The George Washington University School of Engineering and Applied Science Department of Electrical and Computer Engineering

1
The George Washington UniversitySchool of
Engineering and Applied ScienceDepartment of
Electrical and Computer Engineering

• ECE122 Lab 7
• MOSFET Parameters and Scaling Effects

Jason Woytowich October 14, 2005
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CMOS Scaling

• Devices are constantly shrinking in an effort to
  increase the number of devices on a chip.
• The state-of-the-art mass production is moving
  into 65nm.
• Clock speeds are scaled up to increase
  performance.

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Effects on the Device

• Short-channel effects on VT
• Velocity saturation
• Gate leakage current (IG)
• Subthreshold current (ID)

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Effects on the Circuit

• Increased power consumption. Leads to decreased
  supply voltage and smaller noise margins.
• Increased role of wiring resistance, inductance
  and capacitance.
• Interconnect coupling
• IR Drop
• Electromigration

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Spice MODELS

• The standard spice model is not sufficient to
  capture all of these effects.
• There have been many upgrades to it in order to
  increase its effectiveness.

Level 1 5 Parameters
Level 49 100 Parameters
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Review of Spice Parameters
Page 132 in Textbook
.model nmos nmos Level1 Vto1.0 Kp3.0E-5
Gamma0.35 Phi0.65 Lambda0.02 Tox0.
1u Nsub1.0E15 Nss1.0E10 Ld0.01u
Tpg1.00 Uo700.0 Af1.2 Kf1.0E-26 Is1.0E
-15 Js1.0E-8 Pb0.75 Cj2.0E-4 Mj0.5
Cjsw1.00E-9 Mjsw0.33 Fc0.5
Cgbo2.0E-10 Cgdo4.00E-11 Cgso4.00E-11
Rd10.0 Rs10.0 Rsh30.0
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Your task

• Attempt to use a Level 1 Spice model to model a
  real transistors IV characteristic.
• Measure the mean-square error.
• Error 1/N SUM((IREAL-IMODEL)2)
• Bonus to the least error.

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The REAL Data

• The IBM_018u.md file located under homework 5 on
  the website will serve as the real data.

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The test setup
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The simulation

• A DC sweep of 100 points of VDS from 0 to 1.8V
• A Secondary sweep of 10 points of VGS from 0 to
  1.8V

.dc source VDS lin 100 0 1.8 sweep source VGS lin
10 0 1.8 .include "C\Documents and
Settings\Student\Desktop\ECE122_Lab7\ml1_typ.md"
.include "C\Documents and Settings\Student\Deskto
p\ECE122_Lab7\IBM_018u.md" .print dc i(M1,D)
Main circuit MosfetTest M1 D G Gnd Gnd NMOS
L180n W1u AD66p PD24u AS66p PS24u VGS G
Gnd 5.0 VDS D Gnd 5.0 End of main circuit
MosfetTest
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Example
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What we want to see.

• The two graphs superimposed on each other.
• The method/reasoning for your changes to the
  model file.
• Any code you use to calculate the error.
• The model file.