Transcript L-EDIT Tutorial - Scott Thompson

L-EDIT Tutorial
EEL 4310
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Why use L-edit?
• L-Edit is a freeware and is very useful for
academic purposes
• Though industry uses Cadence, L-Edit can
illustrative the significant points for laying
out CMOS circuits. Cadence is rather
complex in comparison.
• L-Edit can be used to extract parasitic
capacitance which enables us to predict
the delay in CMOS circuits.
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DOWNLOAD INSTRUCTIONS
• The downloadable version of L-edit can be
found in Dr Thompson’s website.
http://www.thompson.ece.ufl.edu/Fall2007/
downloads.htm
• Download the file from the first linkstu712.zip:
Ftp site for L-Edit Pro student version
• You can also download L-Edit from
www.tanner.com/eda
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Setup
• This version must run in 256 colors.
• For Windows XP users, set the display by
right clicking the short cut created for Ledit and choosing properties.
• Then click the compatibility tab. Under
display settings click 256 colors.
• Open L-edit
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Drawing Layout
• Create new Layout file
– File > New.
– In the following open window, Browse and choose
‘mamin08.tdb’ in ‘Copy TDB setup from file’ area. It
usually locates in ~\stu712\mosis\. Else browse to
find mamin08.tdb located in the mosis folder of stu712
file
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Relationship between
Lambda and Microns
• Setup > Design
Establishing
l=.5m, therefore
2l=1m
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To establish GRID
• Zoom the window to see grid
• Distance between grid points is 1 lambda
• In order to set mouse snap to Grid :
– Click Setup -> Design
– Click on the Grid tab
– Set Mouse snap grid to 1 locator unit
Now the technology is setup!
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Inverter Layout
• Layout Specifications:
NMOS:
– L = 2 Lambda, W = 6 Lambda
PMOS:
– L = 2 Lambda, W = 12 Lambda
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PMOS
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Choose N-Well in the left palette
and draw a box.
In the N-Well area, draw PSelect. Notice that the size and
position should obey Design
Rule, which can be found at
http://www.mosis.org/Technical/
Layermaps/lmscmos_scnpc.html.
With the help of DRC button ,
the violation of design rule can
be shown by right clicking the
place which is highlighted. It is a
good idea to run DRC at each
stage of your design so that you
can fix any error along the way
Draw Active.
Draw Poly.
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NMOS
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Do not need to draw
P-Well because the
empty grid of L-Edit
stands for P-Well.
Draw N-Select.
Draw Active.
Draw Poly.
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Power Lines
• Draw Vdd and Gnd Lines
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Well Taps
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For PMOS, place a small
N-Select on the N-Well,
add a small Active layer.
From this active layer put
contacts to the Metal1
layer that connects to
VDD.
For NMOS, on the P-Well
substrate, place a small
P-Select and then Active
layer. From this active
layer put contacts to the
Metal1 layer that
connects to GND.
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Connect Poly of PMOS
and NMOS.
Connect source of PMOS
to VDD by Metal1.
Connect source of NMOS
to GND by Metal 1.
Connect Drain of PMOS
and NMOS by Metal 1.
Add an input connect
between Metal1 and Poly.
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LABELS
• Label the INPUT, OUTPUT, VDD and GND using
button
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Design Rule Check
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Click Tools -> DRC (or the DRC box in
the toolbar)
Run DRC for the total layout.
Click the Write errors to file box, and give
a descriptive filename
Fix the errors listed.
Once there is no DRC error shown, the
layout is ready to be extracted.
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Submitting HW
• When submitting an L-edit file as part of a
homework or project, mail it to
[email protected]
• I only need the *.tdb file
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