Tuesday, July 29, 2008

How to Learn Verilog?

In this article on how to learn verilog easily and efficiently in a very short time period. Before plunging into the details there are some basic requirements that is neccessary in going ahead with our exploration of Verilog language.

Verilog is a Hardware Description Language and so is basically used to model a hardware. Verilog is very much similar to C language and hence it is really very easy to capture the ideas even for a software programmer. In order to get started with the programming using Verilog language we need a verilog simulator hence one of the many simulators available like ModelSim, HDL Designer, Synapticad etc (Student versions)can be downloaded. We have just a step closer to learning verilog and the next step would be to download a choose a very simple book like Verilog Primer by J Bhasker, Verilog HDL by Samir Palnitkar or any verilog tutorial available on the web. Care has to be taken not to get a tougher book in the initial stages and getting into finer details. Our main important notion is to experiment with the language and hence as we go along when needed get into finer details.

Now we are prepared with the neccessary tools so we can go ahead in testing our new program by installing the simulator already downloaded. Many books start with history so you can skip all those and then move to the first program. Type in the same manner as printed or use the help file that is provided along with the simulator to know the basic components, features etc. Always start with a very simple model like AND gate, OR gate etc and move on to adders, subtractors etc. By doing this we can feel the confidence in our capability and hence we can learn enthusiastically in a very short time.

When all these steps are implemented you are ready to grasp more than what was mentioned previously hence now you are advised to go into finer details and check with the simulator. Happy learning Verilog Programming Language. You can also contact me if you some more help in dealing with the language. I would be glad to help you any time. In the mean time if you found this article helped you please leave a comment.

Book mark this page http://vlsitech.blogspot.com or leave a comment or suggestions to make further improvements.

VLSI Interview Questions- Part 4

1. What is rule of ten?

2. Define Noise Margin?

3. Design a controlled inverter?

4. Define Fan-in?

5. Why Open collector Outputs are provided in IC's?

6. What is meant by RoHS compliant?

7. Convert Octal(728) into decimal

8. An analog signal is sampled. What is the kind of signal now exist at the output of sampler?

9. A 10 bit ADC is given to sample a +/- 5V signal. What is resoulution of the ADC?

10. What is FIR? What is that which is finite?

11. What is difference between Glitch and Jitter?

12. What is the Latch up problem?

13. What are the timing components of a latch's clock and F/F?

14. Given 3 types of clocking ie Pulse mode clocking, Edge triggered clocking, Two Phase
Clocking which one do you chose and why?

15. Why is hold time negative sometimes and what does it signify?

Friday, July 25, 2008

VLSI Interview Questions - Part 3

What is Molecular beam epitaxy?

What is Scanning tunneling microscopy?

number of holes in a conducting metal?

Testing and verification difference

Defect Based Testing

What is yield loss?

what is Rent's rule?

GaAs is a piezo electric. Is it true?

How many lattices are there in a 3D crystal structure. explain?

How to achieve high throughput from a digital design?

Difference between Iterative and Pipelined implementation?

How to reduce latency in a Pipeline design?

What is the effect of removing pipeline registers in a design to latency?

How to calculate the Maximum frequency of the clock in a digital design(Sequential)?

What is Flatten Logic structure?

What is register balancing?

Define wander and Jitter?

Wednesday, July 23, 2008

VLSI Interview QUESTIONS(Part 2)

1. Write a stick diagram for basic gates

2. Define the parasitics present in a MOSFET

3. I V characteristics of a MOSFET?

4. Why is the current constant in a VI characteristics?

5. On increasing Vgs beyond threshold voltage there is a reduction in current using the normal diode equation why?

6. What is Channel Length Modulation?

7. Write a SPICE program for instantiating a MODEL of MOSFET?

8. What is Charge feedthrough?

9. What is transconductance and mention some features?

10. Metastability

11. How is Sensitivity of a Voltage reference defined?

12. What is thermal voltage and how much is the value?

13. Why is 0.7V the minimum voltage of a diode?

14. Draw CMOS amplifier characteristics?

15. What is ringing voltage?

16. A circuit with a FB diode and battery is wired. Where does the electrons and the holes flow in the circuit?

17. What is totoem pole arrangement. Why is it necessary?

18. What is 1/f Noise and how does the noise vary in PMOS and NMOS?

19. Design flow of a VLSI Design?

These questions are contributed by friends and many knowledgeable people across the globe. Their contributions are appreciated.


For ANSWERS do mail me

VLSI INTERVIEW QUESTIONS(part 1)

The questions listed below are some of the questions that were asked in VLSI interviews

1. What is Bird's beak?

2. Is there any negative frequency? If so what are its implications?

3. Why GaAs is advantageous over Silicon?

4. In fabrication GaAs cannot be everywhere why?

5. Why Gold is used during fabrication?

6. Why is Silicon used more than GaAs? (Technical points only)

7. Silicon's advantages over GaAs

8. State Moore’s law.

9. Design the 4:1 multiplexer circuit using TG switches.

10. Design a 4:1 mux using three 2:1 TG multiplexers.

11. Consider the 2-input XOR function.
a) Design an XOR gate using a 4:1 mux.
b) Modify the circuit in a) to produce a 2-input XNOR

12. Design a CMOS logic gate for the function f= a.b+a.c+b.d

13. Design a NAND3 gate using an 8:1 mux

14. Design a NOR3 gate using an 8:1 mux as a basis.

15. A sample of silicon is doped with arsenic with Nd = 4 x 1017 cm3. Find the majority carrier density, minority carrier density and calculate the electron and hole mobilities and then find the conductivity of the sample.

16 A region of silicon is doped with both phosphorus and boron. The p-doping is Nd = 2 x 1016 cm-3 while the B-doping level is Na =6 x 1018 cm-3. Determine the polarity(n or p) of the region, and find the carrier densities.

17. Four nFETs are used as pass transistor . The input voltage is set to Vin=Vdd=5V and it is given that Vth= 0.75V. Suppose that the signals are initially at (1,1,0,0) and are then switched to (0,1,1,1). Find the value of Vout.

18. Design a driver chain that will drive a load capacitance of CL =40pF , if the initial stage has an input capacitance of Cin =50fF.Use ideal scaling to determine the number of stages and the relative sizes.

19. Explain the DCcharacteristics of CMOS inverter

20. What is switched capacitance?

21. How switched capacitances are useful in design?

22. Use only 2:1 Mux to create a Full adder

23. Why should the testing be done?

24. Write S&H Equation?

25.Difference between MOSFET, MISFET, MESFET?

26. Which terminal in a transistor has the largest area? why?

27. Draw a current mirror circuit?

28. Define Slew Rate and CMRR in an Opamp and its characteristics?

29. Different A2D converters and advantages over the other?

30. CMOS advantages and disadvantages

31. What is Verilog and how is it useful?

32. VLSI simulation is given importance why?

33. How many terminals are present in a MOSFET? and define their characteristics?

34. Frequency spectrum ranges?

35. What is STA(Static timing Analysis)?

36. Where is NMOS used and why?

37. Draw capacitance curve of MOSFET?

38. What acid is used to remove Silicon Nitride?

39. What acid is used to remove Silicon DiOxide?

40. What is Dry Etching(Plasma Etching)?

41. What is SOI and mention its advantages?

42. What is LOCOS how is it different from normal techniques?

43. Threshold voltage and Body effect are related how?

The questions are contributed by friends, colleagues and WWW. All contributions are appreciated.
To get the ANSWERS do mail me.

Sunday, July 20, 2008

VLSI Seminars Topics

You can find many seminar articles on Automobiles, Electronics, Computer Science, Information Technology etc. Find Here....


STATIC TIMING ANALYSIS

ANALOG MEMORIES

NANO-RAM

ORGANIC LED

M-RAM(MAGNETO RESISTANCE RANDOM ACCESS MEMORY)

MULTI THRESHOLD CMOS

LOW LEAK TRANSISTOR

MESFET

SINGLE ELECTRON TUNNELING TECHNOLOGY

EXTREME ULTRA VIOLET LITHOGRAPHY

MEMS (MICRO ELECTROMECHANICAL SYSTEMS)

PHOTONIC INTEGRATION OF HYBRID SILICON

THESE SEMINAR TOPICS ARE CONTRIBUTED BY FRIENDS FROM VARIOUS INSTITUTES. THE BLOG OWNER THANKS THEM WHOLE-HEARTEDLY.

LOOKING FOR GOOD ARTICLES AND THEIR CONTRIBUTION WOULD BE RECOGNISED.

Tuesday, July 15, 2008

VLSI Articles

Articles which were found best for a VLSI beginner are listed below. Links are provided to read the full article.

Latest Articles

Three dimensional Chip Design
The three dimensional (3-D) chip design strategy exploits the vertical dimension to alleviate the interconnect related problems and to facilitate heterogeneous integration of technologies to realize system on a chip (SoC) design. By simply dividing a planar chip into separate blocks, each occupying a separate physical level interconnected by short and vertical interlayer interconnects (VILICs), significant improvement in Read more...

Intel, AMD... Why not more?

Why is it that the CPU market has so few players? Is it entirely a practical, technical issue of getting a physical plant up and running? What's more to the precious "CPU space"? Why can't we see more competition than just the Intel and AMD that we have now? Read More

Demand for engineering talent to double

The semiconductor industry in India is growing at a scorching pace of 25% against the global average of around 5% every year. The long-term prospects too look encouraging with government chipping in to support the industry. Read More...

Solar, Semiconductor Project Proposals Worth Rs.80,000 Cr. Await Indian Govt. Nod
The Special Incentive Package Scheme or SIPS, notified last year by the Indian Government to encourage investments in semiconductor fabrication and other micro and nano technology manufacturing industries, has attracted nearly a dozen proposals together worth Rs.80,000 crores that include corporate giants like Reliance Industries, Videocon and Tata BP Solar, the media reported. Read More...

Hynix to Produce Semiconductors for Vehicles
Hynix Semiconductor, the world's No. 2 dynamic random access memory (DRAM) chip manufacturer, has secured another springboard Monday to spur its strategic contract-based foundry business by forming a tie-up with a local fabless company.

Hynix said it has signed a binding agreement to buy a 5 percent stake in C&S Technology for 4.5 billion won ($4.5 million) and jointly develop semiconductors used in automobiles. Read More...


Monday, July 14, 2008

VLSI Text Books

Semiconductor Device Physics and Design --> UMESH K. MISHRA & JASPRIT SINGH

CMOS Digital Integrated Circuits: CMOS Digital Integrated Circuits by Sung Mo Kang and Yusuf Lebelci

DSP: DSP by Proakis and Signals and systems by Simon Haykin(Reference)

Maths: Do not purchase any book, Use the books which were used in BTech and utilise the library

Digital Hardware Modelling: Verilog HDL by Samir Palnitkar

Solid State Devices: Professor follows Jasprit Singh and StreetMan(good) but you can use the book by Sima djimitrijev and Donand Neaman, Anderson for better understanding. But referring too many books may confuse the terminologies so kindly follow a single book.

Advanced FPGA Design ---> Steve Kilts

Silicon Processing for the Vlsi Era: Process Technology --> Stanley Wolf and Richard N Tauber

Silicon-On-Insulator Technology: Materials to Vlsi --> Jean-Pierre Colinge

Silicon Wafer Bonding Technology for Vlsi and Mems Applications

Computer Aids for VLSI Design

Design of VLSI Systems

Introduction to VHDL by Peter J. Ashenden

Verilog synthesis Interoperability 1364.1 a standards draft document

Application Specific Intergrated Circuits By Michael John Sebastian Smith

Contemporary Logic Design by
Randy H. Katz, University of California, Berkeley

The Scientists and Engineers's Guide to DSP

Digital Systems design with FPGA's by Ion Grout

More Books can be found here

Saturday, July 12, 2008

VLSI Projects

VLSI field is capital intensive hence project in this field is little, only design implementation in the software. Once everything works fine and the design is practically feasible then we may look for Fabrication. But as a starting point many students use IEEE papers and try to simulate the results obtained, Intellectual Property(IP) cores, Simulation of a design using IP Cores, Physical implementation of Small circuits etc.

Example of Project Ideas

Interconnect Models

Physical Layout implementation of Different kind of adders, multipliers and their comparisions.

Microprocessor core generation

(DSP) Algorithm Implementation etc

Protocol Implementation like CAN, AMBA

Try to visit a University website and you may find many projects which are done. Many times ideas, their implementation would be found and if you are lucky may end up with the design code.

But my suggestion would be not to take any project just like that and show it instead try to add your own design and see the change in this way you will be helping the field and you would gain confidence once you are in job.

If you need any help on a project please contact me. If I am able to help I would be glad to do it.


I would be glad to make projects for you, for some small payment.

Some of the VLSI Institutes

The list provided is only what I came up with. You may help me in adding some more institutes to this list.

Bit mapper PUNE

VEDAIIT Hyderabad

Sandeepani Hyderabad & Bangalore

Accel Technologies Chennai

VEDANT Chandigarh(Now part of ISRO)

Maintec Bangalore

PICT SITM Pune

SSI Chennai

Horizon Semiconductors & Networking Solutions Chennai

CMC Limited, Centre Of Excellence in IT Kochi

ATIIT (P) LTD Chennai

Career Avenues Bangalore

UTL Technologies Ltd Bangalore

REAL TIME EMBEDDED AND VLSI LABS Chennai

Trident Techlabs Pvt. Ltd. Pune

Teknowedge Quality Management Services Pvt.Ltd Bangalore

HI-TECH END Mumbai

MindstormGlobalTechnologies Chennai

SIMSHODH Bangalore

ISRDO Delhi

Courtesy of many other VLSI Websites for this comprehensive list.

VLSI Softwares

Cadence, Synopsys, Mentor Graphics are the major EDA software tool vendors. Xilinx, Altera, Actel holds the major market share in FPGA/CPLD. Most of the FPGA Vendors have their own EDA Tool to program their FPGA/CPLD or products.

Simulators(Verilog and VHDL)

ModelSim® SE

HDL Designer

Cadence NC

Iverilog

Synthesis tools

Precision RTL

Leonardo Spectrum

FPGA Advantage


Physical Design tools

Tanner

MAGIC Layout Editor

Alliance CAD Tools

OCEAN
& nbsp; Irsim

Gtkwave

PSPICE / Hspice


Free VLSI Tools

MAGIC Layout Editor

Alliance CAD Tools

OCEAN

Iverilog

Irsim

Gtkwave

ISE Webpack

FPGA Development

Xilinx ISE™ WebPACK™ Software

Altera Quartus® II Software


Physical Design tools list are yet to be added

The List does not stop here. Many new companies are emerging and hence there is a very stiff competition in the number of EDA company's products.

VLSI Course Syllabus

Typically in a VLSI Design course what is expected is to learn how to program an FPGA, Understand an indepth analysis of semiconductor technologies for back-end design. So in order to keep the students abreast of the latest many universities have their own syllabus but the major areas of focus in a VLSI Design course is
Basics of VLSI
Semiconductor Physics & modeling
Modelling of Digital Systems using HDL(Verilog or VHDL or System C)
VLSI SYSTEM DESIGN AND TESTING
ANALOG and Mixed Signal Design
COMPUTER AIDED DESIGN FOR VLSI
Modeling LAB using either Verilog or VHDL, Physical design layout tools etc.