Magic Tutorial2 : Hierarchical Layout
bug or comment to jsmoon@usc.edu
- Make sure you have inverter layout
See Magic Tutorial -
Inverter Layout or download inverter.mag
file if you don't have.
- Execute magic program See Fig
1.
%magic ring
- Get inverter cell See Fig
2.
":getcell inverter"
- ":getcell" command can be abbreviated as ":getc". So you can type ":getc
inverter" instread.
- If inverter cell is not located at the center, type "v".
- Array it (5,1) See Fig
3.
":array 5 1"
- Another way to do See Fig 4
and Fig
5.
make sure you selected inverter cell.
get width of cell by
"b" - in command box, "Box height: 59, width: 22" will appear
":copy r
22"
repeat ":copy r 22" 3 more times by typing "." 3 times.
- Expand inverter cell(s) See Fig
6.
select one of the instances of inverter. (type "s" or
"f")
":expand" (type "x")
- When you have expanded the array, you can see that the paint in inverter
cells is displayed less brightly than in layout you have seen till now. This
indicates that inverter cell is not editable. (Currently, ring is editable
cell.) Any attempt to modify inverter cell is not acceptible at this level.
- To unexpand, type "X" or ":unexpand"
- Switching the edit cell See Fig
7.
select one of the instances of inverter.
":edit"
- Notice that the paint of inverter cell is brighter than one in Fig
6. This means that inverter cell is now editable.
- Any change in layout of inverter cell will affect the whole array.
- Change inverter size See Fig
8.
- Increase pmos width to 18 lambda and nmos width to 6 lambda.
- All of instances of inverter should be affected by this change.
- Save files
":write"
- It will ask you whether to save inverter and ring layout. Type "Enter"
(default action) to save files.
- Put labels on top layout See Fig 9,
Fig
10 and Fig
11.
select top cell(ring) and type ":edit"
"box(4,4)-> :paint
m1"
label Vdd on the drawn m1 layer
repeat for GND, z1, z2, z3, z4,
z5
- Any label (in, out) inside inverter instance cannot be seen from the top
cell. So you need to put labels on top cell.
- Base layer for top cell labels is required before labeling.
- Finish layout See Fig
12.
- For correct operation of ring oscillator, draw nmos and metal lines as
shown in Fig 12.
- Save.
":write"
- Run IRSIM or HSPICE simulation to check operation
Copyright Joong-Seok "Jay"
Moon
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