B.TECH - Semester 6 vlsi design Question Paper 2020 (feb)
Practice authentic previous year university questions for better exam preparation.
Sample Questions
- For the fabrication of MOSFET, it is needed to grow gate oxide and field (isolation) oxide. Which oxidation mechanism will you choose for each? Why?
- Why annealing is needed after ion implantation process?
- State the laws governing diffusion process.
- Plot the output characteristics of n-channel MOSFET and label the regions of operations.
- Draw the stick diagram of a CMOS inverter.
- Define subthreshold slope of a MOSFET.
- What are the advantages and limitations of pass transistor logic circuits?
- Distinguish between static and dynamic power dissipation in VLSI.
- What is sense amplifier? Why they are used in memory circuits?
- Sketch a dot diagram for a 3 -input XOR using a PLA. $$ \text { ( } 10 \times 2=20 \text { Marks) } $$ Answer any one full questions from each module.
- (a) Explain Czhochralski and Float zone techniques for crystal growth and compare them.
- (b) What is meant by infinite source diffusion and limited source diffusion? Plot the doping profile in each case and explain them with the help of relevant equations.
- (a) Plot the doping profile after an ion implantation and explain the profile with the help of necessary equations.
- (b) With the help of neat diagrams explain the steps involved in photolithographic process.
- (c) With neat diagrams explain the steps involved in the fabrication of CMOS using $n$-well technology.
- (a) Draw a flow chart of VLSI design flow and explain.
- (b) What is meant by scaling in MOSFETs? Which are the different scaling models?
- (c) Compare the effects of constant field scaling and general scaling on various device parameters.
- (a) Which are the capacitances present in MOSFET structure? Explain.
- (b) Explain the short channel effects in MOSFETs. 8
- (c) Explain $\lambda$ based design rules.
- (a) Draw the circuit of a CMOS inverter. Plot its voltage transfer characteristics (VTC) and derive an expression for switching threshold. How does the relative sizes of the devices affects the VTC. 10
- (b) Explain the working a 16-bit carry-by pass adder and write down the expression for worst case delay. OR
- (a) Explain the various types of power dissipation in CMOS inverter? Derive the expression for total power consumption of a CMOS inverter.
- (b) Implement a 16 bit adder using linear carry select and square root carry select techniques and compare the delay. Module - IV
- (a) Design a master slave D flip flop using multiplexers and implement the design using transmission gates.
- (b) Explain the read and write operation of a three-transistor DRAM cell. OR
- (a) Draw a NOR based ROM array to store four, 4bit data. Explain write and read operations.
- (b) What is meant by fault models? Which are the different fault models used? Explain.
- (c) What is FPGA? Explain its architecture.