Profit Aware Circuit Design Under Process Variations Considering Speed Binning

In this paper, a profit-aware design metric is proposed to consider the overall merit of a design in terms of power and performance. A statistical design methodology is then developed to improve the economic merit of a design considering frequency binning and product price profile. A low-complexity sensitivity-based gate sizing algorithm is developed to improve economic gain of a design over its initial yield-optimized design. Finally, we present an integrated design methodology for simultaneous sizing and bin boundary determination to enhance profit under an area constraint. Experiments on a set of ISCAS'85 benchmarks show in average 19% improvement in profit for simultaneous sizing and bin boundary determination, considering both leakage power dissipation and delay bounds compared to a design initially optimized for 90% yield at iso-area in 70-nm bulk CMOS technology.     

An Integrated CAD Methodology for Evaluating MOSFET and Parasitic Extraction Models and Variability

An integrated computer-aided design (CAD) framework for evaluating MOSFET and layout parasitic extraction (LPE) models and circuit simulators used in the timing and power analysis of CMOS products is presented. This unified CAD methodology builds a step-wise understanding of the underlying parameter values in the models and their impact on circuit performance. A number of circuit experiments are included to extract the contributions of key MOSFET parameters and physical layout sensitive parasitic elements from circuit simulation results. This CAD setup thus allows easy and detailed comparison of different technologies, device models, and LPE tools to prevent possible bugs in the software as well as inaccuracies in device and parasitic models and timing tools. The software code to carry out the circuit simulations, analysis, and display of the results in an automated fashion has been specifically developed to support this framework. Some of the experiments designed for this work are also placed on the product chip for model-to-hardware correlation. The comparison of the hardware data to the model predictions points to the sources of any discrepancies and aids in tuning the product design to reflect changes in the technology as part of an overall design for manufacturing (DFM) platform     

Nonlinear Eulerian Analysis of Harmonic Generation in Traveling-Wave Tubes

A third-order nonlinear Eulerian hydrodynamic formulation was developed for the analysis of harmonic generation in helix traveling-wave tubes. The analysis was simple and computationally fast compared to Lagrangian analysis, and contrary to the existing belief, the theory could as well demonstrate the saturation behavior of the device. The performance of the theory was also found to be in close agreement with that of the Lagrangian analysis. The theory is expected to be useful as a first-hand design and simulation tool for microwave and millimetric wave traveling-wave tubes.     

A simple equivalent circuit analysis of rectangular folded-waveguide slow-wave structure

A simple yet accurate equivalent circuit model was developed for the analysis of slow-wave properties (dispersion and interaction impedance characteristics) of a rectangular folded-waveguide slow-wave structure. Present formulation includes the effects of the presence of beam-hole in the circuit, which were ignored in existing approaches. The analysis was benchmarked against measurement as well as with 3D electromagnetic modeling using MAFIA for two typical slow-wave structures operating in Ka- and Q-bands, and close agreements were observed. The analysis was extended for demonstrating the effect of the variation of beam-hole radius on the RF interaction efficiency of the device.     

Piezoelectric Nylon‐11 Nanowire Arrays Grown by Template Wetting for Vibrational Energy Harvesting Applications

Piezoelectric polymers, capable of converting mechanical vibrations into electrical energy, are attractive for use in vibrational energy harvesting due to their flexibility, robustness, ease, and low cost of fabrication. In particular, piezoelectric polymers nanostructures have been found to exhibit higher crystallinity, higher piezoelectric coefficients, and “self‐poling,” as compared to films or bulk. The research in this area has been mainly dominated by polyvinylidene fluoride and its copolymers, which while promising have a limited temperature range of operation due to their low Curie and/or melting temperatures. Here, the authors report the fabrication and properties of vertically aligned and “self‐poled” piezoelectric Nylon‐11 nanowires with a melting temperature of ≈200 °C, grown by a facile and scalable capillary wetting technique. It is shown that a simple nanogenerator comprising as‐grown Nylon‐11 nanowires, embedded in an anodized aluminium oxide (AAO) template, can produce an open‐circuit voltage of 1 V and short‐circuit current of 100 nA, when subjected to small‐amplitude, low‐frequency vibrations. Importantly, the resulting nanogenerator is shown to exhibit excellent fatigue performance and high temperature stability. The work thus offers the possibility of exploiting a previously unexplored low‐cost piezoelectric polymer for nanowire‐based energy harvesting, particularly at temperatures well above room temperature.     

A Mobile App Search Engine

With the popularity of mobile apps on mobile devices based on iOS, Android, Blackberry and Windows Phone operating systems, the numbers of mobile apps in each of the respective native app stores are increasing in leaps and bounds. Currently there are close to one million mobile apps across these four major native app stores. Due to the enormous number of apps, both the constituents in the app ecosytem, consumers and app developers, face problems in ‘app discovery’. For consumers, it is a daunting task to discover the apps they like and need among the huge number of available apps. Likewise, for developers, enabling their apps to be discovered is a challenge. To address these issues, Mobilewalla (MW) an app search engine provides an independent unbiased search for mobile apps with semantic search capabilities. It has also developed an objective scoring mechanism based on user and developer involvement with an app. The scoring mechanism enables MW to provide a number of other ways to discover apps—such as dynamically maintained ‘hot’ lists and ‘fast rising’ lists. In this paper, we describe the challenges of developing the MW platform and how these challenges have been mitigated. Lastly, we demonstrate some of the key functionalities of MW.     

Designing a green optical network unit using ARMA-based traffic prediction for quality of service-aware traffic

The optical access networks (OANs) provide an attractive solution to the bandwidth bottleneck problem of the last mile. However, it has been proved (Baliga et al. in J Lightwave Technol 27(13):2391–2403, 2009; Baliga et al. in IEEE Commun Mag 49(6):70–77, 2011) that the OAN consumes a significant ratio of the total energy consumed in an optical networking scenario. This has provided incentive for inspection of energy-efficient schemes for OANs. It has been demonstrated in the literature that energy consumption figures of an OAN can be improved by either designing efficient hardware or employing better media access control (MAC) protocols. In this paper, we design a MAC protocol for OANs to ensure energy-efficiency in the presence of quality of service (QoS)-aware traffic. The proposed scheme incorporates traffic prediction-based selection of different sleep (energy-efficient) modes of operation, of the optical network units—ONUs (OAN end units). It also implements switching between different sleep modes to maintain high QoS with significant energy-efficiency figures. The discussed scheme requires processing at the ONU only and can work independent of the entire OAN (ONU assisted). Thus, our proposal is an attractive solution for the already deployed networks or even in green field deployment.     

Research issues in genomic signal processing

Genomic signal processing (GSP) concerns the processing of genomic signals. It may be defined as the analysis, processing, and use of genomic signals to gain biological knowledge and the translation of that knowledge into systems-based applications. In this article, the authors discuss the key research issues for GSP. It is important to recognize that "genomic signal processing" is not a name for genomic bioinformatics nor for the application of signal processing methods in genomics. We note that the research issues pertaining to GSP fit within the overall challenges confronting research in the area of multimodal biomedical systems.     

Modeling of nonideal volume Bragg reflection gratings in photosensitive glass using a perturbed transmission matrix approach

Reflection spectra of volume Bragg gratings written in bulk photosensitive silicate glass for wavelength division multiplexing applications are modeled using a transmission matrix approach. This allows for the examination of the effects of spatial perturbations along the grating due to chirp, apodization, compositional inhomogeneities, and index contrast saturation leading to reflection spectra that are asymmetric about the Bragg peak. Effects of the nonlinear relationship between index contrast in the glass and exposure flux on the reflection spectrum is also studied. Volume Bragg gratings are fabricated in UV exposure-sensitive silicate glasses containing alkali-halide nano-crystalline domains, and their reflection spectra are compared with calculation. The magnitude and uniformity of the index changes observed in our glass gratings make them useful in a wide range of wavelength multiplexing applications.     

An algorithm for optimal assignment of a wavelength in a tree topology and its application in WDM networks

In this paper, we present a polynomial time algorithm that gives an optimal solution to the routing and wavelength assignment (RWA) problem in a tree topology. One of the major design issues in wavelength-division multiplexed networks is the assignment of the limited number of wavelengths among network stations so that greater capacity can be achieved. The problem of RWA is known to be NP-hard problem. Many researchers have tackled the problem of RWA with a number of efficient heuristic algorithms. This paper presents an algorithm that optimally assigns a single wavelength to maximize one-hop traffic in a tree topology. The algorithm uses dynamic programming and is shown to be optimal with a time complexity of O(N/sup 4/). We also propose a heuristic scheme to use our optimal algorithm for wavelength assignment in a general graph. The heuristic works on the tree subgraphs of a given graph and the remaining spare wavelengths can be assigned with an existing RWA policy.