Saturday 18 August 2012

Timing Optimization Techniques


Timing Optimization Techniques are as follows:

1.Mapping :

Mapping converts primitive logic cells found in a netlist to technology-specific logic gates found in the library on the timing critical paths.

2. Unmapping:
Unmapping converts the technology-specific logic gates in the netlist to primitive logic gates on the timing critical paths.

3. Pin Swapping :
Pin swapping optimization examines the slacks on the inputs of the gates on worst timing paths and optimizes the timing by swapping nets attached to the input pins, so the net with the least amount of slack is put on the fastest path through the gate without changing the function of the logic.

4. Buffering:

Buffers are inserted in the design to drive a load that is too large for a logic cell to efficiently drive.
If the net is too long then the net is broken and buffers are inserted to improve the transition which will ultimately improve the timing on data path and reduce the setup violation.
To reduce the hold violations buffers are inserted to add delay on data paths.

5. Cell Sizing

Cell sizing is the process of assigning a drive strength for a specific cell in the library to a cell instance in the design.If there is a low drive strength cell in the timing critical path then this cell is replaced by higher drive strength cell to reduce the timing violation.

6. Cloning :

Cell cloning is a method of optimization that decreases the load of a very heavily loaded cell by replicating the cell. Replication is done by connecting an identical cell to the same inputs as the original cell.Cloning clones the cell to divide the fanout load to improve the timing.

7. Logic Restructuring

Logic restructuring means to rearrange logic to meet timing constraints on critical paths of design.

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