PowerView Tutorial : Inverter Schematic & Symbol

bug or comment to pgolani@usc.edu

Copy viewdraw.ini file.
%cp ~ee577/viewdraw.ini .

Execute ViewDraw program. See Fig 1.
%viewdraw &

Type inverter in "Enter name" field.
Then you will have a new schematic window. See Fig 2.

Get pmos from analog library. See Fig 3, Fig 4, and Fig 5.
Add->Analog->Transistors Click(rmb) pmoss from popup window Click(mmb) where you want to locate pmos

Repeat for nmos. See Fig 6.

Decrease sheet size.
Your current sheet size is too big for inverter schematic. Follow the next steps to decrease sheet size.
Change->Block->Size->Z-WxH... Width: 800 Height: 800
- If your transisors are out of box, zoom out the view by typing "F8"key. Then click and drag rmb to enclose both transistors. Type "m" to move and locate transistors on the center of sheet. See Fig 7.

Draw wires.
- Connecting elememnts. See Fig 8.
  Type "z", then drag rmb around transistors to zoom in Place mp(mouse pointer) on bottom of pmos Type "n" then drag mp to top of nmos Click mmb
- Open at one end. See Fig 9.
  Place mp on top of pmos Type "n" then drag mp to the point where you wish to terminate wire Double click mmb
- Finish wiring. See Fig 10.
  Ground symbol can be found at the same window of pmos and nmos.

Labeling.
- Global signal(Vdd). See Fig 11.
  Click rmb on Vdd wire Add->Label Label String : Vdd Visibility : Visible Scope : Global Sense : Notinverted Click OK Put mp on top of Vdd wire Click mmb to place label
  - Global scope makes power routing unnecessary. Your symbol doesn't have to include Vdd as a input port if you specify Vdd label as global.
  - Label in PowerView is case-insensitive.
- Local signal(In,Out). See Fig 12.
  Click rmb on In wire Add->Label or click mmb(clicking mmb will repeat the last execution - Add->Label) Label String : In Visibility : Visible Scope : Local Sense : Noninverted Click OK Put mp on top of In wire Click mmb to place label Repeat for Out
  - Make sure In and Out label have local scope.

Add attribute to pmos and nmos See Fig 13, Fig 14 and Fig 15.
Select pmos Add->Attribute Attribute : w=8 Click OK Place mp beside pmos and click mmb to locate attribute Repeat for l=2 attribute Repeat for bulk=Vdd attribute
- Select pmos means clicking lmb on pmos.
- Repeating to add attribute can be done by clicking mmb while pmos is selected.
- If you skip bulk attribute, bulk of transistor will be connected to source terminal when you extract hspice netlist. So, don't miss it.
- You may want bulk attribute to be invisible. Click "invisible" at "Add Attribute" window.
Another way to add attribute
Select nmos Type "Ctrl-A" BULK S : GND Drag scrollbar far below Type "W" in Name and "4" in Component Value Type "L" in Name and "2" in Component Value Steps below are only cleaner schematic purpose. Select "W=4" Click lmb on "L=2" while pressing "Ctrl" key - This will select L=2 with W=4 Type "m" then drag mp to place those selected attributes Select "bulk=gnd" attribute Change->Attr->Visibility Visibility : Invisible All or Selected : Selected Click OK - This will make "bulk=gnd" attribute invisible

For completed schematic, see Fig 16

Change attribute. See Fig 17.
- Change transistor name
  Select "M?" attribute of pmos Change->Attr->Value.. Type "MP0" or whatever you wish to be appeared in hspice netlist Click OK Repeat for nmos
- Change W or L attribute
  Select "W=8" attribute of pmos Change-Attr->Value.. Attribute value : 10 Click OK

Save.
File->Wite
- Make sure there is no errors or warnings.

Open symbol editor. See Fig 18 and Fig 19.
File->Open Enter name : inverter Click Symbols Click OK

Draw outline of inverter. See Fig 20 and Fig 21.
Add->Graphics->Line (or type "L") Click mmb and drag to another end of line Clicking rmb will escape from draw line mode Complete triangle as shown in Fig 20 Add->Graphics->Circle (or type "C") Click mmb at the center of circle Drag mp and click mmb to place circle as shown in Fig 21 Add->Graphics->Line

Add pins. See Fig 22.
Put mp on left side of inverter symbol Add->Pin (or type "p") Drag mp upto the edge of box Click mmb to place pin Repeat on right side
- Pin has different color(cyan) from green color of outline.

Add labels on pins. See Fig 23, Fig 24 and Fig 25.
Select In pin Add->Label Label String : IN Visibility : Visible (or Invisible) Scope : Local Sense : Notinverted Click OK Place label by clicking mmb Repeat for Out pin

Save.
File->Write Click "Press button to dismiss window"

Save schematic again.
File->Open->inverter.1 (schematic) File->Write (in schematic) Make sure there is no error or warning
- You need to write schematic again after creating symbol because schematic always search symbol and try to match input and output. Whenever symbol is drawn, save schematic again to verify design.

Practice yourself. See Fig 26
Draw the same nand gate schematic shown in Fig 26.

Copyright Joong-Seok "Jay" Moon

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