SPICE (Simulation Program with Integrated Circuit Emphasis)

Circuit simulation is a technique to predict the behavior of a real circuit using a computer program. It replaces real components with predefined electrical models. It is not possible to conceder all the physical processes (in circuit level simulation) in the parts and all PCB parasitic so it will only reflect the specific model that is put into it. This is the reason behind that simulators can’t substitute bread boarding and prototyping. But they allow measurements of internal currents, voltages and power that in many cases are virtually not possible to do any other way.

SPICE (Simulation Program with Integrated Circuit Emphasis) is a general-purpose open source analog electronic circuit simulator. It is a powerful program that is used in integrated circuit and board-level design to check the integrity of circuit designs and to predict circuit behavior.

Integrated circuits, unlike board-level designs composed of discrete parts, are impossible to breadboard before manufacture. Further, the high costs of photo lithographic masks and other manufacturing prerequisites make it essential to design the circuit to be as close to perfect as possible before the integrated circuit is first built. Simulating the circuit with SPICE is the industry-standard way to verify circuit operation at the transistor level before committing to manufacturing an integrated circuit.

Board-level circuit designs can often be bread boarded for testing. Even with a breadboard, some circuit properties may not be accurate compared to the final printed wiring board, such as parasitic resistances and capacitance. These parasitic components can often be estimated more accurately using SPICE simulation. Also, designers may want more information about the circuit than is available from a single mock-up. For instance, circuit performance is affected by component manufacturing tolerances. In these cases it is common to use SPICE to perform Monte Carlo simulations of the effect of component variations on performance, a task which is impractical using calculations by hand for a circuit of any appreciable complexity.

Circuit simulation programs, of which SPICE and derivatives are the most prominent, take a text netlist describing the circuit elements (transistors, resistors, capacitors, etc.) and their connections, and translate this description into equations to be solved. The general equations produced are nonlinear differential algebraic equations which are solved using implicit integration methods, Newton’s method and sparse matrix techniques

SPICE was developed at the Electronics Research Laboratory of the University of California, Berkeley by Laurence Nagel with direction from his research advisor, Prof. Donald Pederson. SPICE1 was largely a derivative of the CANCER program, which Nagel had worked on under Prof. Ronald Rohrer. CANCER was an acronym for “Computer Analysis of Nonlinear Circuits, Excluding Radiation,” a hint to Berkeley’s liberalism of 1960s: at these times many circuit simulators were developed under the United States Department of Defence contracts that required the capability to evaluate the radiation hardness of a circuit. When Nagel’s original advisor, Prof. Rohrer, left Berkeley, Prof. Pederson became his advisor. Pederson insisted that CANCER, a proprietary program, be rewritten enough that restrictions could be removed and the program could be put in the public domain.

SPICE1 was first presented at a conference in 1973. SPICE1 was coded in FORTRAN and used nodal analysis to construct the circuit equations. Nodal analysis has limitations in representing inductors, floating voltage sources and the various forms of controlled sources. SPICE1 had relatively few circuit elements available and used a fixed-time step transient analysis. The real popularity of SPICE started with SPICE2 in 1975. SPICE2, also coded in FORTRAN, was a much-improved program with more circuit elements, variable time step transient analysis using either the trapezoidal (second order Adams-Moulton method) or the Gear integration method (also known as BDF), equation formulation via modified nodal analysis (avoiding the limitations of nodal analysis), and an innovative FORTRAN-based memory allocation system developed by another graduate student, Ellis Cohen. The last FORTRAN version of SPICE was 2G.6 in 1983. SPICE3 was developed by Thomas Quarles (with A. Richard Newton as advisor) in 1989. It is written in C, uses the same netlist syntax, and added X Window System plotting.

As an early open source program, SPICE was widely distributed and used. Its ubiquity became such that “to SPICE a circuit” remains synonymous with circuit simulation. SPICE source code was from the beginning distributed by UC Berkeley for a nominal charge (to cover the cost of magnetic tape). The license originally included distribution restrictions for countries not considered friendly to the USA, but the source code is currently covered by the BSD license.

SPICE inspired and served as a basis for many other circuit simulation programs, in academia, in industry, and in commercial products. The first commercial version of SPICE was ISPICE, an interactive version on a timeshare service, National CSS. The most prominent commercial versions of SPICE include HSPICE (originally commercialized by Shawn and Kim Hailey of Meta Software, but now owned by Synopsys) and PSPICE (now owned by Cadence Design Systems). The academic spinoffs of SPICE include XSPICE, developed at Georgia Tech, which added mixed analog/digital “code models” for behavioural simulation, and Cider (previously CODECS, from UC Berkeley/Oregon State Univ.) which added semiconductor device simulation. The integrated circuit industry adopted SPICE quickly, and until commercial versions became well developed many IC design houses had proprietary versions of SPICE. Today a few IC manufacturers, typically the larger companies, have groups continuing to develop SPICE-based circuit simulation programs. Among these are ADICE at Analog Devices, LTspice at Linear Technology, Mica at Freescale Semiconductor, and TISPICE at Texas Instruments. (Other companies maintain internal circuit simulators which are not directly based upon SPICE, among them PowerSpice at IBM, Titan at Qimonda, Lynx at Intel Corporation, and Pstar at NXP Semiconductor.)

SPICE became popular because it contained the analyses and models needed to design integrated circuits of the time, and was robust enough and fast enough to be practical to use. Precursors to SPICE often had a single purpose: The BIAS program, for example, did simulation of bipolar transistor circuit operating points; the SLIC program did only small-signal analyses. SPICE combined operating point solutions, transient analysis, and various small-signal analyses with the circuit elements and device models needed to successfully simulate many circuits.

Some of the popular circuit simulators are as follows:

1.            ASTAP

2.            Advanced Design System

3.            CircuitLogix

4.            CPU Sim

5.            GNU Circuit Analysis Package

6.            Gpsim

7.            ICAP/4

8.            List of free electronics circuit simulators

9.            Logisim

10.          Micro-Cap

11.          NI Multisim

12.          National Instruments Electronics Workbench Group

13.          Ngspice

14.          PSpice

15.          PowerEsim

16.          Quite Universal Circuit Simulator

17.          SPICE

18.          SapWin

19.          SmartSpice

20.          SNAP (software)

21.          Spectre Circuit Simulator

22.          SpectreRF

These simulators differs each other and are generally application specific. Most popular version of spice simulators for analog circuit simulations are PSpice offered by MicroSim but now incorporated in OrCAD of Cadence and National Instruments Multisim.

“Do Bussiness with Style” cool new templates for Microsoft office 2007

Are u get bored using traditional old Microsoft office environment ,then here is something new. Microsoft Small Business is now giving out some cool free designer templates for Office 2007 for Windows, and Office 2008 for Mac. The best is that they comes in 9 colour schemes. These six templates contain a spreadsheet, presentation, invoice, letterhead, business card and newsletter blast templates.U can also get a 60 days free trial of Microsoft Office if you don’t have it. just click the link

Microsoft Office 2007 free templates

Don’t forget that , these templates will only work if you have the Office (2007 for Windows and 2008 for Mac) because the templates are in the new formats (.docx, .xlsx etc.). These templates are zip files and you can download them directly. No verification required.

List of Approved Post Graduate Education and Research institutions for M Tech & M E

Here is a link having information of seats of M Tech and M E in various colleges in India , although the document is little bit older but will be very helpful for basic idea of available courses and information about seats. click the link bellow to download the document.

List of Approved Post Graduate Education and Research institutions Upto 30th September, 2004 (M.E/M.Tech)

Save Energy Go green

Not with envy, but kindness to the environment, and alertness to your electricity bills

You leave your PC on all day. But you care for the environment, so you switch off the monitor. Good move, but did you know you are still wasting about 45 Watts with the CPU running?

That’s what Tufts University’s Climate Initiative says. And it also says that if you leave your PC on for the entire day, 850-1500 pounds of carbon dioxide is released into the atmosphere a year. And this means that you need 60-300 trees to absorb that much CO2 in a year.

That does get you thinking doesn’t it! Now, all that noise about climate change because of our insensitivity to the environment starts to make sense. We cut down trees, we waste electricity, we replace cellphones and gadgets with the latest ones, without bothering about what really happens to the old ones. While there could be debates on how much all this really impacts our environment, most of us know intuitively that what we are doing mindlessly is really not right, and is likely to have negative repercussions.

That is why the world over, the word Green is becoming red hot. Green computing is in. This means that you start to use computing resources efficiently. It’s not just about being good to Mother Nature, but also being able to save a lot of money being spent on electricity. For companies that have thousands and thousands of computers running, datacenters keeping their businesses up and running, all this can add to a huge fortune. In fact, going green is now gaining so much momentum that those companies which do not have green computing initiatives are seen as enemies of the environment.

So how does it matter to you? You might have one PC and a laptop at home, in addition to the multiple electronic devices you run. And you might even be considering another PC for the little one. Think if you really need all those PCs. Buy only if you have to. While buying, remember that laptops consume less power, so it could be wiser to go the portable way. Or if you need to look at a PC, opt for monitors that consume less power. LCD monitors need much less power than CRT ones. Look for Energy Star ratings and save energy.

Explore the power saving options of your PC and customize them to suit the way you work. If you often go away from your PC for a long time, you can set the monitor and hard disk to be switched off after a few minutes of no-activity.

To dispose old PCs and gadgets, get in touch with NGOs working in this area and figure out the best way to do so. Or if you own a branded PC or gadget, get in touch with the company and ask how this e-waste can be managed. Most computer vendors and cellphone makers have Green initiatives on, so you might get some help.

These are still early days for green initiatives for companies in India. But if you and I make a start, the rest will fall in place.

ISRO all set for Chandrayan II in 2012, Mars mission in 2013

24 December 2008
Indian Space Research Organisation (ISRO) is all set for its second moon mission `Chandrayaan II’ and space scientists plan to send a robot to moon in 2012, followed by a spacecraft to Mars in 2013.

ISRO will also sent a man to space astride a Russian spaceship the same year, its chairman G Madhavan Nair said.

Besides, ISRO has lined up a slew of missions, which also include landing a spacecraft on an asteroid and sending a probe to fly past a comet, the ISRO chief told reporters at a function organised by the Confederation of Indian Industry (CII) to felicitate the members of the Chandrayaan I team.

”Chandrayaan II, the design is complete, we hope by 2012, we will be ready for the launch,” Madhavan Nair said.

The launch of Chandrayaan-II, approved by the government will include a rover that will land on the moon. It will map a three-dimensional atlas of the moon, and analyse the chemical and mineral composition of the lunar surface.

India hopes to send an astronaut into space by 2013 and a manned mission to the moon by 2020.

India, which started its space programme in 1963, now account for around 16 satellites currently in earth orbit

India also has the world’s largest constellation of seven earth-observation satellites, which is being used for telecommunications, TV broadcasting, earth observation, weather forecasting, remote education and healthcare.

Nair, however, said the mission to Mars is still at a conceptual stage and ISRO expects to finalise plans by next year, with take-off in 2013.b He said the same Geosynchronous Satellite Launch Vehicle (GSLV) will be used to launch the probe to Mars.

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HISTORY of ” Programmable Logic Controler “

   

 Origin

The PLC was invented in response to the needs of the American automotive manufacturing industry. Programmable controllers were initially adopted by the automotive industry where software revision replaced the re-wiring of hard-wired control panels when production models changed. Before the PLC, control, sequencing, and safety interlock logic for manufacturing automobiles was accomplished using hundreds or thousands of relays, cam timers, and drum sequencers and dedicated closed-loop controllers. The process for updating such facilities for the yearly model change-over was very time consuming and expensive, as the relay systems needed to be rewired by skilled electricians. In 1968 GM Hydramatic (the automatic transmission division of General Motors) issued a request for proposal for an electronic replacement for hard-wired relay systems. The winning proposal came from Bedford Associates of Bedford, Massachusetts. The first PLC, designated the 084 because it was Bedford Associates’ eighty-fourth project, was the result. Bedford Associates started a new company dedicated to developing, manufacturing, selling, and servicing this new product: Modicon, which stood for MOdular DIgital CONtroller. One of the people who worked on that project was Dick Morley, who is considered to be the “father” of the PLC. The Modicon brand was sold in 1977 to Gould Electronics, and later acquired by German Company AEG and then by French Schneider Electric, the current owner. One of the very first 084 models built is now on display at Modicon’s headquarters in North Andover, Massachusetts. It was presented to Modicon by GM, when the unit was retired after nearly twenty years of uninterrupted service. The automotive industry is still one of the largest users of PLCs, and Modicon still numbers some of its controller models such that they end with eighty-four.  

Development

Early PLCs were designed to replace relay logic systems. These PLCs were programmed in “ladder logic”, which strongly resembles a schematic diagram of relay logic. Modern PLCs can be programmed in a variety of ways, from ladder logic to more traditional programming languages such as BASIC and C. Another method is State Logic, a Very High Level Programming Language designed to program PLCs based on State Transition Diagrams. Many of the earliest PLCs expressed all decision making logic in simple ladder logic which appeared similar to electrical schematic diagrams. The electricians were quite able to trace out circuit problems with schematic diagrams using ladder logic. This program notation was chosen to reduce training demands for the existing technicians. Other early PLCs used a form of instruction list programming, based on a stack-based logic solver.  

 Programming

Early PLCs, up to the mid-1980s, were programmed using proprietary programming panels or special-purpose programming terminals, which often had dedicated function keys representing the various logical elements of PLC programs. Programs were stored on cassette tape cartridges. Facilities for printing and documentation were very minimal due to lack of memory capacity. The very oldest PLCs used non-volatile magnetic core memory.  

 Functionality

The functionality of the PLC has evolved over the years to include sequential relay control, motion control, process control, distributed control systems and networking. The data handling, storage, processing power and communication capabilities of some modern PLCs are approximately equivalent to desktop computers. PLC-like programming combined with remote I/O hardware, allow a general-purpose desktop computer to overlap some PLCs in certain applications.  

 Suppliers

Well known PLC brands include Siemens, Allen-Bradley, IDEC, ABB, Mitsubishi, Omron, Honeywell, Schneider Electric, Saia-Burgess Controls, and General Electric.

source:wikipedia.org

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STATE WISE INSTITUTES

 

CHANDRAYAAN-1 “INDIA’s MOON mission”

SRIHARIKOTA: On November 10 or 11, the national flag will be hoisted on the Moon. When the Moon Impact Probe (MIP), bearing the Tricolour, ejects from the Chandrayaan-1 spacecraft and crashlands on the lunar surface, it will mark India’s leap into the club of countries aiming for the Moon.“A small Indian flag (4 inches by six inches) has been painted on the moon impact probe. This is a matter of pride and honour, and when the MIP lands on the Moon, it will signal India’s entry into one of the intriguing aspects of the universe,’’ ISRO officials told TOI. 
The 29-kg MIP, which was not part of the project initially, was inducted into the spacecraft at the insistence of former President A P J Abdul Kalam. The payload developed by the Vikram Sarabhai Space Centre at Thiruvananthapuram will help identify future landing sites on the Moon and will also aid scientific exploration of the lunar surface. When the MIP crash-lands on the Moon, it will kick up dust. The mass spectrometer on the payload will gather scientific details from the dust and send them back to the earth. The MIP is one of the 11 payloads on Chandrayaan-I and one of the five instruments indigenously designed anddeveloped in India. 

On October 22, the PSLVC 11, also called PSLV-XL because of the increased weight of the six strap-on motors, will soar into the sky from the second launch pad at the Satish Dhawan Space Centre, Sriharikota . It will travel to the vicinity of the Moon by following the lunar transfer trajectory (LTT). 

When the spacecraft reaches the vicinity of the Moon, it will be slowed down through a process to enable the gravity of the Moon to capture it into its elliptical orbit. 

When the orbital height of Chandrayaan-I is lowered to its intended 100-km height from the lunar surface , the MIP will be ejected from Chandrayaan-I at the earliest on to the lunar surface in a chosen area. “About 20 days from the date of launch, Chandrayaan-I will be in the required Moon orbit. So we are looking at November 8, around noon,’’ SSDC director M C Dathan said. 

The spacecraft, which is being readied at another building , will be moved to the vehicle building by October 14, following which another four days of work will be carried out to couple Chandrayaan-1 with the launch vehicle. On October 18, the vehicle with the payloads will be moved to the launch pad. 

Dathan allayed fears of the launch not taking place on October 22 because of rains. “Only if a cyclone occurs will there be a problem. Otherwise, even with rains, the launch will take place,’’ he said.

 

 

Polymer electric storage

The proliferation of solar, wind and even tidal electric generation and the rapid emergence of hybrid electric automobiles demands flexible and reliable methods of high-capacity electrical storage. Now a team of Penn State materials scientists is developing ferroelectric polymer-based capacitors that can deliver power more rapidly and are much lighter than conventional batteries

 ”Electrical energy storage is very important for all electrical and electronic systems,” says Qing Wang, associate professor of materials science and engineering. “Even renewable energy systems like solar cells need somewhere to store excess energy to be used at night.” Wang and his research team report today (Aug. 20) at the 236th national American Chemical Society meeting in Philadelphia in two papers, on the development of power density tunable polymers and polymer ceramic nanocomposites as electric storage materials for capacitors. Currently, power conditioning is carried out by capacitors, but Wang believes that eventually properly tuned polymer capacitors could replace batteries. 

“Traditional materials are ceramic materials which have high weight and are very fragile,” says Wang. “Mobile electronics need light weight electrical energy storage.” 

See full-size image. .

The researchers, who include Wang, Yingying Lu, postdoctoral fellow, and Jason Claude, Junjun Li, graduate students in materials science and engineering, developed a polymer of poly(vinylidene fluoride) and trifluoroethylene which, with the addition of chlorotrifluoroethylene had a very high dielectric permittivity at room temperature. Permittivity is a measure of how much charge is stored in a material for a given electric field and is an indicator of how effective a material will be when storing energy in a capacitor. They found that by altering the amounts of the various chemical components of the polymer, they could tune the dielectric property and energy density. 

Hybrid cars are a good target for ferroelectric polymer capacitors because they convert mechanical energy generated when, for example coasting downhill, convert it to electricity and charge batteries for use at other times. Conventional batteries are often heavy, and may not be able to deliver the power amounts needed for quick acceleration. 

Wang and Li, report on a further modification of this ferroelectric polymer by adding nanoparticulate ceramics to further improve the energy density. Because ceramics often have higher permittivities than the polymers, they believed that combining polymers with high breakdown strength with ceramics of high permittivity would produce a composite material with a large energy storage capacity. Breakdown strength is a measure of the maximum electric field that an insulating material can withstand before it begins to conduct electricity. The higher the breakdown strength, the better a material is for a capacitor. 

Unfortunately mixing nano particles of ceramic with polymers is not a simple action. The ceramic particles tend to clump and aggregate. If the two materials are not matched for electrical properties, their interface will breakdown at high electric fields and the ability of the composite to store energy will decrease, rather than increase. Wang and his team fine-tuned the dielectric particles to the polymer matrix by adding functionalized groups to the materials to match them. They also tried to control the mixing so that uniformly dispersed particles are spread through the matrix. 

“Matching the permittivity and uniformly dispersing the ceramic nanoparticles is not easy,” says Wang. “Both problems have to be tackled and solved at the same time for the material to have the desired characteristics.” 

Dielectric polymers like the ones Wang creates cannot only be used as capacitors, but could also substitute for the dielectric silicon dioxide layer currently used in computers. Because polymers are processed at room temperature, they are easily fabricated and they are extremely flexible. Their use would open the way for flexible electronics applications, such as foldable screens and computers