UNIT 2
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MKCE-ECE VLSI Design Unit-2 MOSFET TRANSISTOR 2 MARK QUESTIONS & ANSWERS: 1. What is MOSFET?(Apr/May 2011) Metal oxide semiconductor field effect transistor. A type of transistor that is controlled by voltage rather than current. 2. What is the fundamental goal in Device modeling? To obtain the functional relationship among the terminal electrical variables of the device that is to be modeled. 3. Define Short Channel devices? Transistors with Channel length less than 3- 5 microns are termed as Short channel devices. With short channel devices the ratio between the lateral & vertical dimensions are reduced. 4. What is pull down device? [Nov/Dec-2009] A device connected so as to pull the output voltage to the lower supply voltage usually 0V is called pull down device. 5. What is pull up device? A device connected so as to pull the output voltage to the upper supply voltage usually VDD is called pull up device. 6. Why NMOS technology is preferred more than PMOS technology?
description
two marks
Transcript of UNIT 2
M
MKCE-ECE
VLSI Design
Unit-2
MOSFET TRANSISTOR
2 MARK QUESTIONS & ANSWERS:
1. What is MOSFET?(Apr/May 2011)
Metal oxide semiconductor field effect transistor. A type of transistor that is controlled by voltage rather than current.
2. What is the fundamental goal in Device modeling?
To obtain the functional relationship among the terminal electrical variables of the device that is to be modeled.
3. Define Short Channel devices?
Transistors with Channel length less than 3- 5 microns are termed as Short channel devices. With short channel devices the ratio between the lateral & vertical dimensions are reduced.
4. What is pull down device? [Nov/Dec-2009]
A device connected so as to pull the output voltage to the lower supply voltage usually 0V is called pull down device.
5. What is pull up device?
A device connected so as to pull the output voltage to the upper supply voltage usually VDD is called pull up device.
6. Why NMOS technology is preferred more than PMOS technology?
N- Channel transistors has greater switching speed when compared tp PMOS transistors.
7. What are the different operating regions for an MOS transistor?
a. Cutoff region
b. Non- Saturated Region
c. Saturated Region
8. What are the different MOS layers?
a. n-diffusion
b. p-diffusion
c. Polysilicon
d. Metal
9. What are the different operating regions for an NMOS transistor?
a. Accumulation Mode.
b. Depletion Mode
c. Inversion Mode
10. Compare between CMOS and bipolar technologies. (Nov 2007)
CMOS Technology Bipolar technology
Low static power dissipation
High input impedance (low drive current)
Scalable threshold voltage
High noise margin
High packing density
High delay sensitivity to load (fan-out limitations)
Low output drive current
Low gm (gm Vin)
11. Define Threshold voltage in CMOS. (Dec 2006)
The Threshold voltage, VT for a MOS transistor can be defined as the voltage applied between the gate and the source of the MOS transistor below which the drain to source current, IDS effectively drops to zero.
12. Define the mos equation
Ids= { 0 Vgs
