this paper, a digital fractional-order differentiator (FOD) is designed by using fractional sample delay. To improve the design accuracy of conventional fractional differencing and Tustin design methods at high frequency regions, the integer delay is replaced by fractional sample delay. By using the well-documented finite-impulse-response Lagrange, infinite impulse response allpass, and Farrow ... View full abstract»

This paper describes the fast-scale bifurcation phenomena of a single-stage power-factor-correction (PFC) power supply which is a cost effective design for low-power applications. The circuit employs a cascade configuration of a boost converter and a forward converter, which share an active switch and operate in discontinuous conduction mode, to provide input PFC and tight output regulation. Main ... View full abstract»

A recently reported result (S.Arik, see ibid. vol. 50, no. 1, p. 156-160, Jan. 2003) concerning the global robust stability of the equilibrium point of Hopfield-type delayed neural networks is revisited. It is shown that the result is not always right. View full abstract»