VLSI Design - December 2014

MU Electronics Engineering (Semester 7)

Total marks: --
Total time: -- INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary 1 (a) Draw a energy band diagram of MOS capacitor under external bias. 5 marks

1 (b) Compare buried and butting contact. 5 marks

1 (c) Implement following function using CMOS. $$F=\overline{a.b+c.d+e}$$<script type="math/tex; mode=display" id="MathJax-Element-1"> F=\overline{a.b+c.d+e} </script> 5 marks

1 (d) Draw the stick diagram for CMOS NOR gate. 5 marks

2 (a) Explain the various parameter affecting the threshold voltage of MOSFET. Explain the effect of ion implementation on threshold voltage of MOSFET. 5 marks

2 (b) Explain the complete fabrication process steps for CMOS Inverter using n-well process with the help of cross sectional diagram with all masking steps. 5 marks

3 (a) A CMOS symmetric inverter has following parameter
V_DD=-3.3V, V_m=0.6V, V_tp=-0.7v.
k_n=200 ?A/V² k_p=80 ?A/V²
Calculate noise margin of the circuit. 5 marks

3 (b) Define scaling-Discuss the advantages and disadvantages of different types of scaling. 5 marks

4 (a) Draw circuit diagram, stick diagram and layout for two input NOR gate using CMOS design rules. 5 marks

4 (b) Explain the operation of CMOS inverter with clearly mentioning the five cases given below.
i) V_in<v<sub>tn
ii) V_in=V_IL
iii) V_in=V_IH
iv) V_in>V_DD+V_tp
v) V_in=V_TH (Inverter threshold).</v<sub> 5 marks

5 (a) Write a verilog code for 4 bit ripple counter using D-FF as a basic component. 5 marks

5 (b) Compare passive load, active load NMOS inverter circuit with advantages and disadvantages. 5 marks

6 (a) Implement following Boolean function using CMOS logic $$y=\overline{x.y.z+x.w.y}$$<script type="math/tex; mode=display" id="MathJax-Element-2"> y=\overline{ x.y.z+x.w.y } </script> Draw stick diagram and layout of the circuit. 5 marks

6 (b) What is latch up in CMOS inverter and how to avoid it. 5 marks

Write short notes on any three:

7 (b) Y-chart for design flow. 5 marks

7 (c) Design rules and their necessity. 5 marks

7 (d) Oxidation. 5 marks