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Coupled oscillatory systems are suitable to express synchronization phenomena, and it is important to unveil nonlinear phenomena. In this study, we investigate the synchronization phenomena observed in four coupled van der Pol oscillators as a regular tetrahedron form. We observe the rotation of the phase difference between anti-phase state and asynchonization state. Furthermore, the sojourn time...
In this study, synchronization phenomena observed in coupled polygonal oscillatory networks with frustration is investigated. In this oscillatory system, dilemma is created by the shared branch. We investigate the phase difference between adjacent oscillators when the number of oscillators connected to one side of the polygonal network is increased for considering the large-scale oscillatory networks.
One of the problems with on-chip active-RC filters is that in order to satisfy tight specifications accurately, they need to be fine-tuned. This becomes more difficult with increasing filter order. In this paper, we introduce a simplified tuning method which is obtained by a new structure consisting of a filter section of second- or third-order (Biquad or Bitriplet which is referred to as a ‘tuning...
This paper presents a design procedure for high-order continuous time low-pass filters based on the cascade of biquadratic cells. The proposed approach is amenable for integration, as it takes into account the maximum capacitance spread imposed by the available technology, and also allows a tradeoff between noise and maximum linear range to be met, thereby improving the dynamic range. Simulations...
Mixed-mode oscillations in a slow-fast dynamical system under weak perturbation are studied numerically. First, we make a band-limited extremely weak Gaussian noise, and apply this noise to this oscillator. Then, we observe random phenomenon from numerical study even if the noise is extremely weak. The mixed-mode oscillations are submerged by chaos due to extremely weak noise. We imagine that mixed-mode...
This paper presents a new architecture for a overcurrent detection system, dedicated to fully integrated class-D audio amplifiers, that uses half the comparators than conventional architectures. A detailed implementation for a 1-W bridge-tied load (BTL) class-D amplifier, on a 0.18 µm CMOS technology is presented, showing a reduction of 28.8% in current consumption and 23.5% in silicon area, when...
The paper presents new results of pitch estimation for speech signals obtained using a pipeline algorithm. The algorithm uses instantaneous complex frequency to perform voiced/unvoiced classification and estimate the fundamental frequency for each sample of the speech signal. Its performance is evaluated using two databases containing utterances spoken by male and female English speakers.
In this paper we present a low-power low-voltage class-AB amplifier with rail-to-rail output swing capable of operating from 0.5V to 1.0V of supply voltage, and two Sample & Hold (SHA) circuits based on this amplifier. The bias current and the bandwidth of the amplifier depend on the voltage supply, so that for low-power operation a low supply voltage can be used. The two SHAs have a nominal gain...
This paper presents analytical expressions for the sensitivity of a low power envelope detector driven by a weak RF signal in the presence of a blocking signal. The envelope detector has been proposed for low power Wake-Up radios in applications such as RFID and wireless sensor systems. The theoretical results are verified with simulations of a modern short channel MOS transistor in a commonly used...
The use of rate-compatible error correcting codes offers several advantages as compared to the use of fixed-rate codes: a smooth adaptation to the channel conditions, the possibility of incremental Hybrid ARQ schemes, as well as simplified code representations in the encoder and decoder. In this paper, the implementation of a decoder for rate-compatible quasi-cyclic LDPC codes is considered. The decoder...
As wireless communication devices have increased rapidly, much attention has been paid to the spectrum resources. Cognitive Radio (CR) technology has received increasing attention as a potential approach to utilize more effectively the radio frequency bands. CRs need to dynamically and reliably determine spectral holes which could be used for secondary transmissions. In this study, wideband multichannel...
A 2.4-GHz CMOS single ended-input differential-output front-end built with a common source low noise amplifier (CS-LNA) and a switched transconductor mixer (SW-MIX) is presented. The circuit is designed and optimized to work in a ZigBee receiver. Since this is a low power consumption standard, a single-ended LNA is preferred over a fully-differential topology because it leads to lower cost in area...
This paper presents a fast and compact charger architecture for ultracapacitors with direct connection to 230V AC mains supply. The charger delivers a DC output current which allows compensation for inductive and other non-ideal behaviour in the EDLC at medium and high frequencies. The internal converter uses self oscillating control circuits which provide a variable switching frequency over a broad...
Testing an RF device in Production is expensive and technically difficult. At Wafer Test level, the RF probing technologies hardly fulfil the industrial test requirements in terms of accuracy, reliability and cost. At Package test level testing the RF parameters requires expensive RF equipments (RF automated test equipments (ATE)) and for complex RF transceivers, which address multi-modes (RF multi-paths...
This paper applies recently developed techniques for the PieceWise-Affine (PWA) approximation of explicit Model Predictive Control (MPC) to an Adaptive Cruise Control system. The optimal MPC law is approximated by using a particular class of PWA functions defined over a domain partitioned into simplices, referred to as PieceWise-Affine Simplicial functions. This approximation technique allows a very...
Artificial neural networks have been used as an important technique in modeling and optimization for engineering design. In this work, 3-step modeling strategy based on knowledge based techniques is proposed to develop new efficient modeling instead of conventional artificial neural network (ANN) modeling. The knowledge based artificial neural networks are constructed by incorporating the existing...
This paper introduces a digital architecture to implement piecewise-affine (PWA) functions based on representation methods from the lattice theory. Given an explicit and continuous PWA function, the parameters required to implement the lattice approach can be obtained by an off-line preprocessing that can be automated. Other advantages of the proposal are that it implements a continuous PWA function...
In this paper, an ultra-compact model for nanometer MOS transistors is proposed. Starting from modified and more accurate versions of classical compact models, all the main physical effects that are predominant in nanometer technologies are included in an extremely simple way. Model effectiveness is verified through simulations in a 65-nm CMOS technology.
This paper describes how a novel distortion contribution analysis can be used efficiently for improving the linearity of a nonlinear circuit. The distortion analysis technique called Volterra-on-Harmonic-Balance calculates a distortion contributions in each tone and node for each nonlinear elements of the nonlinear devices in the circuit. As the analysis provides large amount of data, also the flow...
In this study, we focus on the problem of controlling chaos in State Controlled-Cellular Neural Network (SC-CNN) based chaotic circuit, which is a counterpart realization of unfolded Chua's circuit. For this purpose, RLC based external and internal control mechanisms are applied to SC-CNN based chaotic circuit. With these applications, SC-CNN based chaotic circuit is able to exhibit the serial behavior...
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