A NULL-convention circuit based on dual-rail current-mode differential logic is proposed for a high-performance asynchronous VLSI. Since input/output signals are mapped to dual-rail current signals, the NULL-convention circuit can be directly implemented based on the dual-rail differential logic, which results in the reduction of the device counts. As a typical example, a NULL-convention logic based full adder using the proposed circuit is implemented by a 0.18 µm CMOS technology. Its delay, power dissipation and area are reduced to 61 percent, 60 percent and 62 percent, respectively, in comparison with those of a corresponding CMOS implementation.

Fundamental limitation on assisting a write margin (WRTM) by reducing the cell terminal bias (VDDM) has been made clear for the first time and the new cell terminal biasing scheme featuring a differential VDDM (Diff-VDDM) control has been proposed to address the issues which the conventional schemes proposed so far can not overcome [1]-[5]. Since Diff-VDDM biasing scheme can meet the both of the requirements simultaneously of 1) reducing drivability for the PMOS load transistor on the "Low" written bit-line (BL) side, and 2) increasing drivability for the other side PMOS for a write recovery, it can provide a lower minimum operating voltage (Vdd_min) for the write operation even if considering a sufficiently-large random threshold voltage (Vth) variations. The following points have been shown based on an actual 65 nm CMOS device variation data and the implemented layout data that 1) Vdd_min for the write operation can be lowered from Vdd=1.1 V down to 0.8 V when considering a 4-sigma (σ) variation, 2) the write recovery time can be reduced by 92% and 70% that for the conventional schemes [1],[2] at Vdd=0.7 V and 1.0 V, respectively, and 3) WRTM defined by the percentage (%) of the required (BL pull-down level/Vdd) to flip the cell nodes for the write operation can be relaxed by 2.6-fold and 1.4-fold that for the conventional schemes [1],[2] at Vdd=0.75 V and 1.0 V, respectively. As an actual implementation in a 65 nm CMOS, a 32-kbit single-port SRAM macro design and the measured butterfly curves have been demonstrated.

In this letter, it is shown that a MAP detector can be employed with differential pulse-position modulation (L-DPPM) in an indoor optical wireless system. The MAP detector error performance is evaluated and compared with that of a hard-decision detector and MLSD over an intersymbol interference channel. It is shown that a MAP detector provides superb performance even in a dispersive channel with high DT.

A new static storage component, a quaternary flip-flop which consists of two-bit storage elements and three four-level voltage comparators, is proposed for a high-performance multiple-valued VLSI-processor datapath. A key circuit, a differential-pair circuit (DPC), is used to realize a high-speed multi-level voltage comparator. Since PMOS cross-coupled transistors are utilized as not only active loads of the DPC-based comparator but also parts of each storage element, the critical delay path of the proposed flip-flop can be shortened. Moreover, a dynamic logic style is also used to cut steady current paths through current sources in DPCs, which results in great reduction of its power dissipation. It is evaluated with HSPICE simulation in 0.18 µm CMOS that the power dissipations of the proposed quaternary flip-flop is reduced to 50 percent in comparison with that of a corresponding binary CMOS one.

We have developed a solid-electrolyte nonvolatile switch (here we refer as NanoBridge) with a low ON resistance and its small size. When we use a NanoBridge to switch elements in a programmable logic device, the chip size (or die cost) can be reduced and performance (speed and power consumption) can be enhanced. Developing this application required solving a couple of problems. First, the switching voltage of the NanoBridge (0.3 V) needed to be larger than the operating voltage of the logic circuit (>1 V). Second, the programming current (>1 mA) needed to be suppressed to avoid large power consumption. We demonstrate how the Nanobridge enhances the switching voltage and reduces the programming current.

Since the control input of a feedback linearizable system depends on the diffeomorphism, the transient behavior of the controlled system is different. In this paper, we propose a switching rule for selecting a diffeomorphism so that the transient behavior is improved and the switched system is stable. Specifically, we show the sufficient condition for the exponential stability and the exponential upper bound of the trajectory of the switched system.

In current IP-based networks, the application of window-based end-to-end flow control, including TCP, to ensure reliable flows is an essential factor. However, since such a flow control is provided by the end hosts, end-to-end control cannot be applied to decision-making in a time-scale shorter than the round-trip delay. We have previously proposed a diffusion-type flow control mechanism to realize the extremely time sensitive flow control that is required for high-speed networks. In this mechanism, each network node manages its own traffic only on the basis of the local information directly available to it, by using predetermined rules. The implementation of decision-making at each node can lead to optimal performance for the whole network. Our previous studies showed that the mechanism works well, by itself, in high-speed networks. However, to apply this mechanism to actual networks, it needs to be able to coexist with other existing protocols. In this paper, we investigate the performance of diffusion-type flow control coexisting with TCP. We show that diffusion-type flow control can coexist with TCP and the two can be complementary. Then, we show that a combination of both controls achieves higher network performance than TCP alone in high-speed networks.

A 3 dimensional (3D) error diffusion method based on edge detection for flat panel display (FPD) is presented. The new method diffuses errors to the neighbor pixels in current frame and the neighbor pixel in the next frame. And the weights of error filters are dynamically adjusted based on the results of edge detection in each pixel's processing, which makes the weights coincide with the local edge feathers of input image. The proposed method can reduce worm artifacts and improve reproduction precision of image details.

The present paper introduces a new construction of a class of binary periodic sequence set having a zero-correlation zone (hereinafter binary ZCA sequence set). The cross-correlation function and the side-lobe of the auto-correlation function of the proposed sequence set is zero for the phase shifts within the zero-correlation zone. The present paper shows that such a construction generates a binary ZCA sequence set by using a cyclic difference set and a collection of mutually orthogonal complementary sets.

The diffraction of a transverse magnetic (TM) plane wave by a perfectly conductive surface made up of a periodic array of rectangular grooves is studied by the modal expansion method. It is found theoretically that the reflection coefficient approaches -1 but no diffraction takes place when the angle of incidence reaches a low grazing limit. Such singular behavior is shown analytically to hold for any finite values of the period, groove depth and groove width and is then demonstrated by numerical examples.

Binary sequences with two-level periodic autocorrelation correspond directly to cyclic (v, k, λ)-designs. When v = 4t-1, k = 2t -1 and λ = t-1, for some positive integer t, the sequence (or design) is called a cyclic Hadamard sequence (or design). For all known examples, v is either a prime number, a product of twin primes, or one less than a power of 2. Except when v = 2k-1, all known examples are based on quadratic residues (using the Legendre symbol when v is prime, and the Jacobi symbol when v = p(p+2) where both p and p+2 are prime); or sextic residues (when v is a prime of the form 4a2 + 27). However, when v = 2k-1, many constructions are now known, including m-sequences (corresponding to Singer difference sets), quadratic and sextic residue sequences (when 2k-1 is prime), GMW sequences and their generalizations (when k is composite), certain term-by-term sums of three and of five m-sequences and more general sums of trace terms, several constructions based on hyper-ovals in finite geometries (found by Segre, by Glynn, and by Maschietti), and the result of performing the Welch-Gong transformation on some of the foregoing.

The proportional delay differentiation (PDD) model provides consistent packet delay differentiation between classes of service. Currently, the present schedulers performing the PDD model cannot achieve desired delay proportion observed in short timescales under light/moderate load. Thus, we propose a Non-Work-Conserving (NWC) scheduler, which utilizes the pseudo-waiting time for an empty queue and forces each class to compare its priority with those of all other classes. Simulation results reveal that NWC outperforms all current schedulers in achieving the PDD model. However, NWC suspends the server from transmitting packets immediately if an empty class has the maximum priority, resulting in an idle server. Therefore, we further propose two approaches, which will serve a best-effort class during this idle time. Compared with other schedulers, the proposed approaches can provide more predictable and controllable delay proportion, accompanied with satisfactory throughput and average queuing delay.

Visual criteria for diagnosing liver diseases, such as cirrhosis, from ultrasound images can be assisted by computerized texture classification. This paper proposes a system applying a PNN (Pyramid Neural Network) for classifying the hepatic parenchymal diseases in ultrasonic B-scan texture. In this study, we propose a multifractal-dimensions method to select the patterns for the training set and the validation sets. A modified box-counting algorithm is used to calculate the dimensions of the B-scan images. FDWT (Fast Discrete Wavelet Transform) is applied for feature extraction during the preprocessing. The structure of the proposed neural network is testified by training and validation sets by cross-validation method. The performance of the proposed system and a system based on the conventional multilayer network architecture is compared. The results show that, compared with the conventional 3-layer neural network, the performance of the proposed pyramid neural network is improved by efficiently utilizing the lower layer of the neural network.

To provide basic considerations for the realization of methods for predicting the electromagnetic (EM) radiation from a printed circuit board (PCB) with plural signal traces driven in the even-mode, the characteristics of the EM radiation resulting from two signal traces on a PCB are investigated experimentally and by numerical modeling. First, the frequency responses of common-mode (CM) current and far-electric field as electromagnetic interference (EMI) are discussed. As the two traces are moved closer to the PCB edge, CM current and far-electric field increase. The frequency responses in the two signal trace case can be identified using insights gained from the single trace case. Second, to understand the details of the increase in CM current, the distribution of the current density on the ground plane is calculated and discussed. Although crosstalk ensues, the rule for PCB design is to keep two high-speed traces on the interior of the PCB whenever possible, from the point of view of EM radiation. Finally, an empirical formula to quantify the relationship between the positions of two traces and CM current is provided and discussed by comparing four different models. Results calculated with the empirical formula and finite-difference time-domain (FDTD) modeling are in good agreement, which indicates the empirical formula may be useful for developing EMI design guidelines.

Switching characteristics such as wavelength dependency and phase dependency are investigated for our proposed switch which consists of waveguide-type Raman amplifiers and 3-dB couplers. As a result, the available range of wavelength and phase shift due to nonlinear effect are estimated about 20 nm around 1.55 µm and about 10 degrees, respectively.

We present room temperature current voltage characteristics from SiGe interband tunneling diodes epitaxially grown on highly resistive Si(001) substrates. In this case, a maximum peak to valley current ratio (PVCR) of 5.65 was obtained. The possible integration of a SiGe tunnel diode with a strained Si transistor lead us to investigate the growth of SiGe interband tunneling diodes on Si0.7Ge0.3 virtual substrates. A careful optimization of the layer structure leads to a maximum PVCR of 1.36 at room temperature. The latter value can be further increased to 2.26 at 3.7 K. Our results demonstrate that high quality SiGe interband tunneling diodes can be realized, which is of great interest for future memory and high speed applications.

A novel resonant tunneling diode (RTD) oscillator is proposed, which overcomes the problems of the conventional RTD oscillators, such as the low-frequency spurious oscillation and the bias instability. Our proposal consists of two RTDs connected serially, and the resonator connected to the node between two RTDs. This circuit separates the oscillation node from the bias nodes, and suppresses the above mentioned problems. This relaxes the severe restriction on the RTD area, and makes it possible to supply higher power to a load. Circuit simulation shows that with this circuit more than 2 mW power can be supplied to the 50 Ω resistive load at 100 GHz using RTDs having 105 A/cm2-peak current density and 20 µm2-area. It also shows that the dc-to-RF conversion efficiency is as good as that of conventional ones. Furthermore, we have studied the extension of this oscillator having 4 RTDs connected serially. Circuit simulations revealed that using this circuit the power can be doubled with a good conversion efficiency.

We have fabricated and investigated InGaAs Esaki tunnel diodes, grown on GaAs or InP substrates, of varied defect densities. The tunnel diodes exhibit the same I-V characteristics in spite of the variation of defect density. Under the simple thermal annealing and forward current stress tests, the change in the valley current was not observed, indicating that defects were not increased. On the other hand, the reduction in the peak current due to the carbon diffusion was observed under both tests. The diffusion was enhanced by the stress current owing to the energy dissipation associated with the nonradiative electron-hole recombination. From the reduction rates of the peak current, we obtained the thermal and current-enhanced carbon diffusion constants in InGaAs, which are independent of defect density. Although thermal diffusion of carbon in InGaAs is comparable with that in GaAs, the current-induced enhancement of diffusion in InGaAs is extremely weaker than that in GaAs. The difference between activation energy of thermal and current-enhanced diffusion is 0.8 eV, which is independent of stress current density and close to InGaAs bandgap energy. This indicates that the current-enhanced diffusion is dominated by the energy dissipation associated with nonradiative band-to-band recombination. This enhancement mechanism well explains that the current-induced enhancement is independent of defect density and extremely weak. We also have found that the current-enhanced diffusion constant is approximately proportional to the square of current density, suggesting that the recombination in the depletion layer dominates the current-enhanced diffusion.

In this paper we propose a road object extraction technique based on an active contour model (snake) considering inertia and differential features in a movie. Different energy functions can be applicable to snake in order to use information of various objects and various environments. Using many methods for tracking a moving object, snake can be applied to a scene frame by frame. Initial positions of the control points in a frame can refer to the results in the previous frame. We focus on the inertia that works between object shapes in the previous and present frames. In this research inertia is the tendency of a control point to resist its changes in its state of motion in an image space. We introduce an external energy for snake based on inertia of control points. Internal energy functions based on differential features of road geometry are also introduced to extract straight, circular and S-shaped road segments smoothly. The proposed method is applied to extract road geometry from a movie taken by a camera equipped on the flont of a vehicle. Experimental results indicate the availability of the proposed method which is to extract road geometry smoothly and to improve its robustness.

Recently, Yoon et al. exhibited the vulnerability of the smart-card-equipped password based authentication protocol proposed by Chien et al. to the Denning-Sacco attack. Furthermore, they also pointed out that the protocol does not provide the perfect forward secrecy. Accordingly, they presented an enhanced protocol to strengthen the security. This letter, however, demonstrates an interleaving attack on the Yoon et al.'s improved protocol and also discusses how to defend the protocol from the attack presented here.