NARAYANA ENGINEERING COLLEGE::NELLORE/GUDUR DEPARTMENT OF ECE

ACADEMIC YEAR: 2012 2013 OBECTIVE QUESTIONS Subject: VLSI Design (R 09) ,Common to ECE &EIE Class : I11B.TECH. II SEM Faculty : K.Murali/ B. Gopichandra kumar/ R.Gunasekhar

UNIT - 1
Multiple choice 1. The speed power product of any MOS technology is measured in [ C ] a)KJ b) MW-sec c) PJ d) Joules 2. For depletion mode MOSFET, threshold voltage [ D ] a) 0.2 V DD b) -0.2 V DD c) 0.8 V DD d) -0.8 V DD 3. The technology which is characterized by high speed [ D ] a)CMOS b) BICMOS c) GaAs d)ECL 4. Latch up in CMOS device can be avoided by [ B ] A) Increasing temp b) doping control c) increasing the substrate resistance d)decreasing substrate doping level 5. Material used for metallization is [ A ] a)Aluminum b) copper c)silver d)tungsten 6. Material used for gate oxide in MOS technology. [ C ] a) Si b) Ge c) Sio2 d) AlO2 7. Poly silicon is a _________ material [ C ] a) Crystalline b) Amorphous c) Poly crystalline d) None 8. Silicide is combination of [ A ] a) Metal poly b) Metal-Silicon c) Metal-Ge d) Metal-SiO2 9. In modern CMOS fabrication, the pattern on each layer is created by a) Ion implantation b) Oxidation c) Photo lithography d) Encapsulation 10. The advantage of twin- tub process [ C ] a) Low complexity b) Low cost depletion c) Latch up immunity d) high mask count Fill in the blanks: 11. Expansion of CVD is ___chemical vapour deposition___________ 12.______Electron_______________ lithography is preferred in submicron device dimension 13. The kinetics of thermal oxidation is modeled by ___deal and groover___________________model. 14. The static power dissipation in CMOS technology is _____zero__________ 15. In normal mode of operation in CMOS, substrate terminal of NMOS is connected to ____vss_______ and substrate terminal of PMOS is connected to ___vdd________ 16. CMOS technology is high delay than ____bipolar_______________ Technology 17. The deficiency of MOS technology is ___limited load driving capacity_____________________ 18. Under DEPLETION mode NMOS is ____ON____________state. 19. NMOS FETs are ___faster_________than PMOS FETs 20. Power dissipation in NMOS technology is ____high_______compared to CMOS technology.

UNIT - 2
Multiple choice 1. MOSFET operated in saturation when [ C ] (a) Vds = vgs-vt (b) vds < vgs-vt (c) Vds > vgs-vt (d) Vds < vt 2. For faster NMOS circuits, one would choose the following type of substrate [ B ] (a) 110 Oriented n - type substrate (c) 111 Oriented p - type substrate (b) 100 oriented p - type substrate (d) 111 oriented n- type substrate 3. Pull up to pull down ratio for n MOS inverter driven by another n MOS inverter is [ D ] (a) 4:4 (b) 4:1 (c) 1:4 (d) 8:1

4. The following device is less likely to suffer latch up [ C ] (a)n MOS (b) CMOS (c) BICMOS (d) PMOS 5. In CMOS inverter if n=p & if Vtn =Vtp, then the logic levels are disposed about at a point where [ C ] (a)VIN = Vout = 0.1 VIN (b VIN = 0.5 VDD (c) VIN = Vout =0.5 VDD (d) VIN = Vout = VDD 6. The figure of merit of MOS transistor can be expressed as [ C ] a) g m Cg b)

cg gm

c)

gm cg

d) [ D ] c) 1250 cm2/V.sec

2
d) 480 cm2/V.sec

7. Typical mobility of holes (Bulk) is a) 650cm2/V.sec b) 240 cm2/V.sec

8. Pickup the true statement with respect to Bi-CMOS Inverter [ C ] a) Low input impedance b) High output impedance c) high noise margin d) Low driving capability 9. To achieve best performance NMOS inverter transfer characteristics, Zpu/Zpd ratio should be a) Zero b) One c) As low as possible d) As high as possible [ C ] 10. Number of transistors to implement three-input AND gate using pass transistor logic is a) 6 b) 3 c) 5 d) 9 [B ] Fill in the blanks: 11. An inverter driven through one or more pass transistor should have Zpu/Zpd ratio of_ _____8 : 1_______ 12. The threshold voltage is increased due to ___body effect_________________ 13. More lightly doped substrate ___________less___________ will be the body effect 14. The drain- source current (IDS) for NMOS under saturation can be expressed as___________ 15. Transconductance of MOS transistor (gm) is expressed as__________ 16. For devices of similar dimension n-channel is ___faster________ than the p channel 17. A simple BICMOS inverter has ___high____input impedance and__low____ output impedance 18. The power dissipation is ___low______in CMOS technology. 19. Bi-CMOS inverter has high driving capability than ___cmos____technology . 20. For high performance CMOS inverter

n p

should be__low______

UNIT 3
Multiple choices 1. The color encoding for polysilicon is [ A (a) Red (b) Green (c) Blue (d) Orange 2. The color encoding of VIA in double metal CMOS p-well process [ B a) Red b) Black c) Brown d) Yellow 3. Metal 1 to metal 1 spacing in layout design is [ C (a) 4 (b) 2 (c) 3 ( d) 1 4. The buried contact is made between [ B (a) Poly to metal (b) poly to diff (c) poly to diff using metal (d) Metal to metal 5.In NMOS layout design style, the colour of contact cut [ A ] a) Black b) Green c) Blue d) Red ] ] ] ]

6. What is color of metal 1 (CMOS encoding) [ B a) Black b) Blue c) Red d) Yellow 7. The p-type transistors are placed above the [ C a) Poly silicon b) diffusion c) Demarcation line d) metal 8. The minimum gap between diffusion and diffusion is [ A a) 2 b) 5 c) 7 d) 10 9. The size of a transistor is usually designed in terms of [ D a) Drain b) source c) metal d) channel length 10. According to 2m CMOS technology, the minimum separation between contact cuts a) 2 m b) 4 m c) 6 m d) 5 m [ B

] ] ] ] ]

Fill in the blanks 11. The layer preferred for global distribution of power buses is __METAL 2________________ 12._____STICK DIAGRAM___________________ is used to convey layer information. 13. For CMOS circuits stick encodings for demarcation line is ___BROWN________________in color. 14. The power and ground lines often called _______POWER RANGE__________ 15. The minimum width of metal 1 layer is _________3 _____________ 16. A __MOS TRANSISTOR_________is formed wherever polysilicon crosses Diffusion 17. Metal 1 for_____LOCAL DISTRIBUTION_______ and metal 2 for __GLOBAL DISTRIBUTION_______of power lines in stick notation 18. The minimum polysilicon width is______2 __________19. As fabrication technology improves, the heat sink size___REDUCES__________ 20. In CMOS design style, Demarcation line is shown by__DOTTED LINE__________

UNIT 4
Multiple choice 1. Power dissipation per unit area is scaled by (a) (b) (c) (d) [ A] d) 0.1x10 2 pF/m2 [ C ] 2. Typical value of Diffusion capacitor(C area ) in 5 m technology a) 1.0x10 4 pF/m2 b) 1.0X10 2 pF/m2= c) 0.1x10 4 pF/m2 3. The rise time of CMOS inverters is a) = (b) = (c) = b) = [ C ]

4. The typical value of load capacitance is [ D ] a) CL < 10 4 cg (b) CL 10 4 cg (c) CL = 10 14 cg (d) CL 10 14 cg 5. The characteristics of a metal layer are [A ] a) Low R; low C b) low R; moderate C c) Low R; moderate C d) moderate R; high C 6. The typical sheet resistance of polysilicon for 5m is [ D ] a) 0-10 b) 10-14 c) 120 to 140 d) 15 to 100 7. The overall delay Td for n sections is given by [ B ] a) Td= nrc ( ) b) Td= n2 rc( ) c) Td = n2r2 c( ) d) Td= n r2 c( ) 8. Deposition of the metal/silicon alloy prior to sintering may be done with [ A ] a) Sputtering b) diffusion c) Implantation d) Metallization 9. What is the formula for Rise-time estimation [ A ]

a) Tr=

3C

p V DD

b) Tr =

3C v
p

c) Tr =

3C

DD

p V DD 2

d) Tr =

C V DD
L p

10. The formula for fall-time estimation in CMOS inverter is 2 2 3C 3C L L 3 C L a) Tf = b) Tf = c) Tf = p v DD p V DD n V DD

[ C d)

3C V DD 2
L n

Fill in the blanks 11. The propagation delay of n sections is given by ________________________________ 12. The layer in which metal is deposited on poly silicon is called _____SILICIDE________________ 13. The sheet resistance of pdiff is _____2 : 5_________ times that of n-diffusion. 14. The values for N-diffusion region are___0.4_______ times the P-diffusion regions. 15. Bi-CMOS technology is reasonably good for__HIGH LOW DRIVING CAPABILITY____________ 16. Power consumption in CMOS circuits depends on __FREQUENCY_____________at which they operate. 17. ___METAL 1_____ layer is suitable for routing Vdd or Vss 18. The ___LARGE CAPACITIVE__________________load cant be driven by a single inverter. 19. In Bi-Polar transistor collector current depends ____EXPONENTIALY____________on Vbe. 20. The Delay for Bi-CMOS inverter is _______REDUCED____________by a factor of h f e compared with a CMOS Inverter.