Electronics

This paper present the design of cantilever-based biosensors with new readout, which hold promises as fast and cheap “point of care” device as well as interesting research tools. The fabrication process and related issues of the cantilever based bio-sensor are discussed. Coventorware simulation is carried out to analyze the device behavior. A fully integrated control circuit has been designed to solve manufacturing challenge which will take care of positioning of the cantilever instead of creating nanometer gap between the electrodes. The control circuit will solve the manufacturing challenge faced by the readout methods where it is essential to maintain precise gap between the electrodes. The circuit can take care of variation obtained due to fabrication process and maintain the precise gap between the electrodes by electrostatic actuation. The control circuit consist of analog and digital modules. The reliability issues of the sensor are also discussed.

Si quantum dots-based structures are studied recently for performance enhancement in electronic devices. This paper presents an attempt to get high density quantum dots (QDs) by low pressure chemical vapour deposition (LPCVD) on SiO 2 substrate. Surface treatment, annealing and rapid thermal processing (RTP) are performed to study their effect on size and density of QDs. The samples are also studied using Fourier transformation infrared spectroscopy (FTIR), atomic force microscopy (AFM), scanning electron microscopy (SEM) and photoluminescence study (PL). The influence of Si-OH bonds formed due to surface treatment on the density of QDs is discussed. Present study also discusses the influence of surface treatment and annealing on QD formation.

We have investigated gate oxide degradation as a function of high-field constant current stress for two types of oxides, viz. standard dry and LPCVD oxides. Charge injection was done from both electrodes, the gate and the substrate. Our results indicate that compared to dry oxides, LPCVD oxides show reduced charge trapping and interface state generation for inversion stress. The degradation in LPCVD oxides with constant current stress has been explained by the hydrogen model.

High-field effects in metal-oxide-semiconductor capacitors have been studied in detail. A comprehensive set of experiments, stressing identically fabricated capacitors on both P-type and \ N-type silicon, both in accumulation and in inversion, has been made to study defect generation in the oxide at high fields. There is clear experimental evidence that both bulk hole and electron traps are generated under all stress conditions. High-field prebreakdown properties depend mainly upon the dynamics of generation of traps, trapping and detrapping at these and in previously existing traps. It has been found that of several processes, some dominate, depending upon the type of silicon and polarity during stressing, and this is also true for the final breakdown mechanism. In this paper the dominant mechanisms are identified for each of the field stress conditions that have been studied.

Degradation of the gate oxide is often studied by stressing of metal-oxide-semiconductor (MOS) capacitors. Usually the MOS capacitor is stressed in accumulation to avoid the complications due to a voltage drop across the depletion layer if stressed in inversion. High field stressing studies for MOS capacitors with the silicon in inversion are presented in this article. Our observations show that in this mode, silicon properties (mainly minority carrier generation lifetime) play an important role.

Gallic acid (GA) is important for pharmaceutical industries as an antioxidant. It also finds use in tanning, ink dyes and manufacturing of paper. Molecularly imprinted polymers (MIP), which are tailor made materials, can play an excellent role in separation of GA from complex matrices. Molecular recognition being the most important property of MIP, the present work proposes a methodology based on density functional theory (DFT) calculations for selection of suitable functional monomer for a rational design of MIP with a high binding capacity for GA. A virtual library of 18 functional monomers was created and screened for the template GA. The prepolymerization template-monomer complexes were optimized at B3LYP/6-31G(d) model chemistry and the changes in the Gibbs free energy (ΔG) due to complex formation were determined on the optimized structures. The monomer with the highest Gibbs free energy gain forms most stable complex with the template resulting in formation of more selective binding sites in the polymeric matrix in MIPs. This can lead to high binding capacity of MIP for GA. Amongst the 18 monomers, acrylic acid (AA) and acrylamide (AAm) gave the highest value of ΔG due to complex formation with GA. 4-vinyl pyridine (4-Vp) had intermediate value of ΔG while, methyl methacrylate (MMA) gave least value of ΔG due to complex formation with GA. Based on this study, the MIPs were synthesized and rebinding performance was evaluated using Langmuir-Freundlich model. The imprinting factor for AA and AAm based MIPs were 5.28 and 4.80 respectively, 4-Vp based MIP had imprinting factor of 2.59 while MMA based MIP exhibited an imprinting factor of 1.95. The experimental results were in good agreement with the computational predictions. The experimental data validated the DFT based computational approach.

Reliability is a very important concern for the embedded systems. Thermal distribution has become an important reliability concern for today's integrated circuits and these circuits are being used increasingly in embedded systems. In traditional design flows, the temperature of the chip is assumed to be uniform across the substrate. However, nonuniform thermal distribution can be a major source of inaccuracy in delay and clock skew computations, and can have an impact on elctromigration reliability and self-heating effects for today's very deep submicron technology. Hence, it has become necessary to obtain design with uniform temperature distribution to ensure minimum temperature gradient and avoid hot spots across the chip area. This will minimise reliability problems during the operation of the chip. The uniform temperature distribution can be achieved by appropriate placement of circuit blocks during the physical design. In this paper, thermal distribution of single chip embedded system on silicon is discussed. The thermal distribution calculations require evaluation of switching activity factor of circuit blocks. This factor is determined by computing activities of the blocks based on the application software of embedded system.

The Network-on-Chip (NoC) is Network-version of Systemon-Chip (SoC) means that on-chip communication is done through packet based networks. In NOC topology, routing algorithm and switching are main terminology .The routing algorithm is one of the key factor in NOC architecture. The routing algorithm ,which defines as the path taken by a packet between the source and the destination .As XY routing algorithm mainly used in NOC because of its simplicity. This paper basically review of XY routing algorithm in which we study a different type of XY routing algorithm. The classification of XY routing algorithm is totally depend upon the environment and requirement. Such that IX/Y routing algorithm is for less collision in network, for deadlock-free and livelock-free DyXY is used, for fault-tolerant XYX routing algorithm is proposed and Adaptive XY routing algorithm is used for fully utilization of network resource.

A stable, multiple energy domain and multi scale simulation tool for Microsystems is developed. A structured design methodology is adopted for design and optimization of RF MEMS shunt switch and MEMS inductor. The CAD tool developed is a device specific and incorporates physical parameters such as surface roughness. The tool analyzes the impact of surface roughness and also does thermal analysis. These are useful for understanding reliability and failure mechanisms of RF MEMS components.

Grid computing is a means of allocating the computational power of a large number of computers to complex difficult computation or problem. Grid computing is a distributed computing paradigm that differs from traditional distributed computing in that it is aimed toward large scale systems that even span organizational boundaries. We propose a novel method to achieve maximum fault tolerance in the Grid environment system by using Reliability consideration.

A stable, device specific, multiple energy domain and multi scale simulation tool for Radio Frequency (RF) MicroElectroMechanicalSystems (MEMS) devices is developed. A structured design methodology is adopted for design and optimization of RF MEMS shunt switch and MEMS inductor. The Computer Aided Design (CAD) tool incorporates physical parameters such as surface roughness. An electro- mechanical model of the RF MEMS

Summary Network-on-Chip (NoC) is a new paradigm for designing core based System-on-Chip. Network-on-Chip has been proposed as a solution for addressing the design challenges of future high performance nanoscale architectures. Innovative system-level performance models are required for designing NoC based architectures. In this paper, we discuss the possibility of achieving the energy-aware NoC architecture based on the mathematical notion of

The emphasizes on higher data rates and spectral efficiency has driven the industry towards linear modulation techniques such as QPSK, 64 QAM, or multicarrier configurations. The result is a signal with a fluctuating envelope which generates intermodulation (IM) distortion from the power amplifiers. Since most of the IM power appears as interference in adjacent channels, it is important to use a highly linear power amplifier. This paper describes a new approach of using a Diode as a predistorter in view of minimizing non linear distortion introduced by the high power amplifier in microwave radio links. The approach is based on preventing the base-collector junction from becoming forward biased also preventing VDS > VGS-Vt in case of MOSFETs / pHEMTs. This approach has two advantages 1) It prevents the transistor to go into saturation 2) Reduces the effect of nonlinear terms generated by the active device.

The deployment of MicroElectroMechanical System (MEMS) cantilever in the electronic systems is continuously increasing. These devices are usually interfaced with electronic circuits. It is important to build its macro model for rapid system design and simulation. This paper proposes development of an electromechanical coupling macro model of electrostatically actuated MEMS cantilever for straight and curled beam configurations. It consists of linear electrical components and nonlinear dependent sources, which represent mechanical parameters and electromechanical coupling in the system. In order to model device mechanics, analytical formulations are done and calculations are adapted to macro model. A methodology to derive electromechanical coupling as a function of bias voltage is developed. This electrical model is capable of predicting the device characteristic behaviour before the onset of pull-in instability region and estimates pull-in voltage. Such macro model can be easily implemented in any circuit simulation platform and be used to demonstrate the possible advantage of using this scheme for device and system dynamics optimization. To arrive at equivalence, an analytical formulation for spring constant and pull-in voltage of cantilever based on the partial load distribution and curling is derived. It utilizes the methodology based on nonlinear electrostatic pressure approximated by its linearized uniform counterpart and mechanical forcedeflection model. An electrical characterization of fabricated MEMS cantilever is done to obtain the experimental value of pull-in voltage. Simulation Program with Integrated Circuit Emphasis (SPICE) simulations results for the developed model is obtained for actual device dimensions and is in good agreement with analytical and experimental results.

Biosensors can be used to detect the microorganisms present in water [1], [2]. This paper presents a method to detect E.coli bacteria in water depending upon the capacitance modulation in the presence and absence of E.coli cell, which is simulated in Comsol Multiphysics (ver-3.5). Debye layer and cell wall effects [Figure 6, 7, 8] can also be observed using this method. It also presents the simulated results of change in capacitance with microorganism moving with fluid flow [Figure 9].Results show that capillary force is suffices for flow of E.Coli flow with water.

A simple and compact model is derived for the n-well resistor. The model was derived speci®cally for use in simulation and design of ESD protection circuits using SPICE. Hence it encompasses three regions of resistor operation: linear and velocity saturation, avalanche multiplication and snapback and high injection. Excellent ®t with experimental data is found.

Polymer microelectromechanical system (MEMS) devices emerge as the new class of sensor devices for bio-sensing applications exhibiting high mechanical deformability and sensitivity. In this work, the design and fabrication of electrostatically actuated polydimethylsiloxane (PDMS) MEMS cantilever on flexible PDMS substrate is presented. The physical parameters of the cantilever were analysed and optimised using Taguchi method coupled with COMSOL Multiphysics software. This work focusses on the development of a novel approach for the simple and cost-effective fabrication process of PDMS cantilevers and subsequently its arrays. The proposed device consists of a PDMS body with the metal bottom electrode, PDMS anchor, and PDMS cantilever beam as its top electrode and immobilization surface. The work presented is of the cracking phenomenon in the metal layer sputtered on the PDMS substrate. The novelty of the fabrication process is the use of low-cost processes, no need for sophisticated lithography tools or etching equipment. Also, the process allows the use of alternate material as base substrate (glass, silicon wafer etc.) wherein it is not consumed and is reusable. The fabricated device is then electrically characterised for its pull-in characteristics.