PC Electronics for your PC/pcelectronics.bin/_archive/LASI515B.ZIP/TUTOR.ZIP/TUTOR.LHI

Text File | 1996-05-20 | 19KB | 438 lines

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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.