计算机科学论文代写 User Interfaces Ic Compiler

计算机科学论文代写 User Interfaces Ic Compiler

5.8 Performing Power Planning

After completed the design planning process and have a complete floorplan, one can perform power planning, as explained below.

• Creating Logical Power and Ground Connections:

To define power and ground connections, use the connect_pg_nets command.

• Adding Power and Ground Rings:

It is necessary to add power and ground rings after doing floorplanning.

To add power and ground rings, use the create_rectangular_rings command.

• Adding Power and Ground Straps:

To add power and ground straps, use the create_power_straps command.

• Prerouting Standard Cells:

To preroute standard cells, use the preroute_standard_cells command.

• Performing Low-Power Planning for Multithreshold-CMOS Designs:

One can perform floorplanning for low-power designs by employing power gating. Power gating has the potential to reduce overall power consumption substantially because it reduces leakage power as well as switching power.

• Performing Power Network Synthesis:

As the design process moves toward creating 65-nm transistors, issues related to power and signal integrity, such as power grid generation, voltage (IR) drop, and electromigration, have become more significant and complex. In addition, this complex technology lengthens the turnaround time needed to identify and fix power and signal integrity problems.

By performing power network synthesis one can preview an early power plan that reduces the chances of encountering electromigration and voltage drop problems later in the detailed power routing.

To perform the PNS, one can run the set of following commands. [16]

synthesize_fp_rail

set_fp_rail_constraints

set_fp_rail_constraints -set_ring

set_fp_block_ring_constraints

set_fp_power_pad_constraints

set_fp_rail_region_constraints

set_fp_rail_voltage_area_constraints

set_fp_rail_strategy

• Committing the Power Plan:

Once the IR drop map meets the IR drop constraints, one can run the commit_fp_rail

command to transform the IR drop map into a power plan.

• Handling TLUPlus Models in Power Network Synthesis:

Power network synthesis supports TLUPlus models.

set_fp_rail_strategy -use_tluplus true

• Checking Power Network Synthesis Integrity:

Initially, when power network synthesis first proposes a power mesh structure, it assumes that the power pins of the mesh are connected to the hard macros and standard cells in the design. It then displays a voltage drop map that one can view to determine if it meets the voltage (IR) drop constraints. After the power mesh is committed, one might discover “problem” areas in design as a result of automatic or manual cell placement. These areas are referred to as chimney areas and pin connect areas.

To Check the PNS Integrity one can run the following set of commands.

set_fp_rail_strategy -pns_commit_check_file

set_fp_rail_strategy -pns_check_chimney_file

set_fp_rail_strategy -pns_check_chimney_file pns_chimney_report

set_fp_rail_strategy -pns_check_hor_chimney_layers

set_fp_rail_strategy -pns_check_chimney_min_dist

set_fp_rail_strategy -pns_check_pad_connection file_name

set_fp_rail_strategy -pns_report_pad_connection_limit

set_fp_rail_strategy -pns_report_min_pin_width

set_fp_rail_strategy -pns_check_hard_macro_connection file_name

set_fp_rail_strategy -pns_check_hard_macro_connection_limit

set_fp_rail_strategy -pns_report_min_pin_width

• Analyzing the Power Network:

One perform power network analysis to predict IR drop at different floorplan stages on

both complete and incomplete power nets in the design.

To perform power network analysis, use the analyze_fp_rail command.

To add virtual pads, use the create_fp_virtual_pad command.

To ignore the hard macro blockages, use the set_fp_power_plan_constraints command.

• Viewing the Analysis Results:

When power and rail analysis are complete, one can check for the voltage drop and electromigration violations in the design by using the voltage drop map and the electromigration map. One can save the results of voltage drop and electromigration current density values to the database by saving the CEL view that has just been analyzed.

• Reporting Settings for Power Network Synthesis and Power Network Analysis Strategies:

To get a report of the current values of the strategies used by power network synthesis

and power network analysis by using the report_fp_rail_strategy command. [16]