Power conscious CAD tools and methodologies: a perspective

Power consumption is rapidly becoming an area of growing concern in IC and system design houses. Issues such as battery life, thermal limits, packaging constraints and cooling options are becoming key factors in the success of a product. As a consequence, IC and system designers are beginning to see the impact of power on design area, design speed, design complexity and manufacturing cost. While process and voltage scaling can achieve significant power reductions, these are expensive strategies that require industry momentum, that only pay off in the long run. Technology independent gains for power come from the area of design for low power which has a much higher return on investment (ROI). But low power design is not only a new area but is also a complex endeavour requiring a broad range of synergistic capabilities from architecture/microarchitecture design to package design. It changes traditional IC design from a two-dimensional problem (Area/performance) to a three-dimensional one (Area/Performance/Power). This paper describes the CAD tools and methodologies required to effect efficient design for low power. It is targeted to a wide audience and tries to convey an understanding of the breadth of the problem. It explains the state of the art in CAD tools and methodologies. The paper is written in the form of a tutorial, making it easy to read by keeping the technical depth to a minimum while supplying a wealth of technical references. Simultaneously the paper identifies unresolved problems in an attempt to incite research in these areas. Finally an attempt is made to provide commercial CAD tool vendors with an understanding of the needs and time frames for new CAD tools supporting low power design     

Minimal sensor integrity: Measuring the vulnerability of sensor grids

Given the increasing importance of optimal sensor deployment for battlefield strategists, the converse problem of reacting to a particular deployment by an enemy is equally significant and not yet addressed in a quantifiable manner in the literature. We address this issue by modeling a two stage game in which the opponent deploys sensors to cover a sensor field and we attempt to maximally reduce his coverage at minimal cost. In this context, we introduce the concept of minimal sensor integrity which measures the vulnerability of any sensor deployment. We find the best response by quantifying the merits of each response. While the problem of optimally deploying sensors subject to coverage constraints is NP-complete [Chakrabarty et al., IEEE Trans. Comput., to appear], in this paper we show that the best response (i.e., the maximum vulnerability) can be computed in polynomial time for sensors with arbitrary coverage capabilities deployed over points in any dimensional space. In the special case when sensor coverages form an interval graph (as in a linear grid), we describe a better O(min(M²,NM)) dynamic programming algorithm.     

A system-based component test plan for a series system, withtype-II censoring

Acceptance testing is analyzed for a series system of n components, each having an unknown, different, constant failure rate. Components are tested individually, and tests are terminated when a preassigned number of failures is observed for each component. The total time-on-test for each component is noted, and a statistic is constructed using observed test times and the number of failures of the components; the statistic is based on the maximum likelihood estimation of system reliability. This statistic is then used in specifying a decision rule for accepting or rejecting the entire system. The design of the test plan is stated as an optimization problem which minimizes test costs while ensuring that specified consumer and producer risks on system reliability are not exceeded. Numerical examples are provided, and implications of the test plan are discussed     

Selective synthesis of 3-picoline via the vapor-phase methylation of pyridine with methanol over Ni1-x Co x Fe2O4 (x = 0, 0.2, 0.5, 0.8 and 1.0) type ferrites

A series of Ni–Co ferrites with the general formula Ni_1-x Co _x Fe₂O₄ (x = 0, 0.2, 0.5, 0.8 and 1.0) was prepared by a low-temperature hydroxide coprecipitation route. The catalyst systems were characterized by adopting various physico-chemical techniques. Alkylation of pyridine with methanol was carried out in a down-flow vapor-phase reactor. The influence of surface acid–base properties, cation distribution in the spinel lattice and various reaction parameters are discussed. It was observed that the systems possessing x values 0.5 are selective for 3-picoline formation, whereas the ones with x values 0 and 0.2 give a mixture of 2- and 3-picolines. Pyridine conversion increased with the progressive substitution of Ni²⁺ ions by Co²⁺ ions. Cation distribution in the spinel lattice influences their acidic and basic properties, and these factors have been adequately considered as helpful to evaluate the activity of the systems.     

Modular operational test plans for inferences on softwarereliability based on a Markov model

This paper considers the problem of assessing the reliability of a software system that can be decomposed into a finite number of modules. It uses a Markovian model for the transfer of control between modules in order to develop the system reliability expression in terms of the module reliabilities. An operational test procedure is considered in which only the individual modules are tested and the system is considered acceptable if, and only if, no failures are observed. The minimum number of tests required of each module is determined such that the probability of accepting a system whose reliability falls below a specified value R₀ is less than a specified small fraction β. This sample size determination problem is formulated as a two-stage mathematical program and an algorithm is developed for solving this problem. Two examples from the literature are considered to demonstrate the procedure     

Design of high-order filters with restricted component values

The feasibility of realising a high-order LC filter with a small set of different capacitor values, without sacrificing the frequency response specifications, is indicated. This idea could be conveniently adopted in other filter structures also?for example the FDNR transformed filter realisations.     

Optimization of indoor wireless communication network layouts

Radio Frequency Data Communications (RFDC)technology is rapidly becoming a critical component of many traditional industrial engineering functions including materials tracking, inventory control, warehousing, order processing, shipping and database management. As a means of moving information, RFDC has many attractive features, such as speed, accuracy, reliability, convenience and low operating costs. When implementing RFDC systems a major problem is to quickly and efficiently determine the locations where transceivers should be placed so that effective radio communication can take place. The research described in this paper addresses this issue by developing a computerized layout simulation system that incorporates heuristic optimization methods to solve the placement problem. The effectiveness of this unique automated layout methodology is demonstrated by comparing it with the current method of utilizing manual site surveys, as well as with other placement methods. The methodology and solutions are validated by field-testing at actual facilities.     

Adaptive optimal tuning of a general class of stable LTI systems with restricted inputs

The problem addressed is one of model reference adaptive control (MRAC) of asymptotically stable plants of unknown order with zeros located anywhere in thes-plane except at the origin. The reference model is also asymptotically stable and lacking zero(s) ats = 0. The control law is to be specified only in terms of the inputs to and outputs of the plant and the reference model. For inputs from a class of functions that approach a non-zero constant, the problem is formulated in an optimal control framework. By successive refinements of the sub-optimal laws proposed here, two schemes are finally designed. These schemes are characterized by boundedness, convergence and optimality. Simplicity and total time-domain implementation are the additional striking features. Simulations to demonstrate the efficacy of the control schemes are presented. This paper is dedicated to Dr R M Umesh.