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Monster Media 1996 #15
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Monster Media Number 15 (Monster Media)(July 1996).ISO
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TUTOR.LHI
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Starting the Tutorial
Starting the Tutotial
The layout of a small IC is used to familiarize a new user with LASI. The
circuit is a simple bipolar opamp, but not necessarily a good one. It is
mainly designed to show drawing techniques.
When you installed the drawing files from a ZIP file, you create a
subdirectory on your hard disk called \LASI5\TUTOR. This is the drawing
directory for the tutorial IC.
The tutorial files contain a small batch file (TUTOR.BAT) that
reconstructs the drawing and then runs the main LASI drawing program.
The batch uses the TLCIN.EXE program which converts the drawing from
"TLC" files, which are ASCII sequential files, into "BP5" and "CL5"
files, which are faster binary files that LASI actually uses in the
drawing. The batch then runs LASI and puts you immediately into what is
called "Cell Mode" with the drawing of a small IC. The drawing is a
"cell" named OPAMP.
When in the drawing, test out the LASI main help system by pressing F1.
This calls the help program LHI.EXE with the main LASI help text file.
LHI is an information reader that can be called at any time while running
LASI to explain any procedures or commands. Exit LHI by clicking "Back",
"Quit" or by pressing ESC. You may also place the mouse cursor on a
command button and press F1. This calls help for that command directly.
When in the main help system, read a few of the topics. If you are new to
LASI, don't expect to learn the details immediately. There are many
subtleties in LASI.
Return to this tutorial any time by pressing F2 when a drawing is
displayed. The tutorial drawing is arranged so that pressing F2 calls the
command: "DOS, \LASI5\LHI \LASI5\TUTOR\TUTOR.HLP", which starts LHI again
from a drawing context with the tutorial text file. Note that "\LASI5" is
added as a path because the DOS PATH may not contain "\LASI5" just yet.
In fact, typing the command: "\LASI5\LHI \LASI5\TUTOR\TUTOR.HLP" will run
this tutorial from DOS in any directory on the hard disk where LASI is
installed. Read the topic "Help on Help" under General Information in the
main LASI help text for more information on LHI command line arguments.
If you want to start the tutorial drawing from DOS without reinstalling
the drawing, do the following:
1. Be sure that the DOS PATH contains the term "disk:\LASI5", where
"disk" is the name of the hard drive where you installed LASI.
2. Make the \LASI5\TUTOR directory the default directory.
3. If you want to reconstruct completely, run the TUTOR.BAT batch file
again by typing "tutor".
4. If the drawing is OK and you want to run LASI immediately, just type
"lasi" or "lasi" followed by the name of a cell, such as "npn1" to go
directly to Cell Mode, as the batch file does.
5. When in a cell drawing (Cell Mode), press F2 for this tutorial.
Basic Transistor Cells
Introduction
The opamp is made from bipolar transistors based on a simple bipolar IC
process. There are only 8 masking layers used, which are in the usual
terminology:
1 N-type Buried Island
2 P-type Isolation
3 N-type Sinker
4 P-type Base
5 P-type Resistor
6 N-type Emitter
7 Contact
8 Metallization
The schematic is on layer 32.
Layers 60-63 contain text that is to be used by the LASICKT.EXE program
which constructs SPICE code from the layout and schematic. To learn more
about this type "LHI \LASI5\LASICKT.HLP" at the DOS command line, or run
LASICKT and press F1.
There are different types of NPN and PNP transistors, some resistors and
miscellaneous bits and pieces. These are all made as rank 1 cells.
Going to a Cell
1. If you are not there already, enter Cell Mode with the NPN1 transistor
by clicking your LEFT mouse button on the LIST command and then click
the LEFT mouse button on the name "NPN1" in the listing. The cell
should appear.
The cell is made from "basic objects": boxes, polygons and text.
If the transistor does not show completely in the display window click
the FIT command button with the LEFT mouse button.
2. Use the commands ZOOM, XPND and the pan arrows to examine the cell
more closely.
3. There are two menus of commands that can be flipped by clicking the
RIGHT mouse button. The commands are always selected by clicking the
LEFT mouse button on a menu button. The menu button "pushes" as you
run the cursor over it, and clicking the mouse activates it. The LEFT
mouse button is always used to make cursor points or windows to input
graphical information. Flip the menus to see the different commands,
and if you are curious, place the mouse cursor on a button and press
F1. You should jump to the help information for that command.
The Grid Systems
When you work with LASI you will discover that your mouse cursor jumps
between two grid systems: the unit grid and the working grid. This may
seem confusing, but its purpose is to control the placement of drawing
objects to certain discrete positions. As we know, IC layouts are not
really drawings, but are precisely placed items.
You use the SET command to program working grid sizes, and then click the
WGRD command to step through them. The number and size is up to you. This
tutorial is set up for 3 convenient sizes of 1um, 5um and 25um. The
working grid is indicated at the bottom of the display.
The DGRD and GRID commands control a grid of white dots on the screen.
DGRD steps through a set of dot spacings, and GRID turns the dots on and
off. The dot grid spacings are also programmed by the SET command. The
dot grid is a drawing aid and has no control over object placement.
Hint: Pressing the A or ALT keys flips the mouse cursor between working
and unit grids.
The Layer Table
The tutorial has been setup to use a new feature of LASI 5, a Layer
Table. The table is a list of layers by names and numbers (set in the
FORM.DBD file). With certain commands, the table appears as a vertical
row of buttons that replaces the command menu. When the table appears,
click the buttons with the LEFT mouse button, and then click the LEFT
mouse button OFF the menu or press ESC when you are finished.
LASI 5 also works with layer numbers, just as did previous versions of
LASI. To toggle between the layer table and numbered layers, press
CTRL-ENTER.
Getting Objects
1. You will find that the transistor is mostly drawn with box objects.
First use the GET and FGET commands by making a cursor window that
crosses a box side. Notice that the command and the points are
indicated at the bottom of the screen and that the cursor turns into a
dotted rectangle. When you use GET, a side of the box turns bright
white. This is called "active". Using FGET (full get) makes the entire
box object active.
2. Click the INFO or SHOW commands if you want information on an object.
SHOW is like INFO except that it gives more information on a new
screen. To exit a SHOW screen press ESC.
3. The base of the transistor is made from a poly(gon) object. To "get" a
poly object think of it as a series of vertices and make a cursor
rectangle around one or more vertices. A diamond symbol will appear at
an active vertex, and a segment line will turn bright white if
adjacent vertices are active. GET makes a single vertex active. FGET
makes an entire poly or path active. Use the INFO and SHOW commands
again on the poly.
4. Try the PUT and FPUT commands. The "put" commands are the inverse of
any "get" commands.
Hint: You can start a command over again by reclicking the command or by
pressing ESC.
Moving Objects
1. Now try the MOV command. First make one or more box sides active with
GET and then click the MOV command. Notice that the mouse cursor now
jumps in discrete working grid distances and requires two input
points. Notice also that the cursor turns into a dotted vector to
indicate the movement.
2. Click the APUT (all put) command to make boxes inactive again.
3. Make a vertex active on the base poly. Try MOV again and notice that
vertices move discretely in any direction.
4. Click APUT again to make all objects inactive.
Adding Objects
1. You can now try the ADD command. To do so, first set the type of
object using the OBJ command. You only have a choice of "b" (box) or
"p" (path) in this case. (Later cellnames will be OK.) Make your
boxes by clicking at diagonally opposite corners. The boxes will be on
the layer indicated at the bottom of the screen. Notice that boxes
will be "snapped" into the working grid indicated at the bottom of the
screen.
2. Use the LAYR and CLYR command to set and change the layer of boxes.
These commans call the Layer Table if it is turned on. For CLYR to
work a box must have all four sides active.
You can use boxes for parts of a transistor (isolation, contacts etc.)
that would normally be rectangular.
3. Make polys by setting the object to "p" and clicking the cursor at
different points to add vertices. You will produce a sequence of line
segments with the last vertex active and marked by an "x". By adding
the last vertex at the same point as the first vertex, you produce a
closed polygon. Notice like boxes that the vertices are set at working
grid points.
4. Try the WDTH and CWSZ commands to set and change a poly's width.
Setting width greater than zero makes a poly into a "path".
In general, the term "path" refers to both poly and paths; a poly just
has zero width.
5. There are special commands ARC, VSTP, PREV, PBEG, PEND, VSTP, CUT and
JOIN that act on paths only. You can try these if you wish after you
have determined their function by consulting LHI (Put the cursor on
the command and press F1).
You would use closed polygons to make non-rectangular areas in a
transistor. (In this case, a base area with clipped corners, or PNP
emitters and collectors as you will find in the PNP1 cell)
6. Now add some text. Choose the TEXT command and click a reference
point, and then type in some characters terminated by ENTER. Flip the
menu and notice that the LAYR and WDTH commands are replaced by the
TLYR and TSIZ commands. Text is a form of path, and the TLYR, CLYR,
TSIZ and CWSZ work on it. Size for text is the same as character
height. Text is like a one vertex path, you "get" text by its
reference point, which is always in the lower left corner of the
character string. You can toggle this reference point on and off with
the T key.
More Commands
1. You should try the CPY, ROT and FLP commands on the boxes, paths and
text that you have made. These commands save time when symmetries
occur in a drawing.
CPY will copy individual active vertices, so you can copy pieces of
paths. Boxes copy only if they have all sides active.
ROT will rotate boxes paths and text. Boxes and text rotate in 90 deg
increments. Paths rotate to any angle.
FLP flips boxes, paths and text around a horizontal or vertical axis.
2. You can also try the WMOV and QMOV commands. These are composite
commands that combine the actions of "getting" and "moving". The
action of these commands on boxes, paths and text is the same except
that the WMOV command requires that the cursor window completely
enclose a box side. (WMOV also acts on whole cells as you will see
later.)
3. There are two commands, VIEW and OPEN that restrict the layers which
are shown on the display and limit the action of commands on different
layers. These commands call the Layer Table or accept a series of
individual layer numbers. Layers that are not VIEWed are never OPENed.
4. There are additional commands like AGET, WGET, STEP, SMSH, PSIZ and
OVSZ that act on basic objects. These are more rarely used and you
will find their purpose once you have worked with LASI for a while.
Cleaning Up
1. You should use the DEL command to delete all of the boxes that you
have added yourself. To delete a box you must have all sides active.
Remember that the FGET command "gets" all four sides.
2. Delete all the paths that you have added. When deleting paths you may
delete vertices individually if they are active, or a complete path if
all vertices are active. Remember, FGET will make all vertices of a
path active if a single vertex is made active.
3. Delete any text that you may have added by first making it active.
Hint 1: If you have made a mess of the transistor while trying commands,
instead of trying to delete and repair, use the UNDO command. This will
restore the original version of the cell.
Hint 2: If you have made a complete disaster of the cell, go back to DOS
and run TUTOR.BAT and replace the cell files completely.
The above hints are not to be taken as cynical. They demonstrate that
LASI has backups in case you do make errors.
To exit LASI from Cell Mode, first click SYS and then click QUIT.
More Cells
Use the LIST command to go to some of the other cells and see how they
are made. Remember that the cells are intended to demonstrate drawing,
not necessarily good device design.
The Main Cell Layout
Going to the Main Cell
1. Click the LIST command and choose OPAMP with the LEFT mouse button.
The overall IC layout should appear. Notice that it is rank 2 and is
made from the rank 1 cells along with boxes, paths and text. The
transistors are set in convenient locations and are interconnected
using paths on the metallization layer.
This is basically the way that you would layout an IC, although the
techniques vary with the individual.
2. Use the FIT, ZOOM, XPND and direction commands to examine the layout.
The opamp layout is a very simple example. More elaborate ICs may be
constructed by using subsections (like our opamp), and then assembling
these subsections into higher rank cells - and so on. This is how LASI
can handle large if not huge ICs.
Cell Commands
1. Try some of the commands that act on cells only. Select the CGET
command and rapidly double click the LEFT mouse button on a single
transistor cell. The cell should redraw in bright white. This is now
an active cell.
2. Use the MOV, ROT and FLP commands on the cell. Cells rotate in 90 deg
increments.
3. Make the cell inactive again by clicking the APUT button.
4. Try the OUTL command by rapidly double clicking the mouse on a cell.
The cell should be replaced by an outline. Now try the FULL command on
the cell by making a cursor window completely around the cell.
Outlining allows you to draw cells as a simple rectangle outline only.
Putting cells in outline can greatly improve drawing speed if you have
a large complex layout and a slow computer.
5. Also try the CMOV command which moves cells directly. Rapidly double
click on the cell and then click two points to move the cell. This too
is a time saver.
6. There are commands that work on both cells, boxes, paths and text such
as AGET, WGET and WMOV. These do more things at a time, but are also
more difficult to use. Try these commands. You will find that they are
useful for operations like moving a whole section of a drawing.
Hint: By quickly double clicking the LEFT mouse button while making a
cursor window in cell commands, you change the sense of the "get". The
commands then act on cells if there is any overlap of the cell in the
cursor window at all. If you wait a moment between clicks, the "get"
window must completely surround a cell.
Adding Cells
Now you can add a cell. To do so:
1. Click the OBJ command button and make the object the name of a cell
such as NPN1.
2. Select ADD and click the LEFT mouse button in some open location to
give a reference point. Your cell should appear and you can work with
it just like any other cell.
Note that the reference point is the 0,0 point in the added cell.
Deleting Cells
When you want to eliminate a cell, simply make the cell active and click
DEL to remove it. Once a cell is gone, it is gone, but cells are easy to
put back.
As with lesser objects, you can also use UNDO to restore the original
drawing, or reload it completely from TLC form.
The Schematic
The Schematic
There is a schematic diagram named $OPAMP independently living with the
IC layout. It is similar to the IC layout except that the cells are
symbols that are drawn and interconnected using zero width paths or open
polygons, whichever way you may want to think of them. Different layers
are used for the schematic and the layout, so that there will be no
conflict with the layer attributes of color, dashing and filling.
Notice also that in this example schematic cellnames have "$" as their
first character so you can easily tell a symbol from a device.
There are in effect two main cells, one for the IC, and one for the
schematic. There actually can be as many different cells on a rank as
memory capacity will allow.
You may want to use the schematic as a practice for working with open
polygons. You will find that the techniques are slightly different from
working with the IC layout.
System Mode
System Mode
You do actual drawing in Cell Mode, but you go through System Mode when
entering and exiting LASI. The commands in System Mode manipulate cells
as complete entities and perform various organizational tasks.
Put your mouse cursor on the command name and press F1 to find out what
the commands do.
You can try various commands. Their function is pretty straight forward
and generally requires little explanation. You should be warned however
that you can completely change some of the fundamental parameters, such
as scale or cellnames.
Once you work with LASI for a while this is not so scary.
Summary
Summary
You have been introduced to working with LASI. There are many more things
that you can do using the many commands, and many subtleties in the way
that the commands work that you will only learn by experience. When help
is needed press F1. You will soon learn that LASI is really pretty simple
in the way that it operates.
Always exit LASI by going to System Mode, first clicking SYS if you are
in Cell Mode, and then clicking QUIT. This stores the current cell on the
hard disk, and updates the drawing basic data files.