EC 6601VLSI Question Bank

KARPAGA VINAYAGACOLLEGE OF ENGINEERING AND TECHNOLOGY DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING QUESTION BANK SUBJECT CODE: EC6601 YEAR/BRANCH: III / ECE

SUBJECT NAME: VLSI Design SEMESTER: VI

UNIT I MOS TRANSISTOR PRINCIPLE Part A 1. What are four generations of Integration Circuits? 2.What are the different layers in MOS transistors? 3.What is Enhancement mode transistor? 4.What is Depletion mode Device? 5.When the channel is said to be pinched –off? 6.Give the different types of CMOS process? 7.Draw the schematic diagram of the tristate inverter. (May/June 2009) 8. What is the fundamental goal in Device modeling? 9. Define Short Channel devices? 10.What is pull down and pull up device? 11.Why NMOS technology is preferred more than PMOS technology? 12.What are the different operating regions for an MOS transistor? 13.What are the different MOS layers? 14.What is Stick Diagram? 15.What are the uses of Stick diagram? 16.Give the various color coding used in stick diagram? 17.Define Threshold voltage in CMOS? 18.What is Body effect?(May/June 2009) 19.What is Channel-length modulation?(May/June 2009) 20.Give the basic inverter circuit. 21.Give the CMOS inverter DC transfer characteristics and operating region 22Define Rise time,Fall time,and Delay time.(Nov/Dec 2008) 23.State the differences between CMOS and Bipolar Technology(April/May 2008) 24.Define SSI, MSI, LSI and VLSI. (May/June 2009) 25.Give the exp. for Rise Time & Fall Time in CMOS Inverter Circuit. (April/May 2008) PART B

1.Draw a NMOS inverter, its stick diagram and MOS layout diagram.(April/May 2008) 2.Explain in detail the second order effects in MOSFET. 3.Explain in detail the switching characteristics of CMOS inverter.(Nov/Dec 2008) 4.Explain in detail the CMOS inverter DC Characteristics. 5.Explain in detail the MOS transistor theory. 6.Give the MOS Gate Capacitance Model. 7.Discuss Non-Ideal I-V Effects. 8.Explain CMOS Technologies.(May/June 2009) 9.Discuss the Layout Design Rules.(dec2008) 10.Explain with neat diagram the SOI process and mention its advantages. (Nov/Dec 2008) 11.Derive the Pull-Up to Pull-Down ratio for an nMOS inverter driven by another nMOS inverter. (April/May 2008) 12.Explain in detail the MOS transistor figure of merit. Obtain an expression for it. (April/May 08) 13. What is scaling ? Explain different types. 14.State the impacts of scaling on Design. 15.Write short notes on Device models in Spice UNIT II COMBINATIONAL LOGIC CIRCUITS Part A 1. What are two components of Power dissipation. 2. What is Latch – up? 3. Give the different levels at which the critical path gets affected. 4. Define logical effort 5. What is parasitic Delay-based 6. Define sizing and its advantages. 7. Define wire pitch and aspect ratio. 8. Draw capacitance model and give the diferent formulae for capacitances 9. Define electromigration and self heating 10.Define transistor scaling and the different parameters involved in it. 11.Write an expression for Power Dissipation in CMOS inverter. (Nov/Dec 2008) 12.What is bubble pushing. 13.2.What do you mean by pass transistor 14.Define SDFF. 15.Define TSPC 16.What is Synchronizer. 17.What is Arbiter. PART B

18.Explain parasitic delay in detail. 19.Explain different types of power dissipation in Cmos circiuts and how it can be reduced. 20.Interconnect increases circuit delay,discuss. 21.Explain the different realibility problems(hard errors) in detail. 22.With neat diagram of Latch-up effect in p-well structure explain Latch-up problem and the steps involved to overcome it. (April/May 2008) 23.What are Ratioed circuits explain different types in detail. 24.Explain different Dynamic circuits in detail. 25.Explain the design of latches and flip flops using transmission gate. 26.Write short notes on Time Borrowing. Draw timing diagram and explain. 27.Explain how communication is done between two asynchronous systems. UNIT III SEQUENTIAL LOGIC CIRCUITS Part A 1. What is synchronous sequential logic circuit? 2. What is bistability principle? 3. What is metastable? 4. List the timing parameters of reisters. 5. What is race condition? 6. Define global clock? 7. What is clock skew? 8. What is clock jitter? 9. Define pipelining. 10.What is sense amplifier? 11.Design one transistor D-RAM cell. (May-June 2015) 12.Differentiate latch and flip-flop. (Nov-Dec 2014) 13.What are synchronizers (May-June 2014/13) 14.Design a one bit dynamic register using pass transistor. (Nov-Dec 2013) 15.Mention the qualities of an ideal sequencing method. (Nov-Dec 2012) 16.What are the Factors That Cause Timing Failures? (May-June 2012) 17.What are the different memory control circuits? 18.Differentiate between S-RAM and D-RAM. 19.What are the different low power memory circuits? 20.What are the clocking strategies of Sequential circuit design? PART-B 1. a) Design a D-latch and D flip-flop using Transmission gate b) Design a one bit dynamic inverting and 2 bit non inverting register using pass transistor (May-June 2015/Nov-Dec 2013) 2. What are Klass semi dynamic flip flops? Explain with their logic circuits. (Nov-Dec 2014) 3. Explain the methodology of sequential circuit design of latches and flip-flops. (May-June 2014)

4. a) Draw and explain the operation of conventional CMOS, pulsed and resettable latches b) Write a brief note on sequential dynamic circuits. (Nov-Dec 2012) 5. Explain in detail about the pipelining concept used in sequential circuits. 6. Explain in detail about memory architectures and memory control circuits. 7. Timing issues and clock line strategies in sequential circuits. 8. Discuss in detail about low power memory circuits. UNIT IV DESIGNING ARITHMETIC BUILDING BLOCKS Part A 1. What is bit sliced datapath? 2. Define critical path? 3. Define inverter property. 4. List the disadvantages of monolithic lookahead adder. 5. What is an array multiplier? 6. What is Partial Product accumulation? 7. What are data path circuits? 8. What is speed-area trade off? 9. What are barrel shifters? 10.What are the different types of multipliers used in ALU’s? 11.What are the different types of dividers used in ALU’s? 12.What are high speed adders? Discuss the types. 13.What are accumulators? 14.What is ripple-carry adder? 15.What is carry look ahead adder? 16.Write down the equation for carry generate and carry propagate. 17.What are the two approaches to reduce delay in adders? 18.What are the two techniques to speed up the multiplication process? 19.What is modified Booth algorithm? Part B 1. Explain in detail about datapath circuits? 2. Explain about multipliers with necessary diagrams? 3. Explain about speed and tradeoff in arithmetic building blocks. 4. Draw the diagram of a carry look ahead adder and explain the principle. 5. Describe in detail Booth’s Multiplication algorithm and its hardware implementation. 6. Discuss about the different high speed adders. 7. Discuss in detail about dividers. 8. Explain briefly a) Barrel shifter b) Ripple carry adder

UNIT V IMPLEMENTATION STRATEGIES Part A 1. Differentiate between the standard cell based ASICs and full custom ASIC. 2. What are macros? 3. What is Programmable Interconnects? 4. Compare Antifuse, SRAM, EPROM and EEPROM technologies with respect to erasing mechanism. 5. What is meant by CBIC? 6. How granularity of logic block influences the performance of an FPGA? 7. What is meant by FPGA? 8. Draw the ACT1 logic module 9. What is the difference between Act2 and Act3 logic modules 10. Define the terms connectivity matrix, and PIP’s. 11. Distinguish between Altera 5000 and 7000. 12. Give the XILINX Configurable Logic Block. 13. Differentiate between Altera MAX 9000 and Altera FLEX interconnects architecture? 14. Compare between Xilinx LCA, Actel Act and Altera MAX architecture? 15. What are the advantages and disadvantages of FPGA compared to ASIC? 16. Define flexible blocks. 17. What is standard cell? 18. Define Manufacturing lead time.

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Part B Describe the salient features of Xilinx LCA interconnect architecture. Explain configurable logic block and Programmable routing matrix of Xilinx XC 4000 FPGA. How sequential circuit is implemented in Altera Flex 8000 FPGA. Explain the configurable logic block of Xilinx XC4000 FPGA. Explain the performance & characteristics for the following design styles. a) Standard cells. b) Cell based ASIC. a). What are the various methodologies of FPGA? Explain the same with neat diagram? b). Discuss the different types of I/O cells used in programmable ASIC’s Explain the ASIC design flow with a neat diagram and write the difference between custom IC and standard IC? Explain in detail about the FPGA building block architectures with neat diagrams. Explain about ASIC cell libraries in detail.