Cadence Tutorial : 8-bit Ripple Carry Adder Schematic & Symbol

1. Invoke icfb program.

%icfb &
- You will see the CIW windows open as shown in Fig 1.
2. Create adder8 library.

File->New->Library
In New Library window,
• Name : Adder8
• Technology File : Don't need a techfile (on the right window)
See Fig 2.

1. Open schematic window.

File->New->Cellview
In Create New File window,
• Library Name : Adder8
• Cell Name : inverter
• View Name : schematic
• Tool : Composer-Schematic
See Fig 3.
- You will see schematic window open as shown in Fig 4.
2. Place nmos transistor.

sch:Add->Component (or "i")
Add Component:click Browse
In Library Browser window,
• Library : tsmc25Lib
• Cell : nfet3
• View : symbol
See Fig 5.

 When you move mouse into schematic window, nfet3 symbol will follow your pointer.
Click "mouse L" to place nfet3. ("mouse R" will rotate nfet3 symbol in clockwise.)
Type "Esc" to exit adding component action.
See Fig 6.

3. Place pmos, vdd, and gnd.

- Repeat above procedure for pfet3, vdd, and gnd placement. All components can be found at the same library (tsmc25Lib or basic). See Fig 7.
- While Library Browser is open, clicking pmos, vdd, and gnd in cell field will bring instances. (you don't have to type "Esc" each time.)
4. Connect each component using wires.

Place mouse pointer on one of the node you want to connect
sch:Add->Wire(narrow) (or "w")
Click "mouse L", drag to other node to connect, and click "mouse L" to finish.
- Repeat above procedure to finish wiring as shown in Fig 8.
- To make wire open node at one end (like input and output of inverter), double-click "mouse L"
5. Place pins.

sch:Add->Pin (or "p")
In Add Pin window,
• Pin Names : A X
• Direction : input
See Fig 9.

 Move mouse to place A pin at input of inverter, then click "mouse L".
In Add Pin window, change direction to output.
Place X pin at output of inverter.
See Fig 10.

6. Add pmos parameters. (W/L)

Click pfet3
sch:Edit->Properties->Objects (or "q")
In Edit Object Properties window,
 
• Width : pPar("pw")
• Length : pPar("pl")
• Click OK or Apply
• Repeat for nfet3 with width pPar("nw") and length pPar("nl").

Check and Save
sch:File->Check and Save

1. Open symbol window.

icds:File->New->Cellview
In Create New File window,
• Library Name : Adder8
• Cell Name : inverter
• View Name : symbol
• Tool : Composer-Symbol
See Fig 15.
- You will see symbol window open as shown in Fig 16.
2. Draw outline for inverter symbol.

Click line icon on left toolbox of symbol window and draw outline of inverter.
See Fig 17.
3. Finish outline by adding circle.

sym:Add->Shape->Circle
Click "mouse L" on the center of circle, drag and click "mouse L" again.
See Fig 18.
4. Place pins.

sym:Add->Pin (or "p")
In Add Pin window,
• Pin Names : A X
• Direction : input
• Type : square
See Fig 19.

 Move mouse to place A pin at input of inverter, then click "mouse L".
In Add Pin window, change direction to output.
Place X pin at output of inverter.
See Fig 20.

5. Add selection box.

sym:Add->Selection Box
In Add Selection Box window, click Automatic.
See Fig 21.
- Selection box is a boundary to select this symbol in a schematic which include the current symbol.
6. Add labels.

sym:Add->Label
In Add Label window,
• Label : [@instanceName]
See Fig 22.

 Place label.
See Fig 23.

 Repeat Add Label for parameterized attributes.
In Add Label window,

• Label : [@pw:pw=%:][@pl:/pl=%:]
See Fig 24. Comment: The figures have not been updated yet so do not get confused from the minor differences at the label.

 Place label.

 Repeat Add Label for parameterized attributes.
In Add Label window,

• Label : [@nw:nw=%:][@nl:/nl=%:]
Place label.

 See Fig 25. Comment: The figures have not been updated yet so do not get confused from the minor differences at the label.
 
 

7. Check and Save

sch:File->Check and Save

Draw schematic and symbol for the following components.
• 2-input NOR gate schematic : nor_2
• 2-input NAND gate schematic : nand_2
• 2-input XOR gate schematic : xor_2
• 2-input NOR gate symbol : nor_2
• 2-input NAND gate symbol : nand_2
• 2-input XOR gate symbol : xor_2

 

 
 
 
 
 
 
 

 In Add Property window,

• Name : pw
• Type : float
• Value : 10

1. Create schematic.

icds:File->New->Cellview
In Create New File window,
• Library Name : Adder8
• Cell Name : adder_slice
• View Name : schematic
• Tool : Composer-Schematic
Complete schematic.
See Fig 34.
2. Create symbol automatically.

sch:Design->Create Cellview->From Cellview
In Cellview From Cellview window,
• Library Name : Adder8
• Cell Name : adder_slice
• From View Name : schematic
• To View Name : symbol
See Fig 35.

 In Symbol Generation Option window,

• Left Pins : CIN
• Right Pins : COUT
• Top Pins : A B
• Bottom Pins : SUM
See Fig 36.

 - This will display symbol window as shown in Fig 37.
- Edit symbol as shown in Fig 38. (Not necessary)
 
 

1. Create schematic.

icds:File->New->Cellview
In Create New File window,
• Library Name : Adder8
• Cell Name : adder8
• View Name : schematic
• Tool : Composer-Schematic
2. Place adder_slice.

See Fig 39.
3. Draw wires.

See Fig 40.
4. Draw buses.

See Fig 41.
- Use Add->Wire(wide) (or "W")
5. Add wire labels on A bus.

sch:Add->Wire Name
In Wire Name window,
• Names : A<7:0>
• Bus Expansion : on
See Fig 42.

 Place label on each wire
See Fig 43.

6. Repeat for B and S buses.

See Fig 44.
7. Add pins and complete schematic.

See Fig 45 and Fig 46.
8. Check and Save

sch:File->Check and Save