New charge pump circuits with high current drivability in low supply voltage are proposed. It generates a large gate-overdrive voltage of charge transfer MOSFET by pulling down the gate node voltage by deliberate leakage. A proper clock circuit is also presented to effectively suppress accompanied loss effects. The characteristics of the proposed charge pumps were investigated through simulation and measurement of fabricated circuit. The measurement result shows an excellent pumping performance especially under the condition of heavy load current.
The unavoidable nonidealities with switching delay in current-mode-controlled buck converters have been reported in the literature. Investigations are carried out on the dynamical mechanism and its experimental validation on an interrupted circuit with switching delay. Switching delay is seen to influence a region of a two-valued function on a discrete map, and to induce the coexistence of a periodic orbit.
Mapping is one of the most critical issues in designing a NoC-based system. A good mapping of an application to a NoC will lead to more traffic among resources, which are physically close on the chip. In this paper, we introduce several one-dimensional chaotic maps for solving the NoC mapping problem. In addition we compare the solution qualities in accordance with different criteria mainly communication cost and convergence time. The results confirm an increase, due to chaotic sequences, in the value of some performance indexes.
Generators may supply power to infinite bus through a single circuit long ac transmission line. The system becomes unstable after the clearance of a fault if the pre fault power transfer or the fault clearance time is high. Conversion of the line for simultaneous ac-dc power flow may keep the system stable with high values of pre fault power and fault clearance time. During the transient period after the clearance of the fault, ac power flow is switched off and the dc power flow is augmented to produce a retarding torque to bring back the generator to its normal speed. Fast control of dc current regulator may be used for this purpose. The circuit breakers are then reclosed and the ac power flow is resumed at its pre fault value without any oscillation. The power swing is low and the system is optimally damped at the end of first swing.
In this paper, a new perceptually weighted Euclidean distance function is proposed for the VQ of the speech signal. It employs a logarithmic preprocessing and utilizes the listening characteristics of the ear for the definition of the perceptually weighted Euclidean distance function. Simulation results show that the proposed VQ process has less spectral distortion (SD) than its conventional Euclidean counterpart does.
Operations of ferroelectric complementary metal-oxide-semiconductor (FeCMOS) circuits, which are composed of ferroelectric-gate field effect transistors (FeFETs) instead of conventional MOS FETs, are demonstrated for the first time. The FeCMOS circuits have a practical value of saving much power consumption by switching the circuit function between logic and distributed nonvolatile memory. The function switching is possible by momentary expanding supplied voltages before cutting the power-supply. We fabricate FeCMOS inverters as representative logic elements and demonstrate the function switching from logic to nonvolatile memory. As the nonvolatile memory, accurate operations of data write, sleep with no supplied voltages and nondestructive read, are verified. The nonvolatility is confirmed by output-voltage retention measurements.
In this paper, we propose a scalable distributed memory system with a low-cost hardware message-passing interface. The proposed interface improves the communication performance between nodes to decrease the overhead synchronization with a receiver reservation technique. The simulation results indicate that the performance is increased by 20% on 4x4 communications. The synthesis result of the proposed MPI indicates that the area was only 4.49% of each computing node. As a result, the proposed system is a useful embedded MPSoCs (Multiprocessor System on a Chip) for its low-cost implementation and scalability.
This paper presents a new boost dc-dc converter with high efficiency by using a partial resonant circuit. The switching devices in the proposed converter are operated by a soft-switching technique (ZCS; zero current switching, or ZVS; zero voltage switching) of a new partial resonant circuit. The partial resonant circuit makes use of a step-up inductor and a loss-less snubber capacitor. The switching control technique is simplified for the switches to drive in constant switching frequency with PWM (pulse width modulation). The results are that the switching power loss is very low and the system efficiency is high.
This paper uses homodyne detection to reduce the impact of backreflections in wavelength division multiplexing (WDM) single-fiber loopback access networks. We present the principle of our beat noise suppression scheme and the configuration of upstream signal transmission that enhances the effectiveness of the proposed technique. We also experimentally confirm that beat noises can be eliminated within the signal bandwidth with no significant waveform distortion.
A new technique to improve the integral nonlinearity of the “linear-in-dB” variable gain amplifier (VGA) by adopting a piecewise linear transfer curve rather than a single curve is presented. The conventional single curve which is the first-order approximation of the exponential function yields bigger deviation errors as the gain control code advances. The integral nonlinearity (INL) of the proposed piecewise linear curve can be managed to be smaller because one of divisional curves moves to another before the deviation becomes prominent. A generic circuit schematic without chip size overhead is suggested with its future expansion in mind, and a design in a 0.35µm CMOS process under 3.3V supply is proposed and verified.
Although the adaptive deblocking filter of H.264/AVC efficiently reduces blocking artifacts for most images, it is limited in removing the blocking artifacts of the directional edge on the block boundaries. In order to solve this problem, we propose a directional deblocking filter based on intra prediction direction. The proposed algorithm performs directional filtering according to the direction of the intra prediction mode in order to correctly find the block edge while avoiding computational burden. Experimental results show that the proposed algorithm provides subjective improvements at the directional edge and PSNR gain of up to 0.13dB.
We performed a simple numerical investigation of a silica hollow core photonic bandgap fiber whose core area was filled with water. We propose cladding parameters for the PBF designed to obtain a photonic bandgap of broader than 200nm at a center wavelength of 500nm.
The analysis and useful gas sensing properties of capillary-attached gas sensor (CGS) have recently been investigated. The aim of the present work was to investigate the possibility of applying CGS as single selective sensor in detecting organic gases. A CGS samples were fabricated and tested by exposure to five different flammable target gases, hydrogen, methanol, ethanol, acetone and 1-butanol. Classic feature extraction and classifiers were employed to analyze the transient response of CGS. Extracted features of fabricated CGS could differentiate between the pure target gases (TG) perfectly. Results indicated this fact that CGS can be applied as a smart single sensor to diagnose TGs.
We propose a novel gain-matched VCSEL with a thermally actuated cantilever structure, which enables the lasing wavelength to be matched with a gain-peak wavelength even under wide temperature changes. The proposed structure includes an AlxOy layer in an air-gap cavity, which results in the increase of the temperature dependence of lasing wavelengths. The modeling result shows a potential of wide temperature operations of over 200K.