®
SoC Encounter™: Continuous Convergence (Flat and Hierarchical)
Version 3.3
March 3, 2004
SoC Encounter Course This course is flow-based. It draws heavily on Tcl commands to
implement the design. In this course, it is assumed that you know how to use the Encounter
engine and have some basic knowledge of the features of the Encounter platform. In this course, you will execute all the major steps required to
complete the design flow from gate level through place and route. You will fix signal integrity and timing problems using parasitic data
extracted with the Fire & Ice® extractor. You will run power analysis and view the IR drop in your design.
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Course Objectives In this course, you will Explore high-level and hierarchical design planning and virtual
prototyping. Run Amoeba and block placement. Route the design with Trial Route. Estimate parasitics and run delay calculation. Create clock trees. Run delay calculation. Optimize timing. Run final route. Extract parasitics. Run crosstalk analysis. Run power analysis. 3/3/04
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Course Agenda Day 1
Day 2
Introduction to the SoC
Top-Level Implementation
Encounter Environment
Chip Assembly and Sign-Off
Logical Synthesis and Scan
Chip Finishing
Insertion
Timing and Signal Integrity
Silicon Virtual Prototyping
Closure
Hierarchical Floorplan
IPO and Physical Optimization
Generation Detailed Block Implementation
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Postmask ECO Flow
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Customer Support and Documentation SourceLink® Online Customer Support
Customer Support
http://sourcelink.cadence.com Search the solution database and the entire site. Access all documentation. Find answers 24x7. Submit a service request online. Track a service request (SR).
If you don’t find a solution on the SourceLink site, you can send email or call customer support.
Service Request
E-mail E-mail
If your problem requires more than customer support, then a product change request (PCR) is initiated.
PCR
[email protected] [email protected]
R&D
You You can can send send aa service service request request by by e-mail. Include details and e-mail. Include details and data data or or pointers pointers to to the the data data to to illustrate illustrate the the problem. problem. If your request does not require that you send data for someone to analyze, then call the hotline.
1- 877- CDS 4911 (1- 877- 237- 4911) Quick access to support for questions, advice, or status checks. Support is available from 7:00 a.m. to 7:00 p.m., CST.
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®
Introduction to SoC Encounter
Module 1
March 3, 2004
Cadence Products at a Glance Encounter
Ensemble (+ standalone synthesis)
RTL/Datapath/ Low Power Synthesis
SE-PKS
PKS
BGX
Hierarchical partitioning
Virtual prototyping / Placement (Block/Cell)
First Encounter Ultra
SoC
Physical Optimization
PKS
Encounter
Nano Encounter
WRoute
SE-PKS SE-Ultra
Route Accelerator
SE-DSM
NanoRoute Ultra
NanoRoute
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Signal Integrity Sign-off Analysis
Celtic Analyzer
Sign-off Extraction and Power Analysis
Fire & Ice QXC, VoltageStorm
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The SoC Encounter Window Pull-Down Menus Toolbar Icons
Floorplanning Icons
Design Display Area Design Views Display colors
Satellite Window
Auto Query of Objects 3/3/04
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SoC Encounter Design Flow
Design Entry
Optimized Netlist Mapped Constraints
Logic Synthesis and Scan Insertion (BuildGates)
RTL Design Data Initial Constraints
Hierarchical Virtual Prototyping and Physical Implementation Environment (SoC Encounter)
Final Netlist Routed Database
Chip Finishing (VCE)
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SoC Encounter Design Flow
Design Entry Logic Synthesis/Scan Insertion Silicon Virtual Prototyping Hierarchical Floorplan Generation Detailed Block Implementation Top-Level Implementation BuildGates
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Chip Assembly and Sign-Off
SoC Encounter
Chip Finishing
Virtuoso/VCE
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®
Logic Synthesis and Scan Insertion
Module 2
March 3, 2004
Logic Synthesis and Scan Insertion RTL
Technology Libraries
RTL Design Entry and Constraint Definition
Constraints If you use PKS for preplacement optimization, then provide the floorplan.
Optimize/Map Netlist Design-For-Test Configuration Scan Insertion Custom WLM
Preplacement Optimization
Floorplan
Scan DEF Generation JTAG/BIST Generation Custom WLMs can be generated by the Encounter engine.
Netlist Generation Constraint Generation
Silicon Virtual Prototyping Netlist
Mapped Constraints
Scan DEF RC BG/PKS Third Party
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Logic Synthesis and Scan Insertion Steps Input Files RTL design data Timing constraints
Steps Optimize and Map the Design
An RTL description of a design can contain a mixture of high-level statements, gate-level netlists, and custom blocks. Use RTL Compiler (RC) tool to optimize and map the RTL. RTL Compiler is the next generation synthesis tool for multimillion-gate designs. DFT Configuration
Test synthesis is performed prior to and during optimization. Scan Insertion
The tool which inserts the scan components into the design will also output a scan order file. This file contains the order in which scan components need to be connected. 3/3/04
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Logic Synthesis and Scan Insertion Steps (continued) Preplacement Optimization Preplacement optimization is run before place-and-route to produce a more optimized netlist which is more likely to meet timing after place-and-route. You can use custom wire load models in subsequent runs of optimizations to use more realistic models than the generic wire load models which are typically used in the initial stages of synthesis.
Scan DEF Generation The Scan DEF file (scanDEF) is a subsection of the DEF file format. It is used to describe the scan chain configuration and the set of reorderable scan chains present in the netlist.
JTAG/BIST Generation JTAG (boundary scan) and BIST (built-in-self-test) components are used to isolate manufacturing defects in chips. JTAG/BIST generation is performed with third party tools.
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Logic Synthesis and Scan Insertion (continued) Output Files Optimized gate-level netlist Mapped constraints Scan order DEF file
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®
Silicon Virtual Prototyping
Module 3
March 3, 2004
Silicon Virtual Prototyping Netlist Timing and Clock Constraints
CTE TA (no net loading)* I/O, P/G Placement, or Flip Chip JTAG Placement Block Placement** Specify/Refine Floorplan
IO Placement
Silicon Virtual Prototyping Hierarchical Floorplan Generation
Vendor Floorplan
Detailed Block Implementation
Add/Delete/Modify
Top-Level Implementation
Module guides Fences (shaping/sizing)
Chip Assembly and Sign-off
Blockages (place/routing) Assign block locations Power plan
* Check constraints.
Amoeba Placement***
** Place top-level modules and blackboxes. (Used in an all-block design)
hardmacros and cells
Scan Chain Reordering Power Planning (rings/stripes)
Timing/Routing Issues
Trial Routing/Extraction/CTE Clock Issues
No
Clock Tree Synthesis
Timing Issues
Trial Routing/Extraction/CTE IPO Trial Routing/Extraction/CTE Power Analysis
Timing Issues Power Issues
***Depending on design size, you can use floorplanning mode or ClusteringPlace for increased capacity.
To Hierarchical Floorplan Implementation Floorplan / Fences
Timing/CTS Constraints SoC Encounter Optional
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Virtual Prototyping Steps To create a virtual prototype, complete the following procedure: Run timing analysis. Analyze timing with the Common Timing Engine (CTE) using zero net loading to determine whether the initial design meets timing requirements.
Place I/O, power, and ground pads. During this step, you have the option of reading a file that contains coordinates for pad placement or pad ordering information. You must include power and ground pads in the I/O file.
Place JTAG cells. Specify and place JTAG cells near the I/O cells. Once placed, they will not be moved in subsequent placement runs.
Place the blocks in the design if you have an all-block or channelless
design methodology. You can use the Encounter block placer or manually place blocks.
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Virtual Prototyping Steps
(continued)
Specify and Refine the Floorplan Defining Module guides and fences Define the initial placement guides for key modules. Guides tell the placer to place a specific module’s cells near the guide location. Alternatively, fences can be used. After a fence is created, components that belong to the fence will not be allowed to go outside the fence boundary.
Shaping and Sizing Fences Refine the shape and size of fences to align the fences manually, using relative placement to preserve relationships between fences and to keep fenced areas in specific locations. Correct the aspect ratio and size of the fenced areas. As an alternative, you can run the automatic block placer. The goal of this step is to make sure that when blocks are committed later in the process, you can successfully implement the blocks individually, and the design as a whole.
Adding Placement and Routing Blockages Add placement or routing blockages to clear routing channels in congested areas. For example, if there is heavy congestion around the corner of a block, add a placement blockage to relieve the congestion in that area. 3/3/04
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Virtual Prototyping Steps (continued) Refining the Floorplan Adjust block placement locations. Adjust block placement manually, if necessary.
Power plan. Optionally, define Multiple Supply Voltages (MSV), and define the power rings and power stripes. You can save the power plan to a file after achieving a satisfactory initial structure. Typically, you do this step only if you use a predefined power structure in the design.
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Virtual Prototyping Steps (continued) Run Amoeba placement. Use the Amoeba placer to place cells in the design. The placer places cells according to module guide and fence constraints. Running placement and analyzing the congestion lets you quickly gauge the feasibility of the design in meeting timing and placement density goals.
Reorder scan chains. Refine the initial scan-chain order based on Amoeba placement results. Although changes made at this step are not used after the initial floorplanning, this step is still recommended for reducing wire length for a more accurate analysis of congestion. Refine the initial scan-chain order based on the most recent Amoeba placement results.
Run power planning. Define the power rings and power stripes.
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Virtual Prototyping Steps (continued) Run trial routing. Use the trial router to route the design. Examine the congestion map and the report to identify congested areas. Use the prototyping option of Trial Route to gauge the routability of the design.
Extract RCs. Extract parasitic resistance and capacitance (RC) values to calculate delays based on the wire lengths determined by trial routing.
Analyze timing to find timing violations. Although timing at this stage is likely to have many violations, you can still discover useful information. Analyze the timing to determine how to alter the floorplan.
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Virtual Prototyping Steps (continued) Define clock tree constraints, such as insertion delay and skew limits. Synthesize the clock tree. Analyze the clock tree reports to determine if timing constraints have been met. At this stage, netlist changes are not passed forward. A clock tree is generated to determine clock and timing issues with the current floorplan.
Run trial routing, extract parasitics, and analyze timing. Run trial routing. Perform parasitic extraction to determine net RCs. Analyze the timing to determine whether the initial design meets timing requirements. If it does not, then rearrange the module guides. If timing issues remain after several floorplan iterations, you might need to change the RTL.
Run in-place optimization (IPO). Run in-place optimization, which adds buffer cells, resizes gates, and fixes design rule violations. Although netlist changes made at this stage are not kept, in-place optimization is necessary for assessing potential timing issues with the current floorplan.
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Virtual Prototyping Steps (continued) Run trial routing, extract parasitics, and analyze timing. If timing issues remain after several floorplan iterations, you might need to change the logical netlist. If no satisfactory floorplans are found, you might have to alter the RTL of the design.
Analyze power. Perform power analysis. Note that the power plan will be refined in the next procedure.
Save the floorplan. Save the floorplan file to pass to Floorplan Refinement.
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Virtual Prototyping Commands Use the loadConfig command to load the configuration file into the
SoC Encounter environment. The setCteReport command sets the report format to the Common
Timing Engine (CTE). When you run the buildTimingGraph command with the
-ignoreNetLoad option, you ignore the loading due to nets. The reportTA command generates a timing analysis report. Use the specifyJtag and placeJtag commands to specify and place the
Jtags in the design.
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Virtual Prototyping Commands (continued) Place the critical blocks in the design using the placeInstance
command. Instead of the placeInstance command, use the Move icon to move blocks and instances to the core area. Use the addRing and addStripe commands to create the power rings
and stripes around the core area and power rings around the blocks. Use the amoebaPlace command to place the cells and the blocks
which have not been preplaced. The -timingdriven option places the cells in timing-driven mode and requires a constraints file. Otherwise, the cells will be placed in congestion mode. Next, you create floorplan guides, which you might later convert to
fences. The command to create guides is createGuide. After placement, you can run trial route and extraction using the
trialRoute and extractRC commands. View the congestion map to determine if there are any hot spots in your design that might lead to routing problems downstream. 3/3/04
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Virtual Prototyping Commands (continued) If there are timing violations, you can run In-Place Optimization using
setIPOMode and fix the violations using fixSetupViolation. After fixing setup violations, run clocktree synthesis. First specify the
clock tree synthesis file, and run clock tree synthesis using the ckSynthesis command. After checking setup and hold time with the actual clock (instead of the
ideal clock) you can run power analysis to analyze the power consumption and IR drops in the design, using the updatePower and displayRailAnalysisResults commands. Finish the virtual prototyping stage by saving the design and the
floorplan with the saveFPlan and saveDesign commands.
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Lab Exercises Lab 1-1 Virtual Prototyping
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®
Hierarchical Floorplan Generation
Module 4
March 3, 2004
Hierarchical Floorplan Generation Flow Partition Clock and Timing Constraints
Initial Netlist
SVP
Physical Partition Definition
Silicon Virtual Prototyping
Amoeba Placement Fenced Floorplan
Trial Routing Parasitic Extraction/CTE TA
Timing or Congestion Problem
Hierarchical Floorplan Generation Detailed Block Implementation
IPO with -honorPartition
Top-Level Implementation
Trial Route (use -honorPartition)
Pin Optimization Time Budget
Parasitic Extraction/TA
Push Down Power
Power Routing
Chip Assembly and Sign-off
Timing Problems
LEF Generation
Power Problems
TLF/STAMP Generation
Power Analysis
Top-Level Implementation Top-Level Netlist Block LEF(s)
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Floorplan Placement
Commit Partitions Save Partitions
Detailed Block Implementation Block Netlist
Block TLF(s)
Budgeted Constraints
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Floorplan/ Placement Boundary Voltages
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Inputs to Hierarchical Floorplan Generation The following information is needed for this stage: Initial netlist Timing and block constraints Fenced floorplan
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Hierarchical Floorplan Generation Steps Define the physical partitions. Change fences to partitions.
Run Amoeba placement. Run timing-driven placement based on the partitions you defined. This will
place the remaining cells at the top level of the design. Run trial routing, extract parasitics, analyze timing. Route signals based on partitions, and examine the congestion map. If
congestion is acceptable, proceed to extract parasitics. If congestion is unacceptable, refine the floorplan by beginning with detailed block placement. Extract parasitic RC values to calculate delays based on the wire lengths
determined by trial routing. Analyze timing using CTE to determine whether the floorplan, based on
the partitions you chose, meets timing constraints. If timing constraints are met and congestion is acceptable, commit the partitions. If they are not met, go back and refine the floorplan. 3/3/04
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Hierarchical Floorplan Generation Steps (continued) In-Place Optimization (IPO) To create the best budgets for the blocks, the design is run through IPO to
optimize the timing. The IPO option -neverAddPort will run IPO without creating any additional module ports. Use this option to avoid changes to the block port lists at this stage. Run trial routing, extract parasiitics, analyze timing. The design is routed, extracted and timed again.
Route power. Power is routed to the blocks and the components.
Analyze power. Power analysis must be done prior to partitioning so that power budgets
can be created for the partitions.
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Hierarchical Floorplan Generation Steps (continued) Commit Partitions Make a final decision on the partitions to implement as separate blocks.
Committing partitions creates fences, which constrain the module to a specific location without making a final commitment to the location. Committing partitions automatically does the following: Optimizes pins.
For each block, the pin optimization places pins along the edges of the block. The pin optimizer uses trial routing to determine the optimal pin placements.
Creates the timing budget.
Distributes timing delays: latch-to-pin within modules and pin-to-pin between modules.
Pushes power into blocks.
Pushes stripes and rings down into the blocks. The blocks inherit the power structure from the top-level floorplan.
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Hierarchical Floorplan Generation Steps (continued) Save Partitions When the partitions are saved, a directory for each block is created. Its
netlist, floorplan, and budgeted constraints are saved in the directory. The cell placements within the partitions can optionally be saved as well. A directory is also created for the partitioned top level. The top-level
netlist, floorplan, and updated constraints are saved into it. In addition, a simple timing model (STAMP) and LEF model is generated to represent each block that is instantiated in the netlist.
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Hierarchical Floorplan Generation Commands In addition to the commands in the Silicon Virtual Prototyping stage the following commands are used in Hierarchical Floorplan Generation: The createPartition command changes the guides to fences for the
specified module of a hierarchical design. The createPtnCut creates partiton cuts so that core rows are cut out
from the partition area at the top level. The partitionPlace command runs a two-phase placement to better
handle the partition flow to assign pins more accurately and reduce the routing congestion. After committing the partitions, save the partitions using the
savePartition command. Saving the partitions saves the timing and LEF models in the partition directory.
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Results of Hierarchical Floorplanning The following data is generated for top-level floorplan implementation: Block LEFs Block timing models Top-level netlist Top-level block placement Top level timing constraints
The following data is generated for detailed block implementation: Block netlist Floorplan and placement information Budgeted timing constraints Boundary Voltages 3/3/04
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Lab Exercises Lab 2-1 Implementing the Hierarchical Floorplan
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®
Detailed Block Implementation
Module 5
March 3, 2004
Detailed Block Implementation Flow From Hierarchical Floorplan Generation Block Netlist
Budgeted Constraints
Floorplan/ Placement
Timing-Driven Placement Scan Chain Reordering Trial Route/ Parasitic Extract/CTE
High Effort IPO Congestion Optimization
Difficult Timing
Slew Balancing IPO Clock Tree Synthesis Trial Route/Parasitic Extract/CTE
High Effort IPO Skew Clock Post CTS
Celtic Encounter
Physical Optimization Flow
NanoRoute Sign-off extractor
Trial Route/Parasitic Extract/CTE
TD Route with SI awareness Extraction* Timing/SI Closure Flow Power Grid Analysis
SI Closure
Noise Model Generation Output DEF, GDS or OA, Netlist and Spef Timing Model Creation Equiv. Check
Sign-off Power Grid Analysis Equivalence Checker Optional Step
* SoCE Detailed extraction with -assumeMetalFill.
To Top-Level Implementation Timing Model Noise Model
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Power Model
To Chip Assembly and Signoff DEF
Netlist
SPEF
GDSII
LEF OA
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Inputs to Block Implementation Block netlist Timing and clock constraints for the block Floorplan and placement information Boundary voltage for VoltageStorm® power analysis
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Block Implementation Steps Run Amoeba placement. After starting a new session in the block directory, read in the block netlist and floorplan. Use the constraints from Hierarchical Floorplan Generation and place the block in timing-driven mode.
Reorder scan chains. Reorder scan chains to relieve routing congestion.
Run trial routing, extract parasitics, and run timing analysis. The block is routed and extracted. Then, the timing of the block is analyzed. For blocks with very difficult timing, you might have to run PKS (physical synthesis) to optimize and restructure the netlist.
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Block Implementation Steps (continued) Run high-effort in-place optimization (IPO). Run congestion optimization. Running the congOpt command affects placement and has the benefit of preventing downstream signal integrity (SI) issues.
Balance slews. Balancing slews is a part of the flow that prevents SI problems by upsizing or downsizing components that are close to each other. This process minimizes the effect of aggressor on the victim due to differences in their slew rates.
Run high effort IPO again. Synthesize the clock trees in the block. Select the option to generate a Macro model for the block when synthesizing the clock tree. The information in the Macro model file contains the insertion delay for the block that will be used later when implementing the top level.
Run trial routing, extract parasitics, and run timing analysis. The block is trial routed, extracted, and the timing is again analyzed, this time with propagated clocks.
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Block Implementation Steps (continued) Run high-effort in-place optimization (IPO). When you run IPO with the -highEffort option, physical synthesis optimization commands run on paths with timing closure challenges.
Do a useful skew analysis and implementation for paths whose timing
is hard to close with IPO. Post-CTS useful skew performs time-borrowing by inserting buffers/inverter pairs or resizing cells on clock nets.
Run trial routing, extract parasitics, and run timing analysis. Run routing with signal integrity options. The NanoRoute tool will use soft spacing as a method to prevent long wire from running next to each other, thus reducing the possibility of crosstalk effects.
Run extraction. Go to the timing/signal integrity closure subflow.
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Block Implementation Steps (continued) Run power analysis. Assuming that the netlist is clean, use the Encounter engine to run a power analysis, and then use the VoltageStorm power analyzer to run an IR drop analysis. At this point, the block is essentially complete and the rest of the steps involve creating various representations of the block to use during top-level implementation and chip assembly.
Create an Echo model. To create an Echo noise model for the block, run the CeltIC tool in the Encounter engine or in standalone mode.
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Block Implementation Steps (continued) Generate LEF, DEF, GDS/OA, netlist, and SPEF. The Encounter tool can directly generate a GDSII representation of the block. In addition, it can also create an OpenAccess (OA) database for the block. The database can be read by the Virtuoso Chip Editor (VCE) during chip assembly in place of the GDSII. A block power model, consisting of a power grid model and a power consumption value, can be created to represent the block during top-level power analysis.
Create a timing model. Create a detailed and characterized TLF or .lib blackbox timing model of the block. The STAMP model that was created during partitioning in the hierarchical floorplan generation was only a simple one-dimensional representation of the block and contained no load- or slew-dependent timing information.
Run an equivalence check. Because the netlist has been modified, run a formal verification tool to ensure that the changes that were made did not change the logic or the functionality of the netlist.
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Block Implementation Commands To fix setup violations, use the IPO command fixSetupViolation. If there are hold violations, fix them by running fixHoldViolation. If timing does not converge using the IPO commands in –highEffort
mode, run the runPhySyn command on the design. Report and optimize leakage power by running reportLeakagePower
and optLeakagePower. Optimize the clock tree for the block and save the clock tree macro
model using the ckSynthesis command and the -macromodel option. The saved macro model will be used later in top-level clock tree synthesis. Add filler cells using the addFiller command. Use NanoRoute to route the critical nets first, and then route the
remaining nets. The globalDetailRoute command runs NanoRoute.
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Block Implementation Commands (continued) Add metal fill using the addMetalFill command. Verify the geometry,
connectivity and antenna to make sure that the addition of filler cells and metal fill did not violate any design rules. The verification commands are verifyConnectivity, verifyGeometry and verifyProcessAntenna. Fix block-level crosstalk violations using fixCrosstalk. Extract the block by using the Fire & Ice® runQX command. Generate the .lib or TLF timing model and the OpenAccess database
for the block using the genTlfModel and oaOut commands.
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Output of Block Implementation The result is a placed and routed block. The output files are: DEF file Verilog® netlist LEF file SPEF file OpenAccess database Timing Model Power Model Noise Model GDSII file 3/3/04
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Lab Exercises Lab 3-1 Detailed Block Implementation
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®
Top-Level Implementation
Module 6
March 3, 2004
Inputs to Top-Level Implementation Top-level netlist Floorplan and hard block placements Top-level constraints
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Top-Level Implementation Import Block Model Data
From Hierarchical Floorplan Generation Top Level Netlist
Floorplan
Constraints
Timing-Driven Placement Scan Chain Reordering Trial Route/Parasitic Extract/CTE High effort IPO
From Block Implementation Antenna Models
Timing Models
Power Models
Noise Models
Repeater Insertion Congestion Optimization Slew Balancing IPO Useful Skew pre-CTS CTS Trial Route/Parasitic Extract/TA High effort IPO Skew clock post-CTS Trial Route/Parasitic Extract/TA TD Route with SI awareness Extraction* Hier Timing/SI Closure Flow Hier Power Grid Analysis
SI Closure SI Analysis and Repair
Output top-level DEF, GDS or OpenAccess, Netlist and Spef Equivalence Check
Celtic Encounter
Difficult Timing
NanoRoute Sign-off extractor Sign-off Power Grid Analysis
Physical Synthesis
Equivalence Checker Optional Step
* SoCE Detailed Extraction with –assumeMetFill
To Chip Assembly and Sign-Off DEF
Netlist
SPEF
GDSII
OA
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Top-Level Implementation Steps Import the Block LEF files. Update the configuration file to import the block LEFs. Run Amoeba placement. Run placement on the top level, leaving block placement fixed. Re-order the scan chains. The placed scan chains at the top level are re-ordered to relieve routing congestion. Run trial routing, extraction, and CTE timing analysis. The top level is routed and extracted. The timing is analyzed. Use a sign-off extractor to extract top-level parasitics. Signal integrity and timing optimization are done simultaneously by the Encounter engine. Leakage power is also optimized by resizing gates in this step. Run high effort IPO. Insert repeaters. Repeaters are inserted after crosstalk prevention has been implemented. Run congestion optimization. Balance slews. 3/3/04
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Top-Level Implementation Steps Run high-effort in-place optimization (IPO). Run high-effort IPO with restructuring to fix setup and hold violations.
Run Useful Skew Pre-CTS. Run clock tree synthesis. Do trial routing, extract parasitics, and analyze timing. The design is trial routed, extracted, and timing is again analyzed – this time with propagated clocks.
Run high-effort IPO. Do clock skew. Do a useful clock skew post CTS.
Run trial routing, extraction and timing analysis Run routing with signal integrity. The NanoRoute tool runs signal integrity and timing-aware detailed routing. This tool is integrated natively into the Encounter executable and runs from the same in-memory data structures. 3/3/04
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Top-Level Implementation Steps (continued) Extract the design. Extract the design using either the Encounter detailed extraction or the Cadence® Fire & Ice® QX extractor. Both are available in the Encounter cockpit.
Run the timing optimization and signal integrity subflow. Run a hierarchical power grid analysis. Run power and an IR drop analysis using the Encounter or VoltageStorm® tools. The VoltageStorm tool requires an additional license.
Generate top-level GDSII/OpenAccess, DEF, Verilog® netlist, and
SPEF. At this point, the top level is essentially complete. An OpenAccess (OA) database and GDSII file can be created for the top level. The database can be read by DFII during chip assembly instead of the GDSII.
Run an equivalence check.
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Example of Repeater Rule file Command insertRepeater {-rule ruleFile | -template} [-selNet selNetFile] [-excNet excNetFile] Example Rule File # Buffer Drive Strength Cell Max Wirelength Total Cap # Name Microns pF SetBufferDrivingStrength BUFX16 1200 2.5 SetBufferDrivingStrength BUFX20 1500 3.0 SetInvertorDrivingStrength INVX20 1500 3.0 # Block Output Drive Strength (Optional to customize) SetCellDrivingStrength alu 50 0.5 SetCellDrivingStrength rpt_blk 2500 5.0 # Block Input Load (Optional to overwrite timing library values) SetCellReceiverLoad alu 50 0.05 SetCellReceiverLoad rpt_blk 50 0.05 # Default Block Drive Strength SetDefaultDrivingStrength 2000 4.0 3/3/04
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Output of Top-Level Implementation The result is the placed and routed design and these outputs: Top-level GDSII Top-level netlist Top-level SPEF Top-level DEF Top-level OpenAccess database
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Lab Exercises Lab 4-1 Top-Level Implementation
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®
Chip Assembly and Sign-Off
Module 7
March 3, 2004
Chip Assembly and Sign-Off From Block Implementation
From Top-Level Implementation Top-Level DEF Top-Level Netlist
Flatten (unpartition) Full-Chip Power Grid Analysis
Block DEFs
Silicon Virtual Prototyping Hierarchical Floorplan Generation
Block Netlists
Detailed Block Implementation
Full-Chip Parasitic Extraction
Top-Level Implementation
Full-Chip SPEF Top-Level SPEF
Stitch
Chip Assembly and Sign-off
Stitching SPEF or Flat SPEF
Block SPEFs
Full-Chip Timing Analysis Celtic Encounter Sign-off extractor Sign-off Power Grid Analysis
Full-Chip SI Analysis
Timing Constraints
Full-Chip SDF
Full-Chip Timing Simulation
To Chip Finishing Use SignalStorm for delay calculation.
Top-Level OA
Top-Level GDSII
Block OA’s
Block GDSII
NC Verilog Optional Step
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Inputs to Chip Assembly and Sign-off At this stage, you bring together the top-level and block-level design information to flatten the design and to run a final analysis. Inputs Top-level DEF Block-level DEF Top-level netlist Timing constraints Block netlist Full-chip DEF
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Chip Assembly and Sign-Off Steps (Optional) Flatten the design. Flatten the design by merging the top-level and block-level DEF files.
Run a full-chip power analysis. Use the VoltageStorm® tool to perform a power analysis.
Extract full-chip parasitics (optional). Use the Fire & Ice® QX extractor to run a flat extraction to derive all parasitics, including potentially undetected coupling between routing at the top-level and in the blocks. Either a 64-bit full-chip parasitic extraction can be performed on the flattened design, or the SPEFs from the top level and the blocks can be stitched together for 64-bit timing and SI analysis.
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Chip Assembly and Sign-off Steps (continued) Run a full-chip timing analysis. Use the Encounter engine in CTE mode to analyze the timing. You can run either a fullchip extraction on the flattened design, or stitch the SPEFs from the top level and the blocks together for timing and signal integrity analysis.
Run a full-chip crosstalk analysis. In the Encounter engine, read the SPEF file generated by the extractor, the top-level netlist, the timing constraints file, and the netlists for all the blocks. Use the CeltIC tool to run a full-chip crosstalk analysis.
Generate a full-chip OpenAccess database. Generate the OpenAccess database files using the oaOut command.
Generate a full-chip SDF file (optional). If the methodology calls for dynamic simulation in the sign-off process, an SDF file can be produced to feed the NC-Verilog® simulator.
Run a full-chip timing simulation (optional). Run a full-chip timing simulation if possible. 3/3/04
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Chip Assembly and Sign-Off Commands If the design is hierarchical, one of the main steps at this stage is to
flatten the database. To flatten the database, you need to unpartition the design using the flattenPartition command. You can then run extraction, delay calculation, SI analysis, and power
analysis on the flat design.
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Outputs of Chip Assembly and Sign-off The outputs of chip assembly and sign-off include: Full-chip Verilog netlist Top-level GDSII Block-level GDSII Full-chip OpenAccess database
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®
Chip Finishing
Module 8
March 3, 2004
Chip Finishing From Chip Assembly and Sign-Off
Block OA’s
Top-Level OA
Import Top and Block OA DBs
* Modified OA DB
*Non Connectivity Modifying edits
Top-Level GDSII
Block GDSII
Import Top and Block GDSII
Need to import either OA DBs or GDSII
Import Std Cell GDSII/OA Layout Finishing/Editing Physical Verification
Restore OpenAccess Design
Errors?
Yes
Verify/Extract/TA Encounter
* Modified OpenAccess database can be read back into SoC Encounter.
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RTM GDS
VCE Assura
Optional Step
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Inputs to Chip Finishing Import one of the following formats into Virtuoso® Chip Editor (VCE) or a layout editing tool to complete the flow: Top-Level GDSII and Block-Level GDSII Top-Level OpenAccess database and Block-Level OpenAccess
database Full-Chip OpenAccess database
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Chip Finishing Steps Import the GDSII layouts for the standard cells into a DFII database. Import the OpenAccess databases or GDSII files for the top level and
for the blocks, or import the full-chip OpenAccess database. Run layout finishing. Layout finishing steps include adding scribe lines, adding fiducials, adding alignment marks, and adding test fixtures.
Run physical verification. After the layout finishing steps are complete, run a sign-off-level physical verification with Assura to look for any design rule violations. If any are found, they can be corrected in Virtuoso® and the layout finishing steps might need to be redone. When the design passes error free, then masks can be generated and the chip fabricated.
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SoC Encounter
VCE Flow Steps
Library Creation for VCE Use the lefin program (the DFII version of lef2oa) needs to create correct
techfile information and abstract cellviews for VCE. Complete your design in SoC Encounter. Save the floorplan file. Needed when restoring design in SoC Encounter.
Output an OpenAccess database from the Encounter environment. Open the OpenAccess database in VCE. Edit the database in VCE.
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SoC Encounter
VCE Flow Steps (continued)
Save the OpenAccess database in VCE. Import a design in SoC Encounter. Restore floorplan from the previous Encounter session. Clear floorplan to remove any special routing (power, ground, signal). Load the OpenAccess database from VCE into SoC Encounter to
update wiring and placement. Use the Encounter commands for verification, timing analysis, and
other tasks. Repeat loop as required. You can produce a GDSII stream from either VCE or SoC Encounter. Usually VCE is used, because the GDSII stream file needs to include
scribe info and other data that typically does not exist in the Encounter database. 3/3/04
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Lab Exercises Lab 5-1 Chip Assembly and Sign-Off
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®
Timing and Signal Integrity Closure
Module 9
March 3, 2004
Timing and Signal Integrity (SI) Closure Flow Extracted Design w/Metal Fill Assumed in Extraction
Timing Analysis Setup/Hold IPO fixSetupViolations IPO fixHoldViolations SI-Aware ECO Route SI Analysis Fix Crosstalk Add Filler Cells (postroute) Wire Editing Add Metal Fill Fill Notch Verify Metal Density Verify Geom./Conn./Ant. Detailed Extraction SI Analysis Timing Analysis Setup/Hold
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Timing and Signal Integrity Closure Steps Run timing analysis to determine if there are violations in your design. Run in-place optimization and fix setup and hold violations. Set the IPO mode using the setIPOMode command. You can set the mode to -highEffort, which will automatically call synthesis optimization transforms to meet timing. Use fixSetupViolation and fixHoldViolation to fix timing violations in your design. Syntax initECO ipo.txt fixSetupViolation endECO Bracketing the IPO commands with the initECO and endECO commands will log the changed components in the ipo.txt file. Run a signal integrity-aware ECO route using NanoRoute. Run a signal integrity (SI) analysis. Fix crosstalk. Use the fixCrosstalk command in signoff mode to run the CeltIC™ and NanoRoute™ tools to iteratively analyze and fix the signal integrity violations in the design. Fixing crosstalk involves fixing glitches and also the delay due to noise. 3/3/04
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Timing and Signal Integrity Closure Steps (continued) Add filler cells.
Adding filler cells after routing will not cause DRC violations in the design because the tool will analyze potential violations before selecting the appropriate filler cells from the physical library. Use the addfiller command to add filler cells to your design.
Add metal fill.
Use the addMetalFill command with the -layer option.
Fill notches.
Filling notches at this stage is necessary to prevent errors downstream in tools which check masks for notches and gaps.
Verify metal density. Verify geometry, connectivity, and antenna.
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The verifyConnectivity, verifyGeometry and verifyProcessAntenna commands generate markers and error logs of the DRCs in the design.
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Timing and Signal Integrity Closure Steps (continued) Extract the design using the Fire & Ice® QXC tool. Assume metal fill for
the extraction. Run a signal integrity-aware ECO route using the NanoRoute tool. Run a timing analysis and fix setup/hold times.
Command Syntax for IPO and Timing Closure setIPOMode –high fixSetupViolation fixDRCViolation fixHoldViolation
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Timing and Signal Integrity Closure Steps (continued) Signal Integrity Closure Commands The fixCrosstalk command performs an incremental or signoff SI
analysis, repair, and RC extraction based on the options that you specify. The fixGlitchViolation command creates a violation file for SoC
Encounter to fix. The fixNoiseDelay command fixes the delta delay caused by noise.
This command takes timing into consideration.
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IPO and Physical Optimization
Module 10
March 3, 2004
Physical Optimization Flow From Block or TopLevel Implementation Placement
Netlist
Constraints
Run through SoCE/PKS Interface
Full PKS Optimization Capabilities
Create Path Groups Pre-Clock Optimization Clock Tree Synthesis Useful Skew Optimization
Standalone PKS
TD Global Route IPO TD Global Route IPO Setup/Hold Fixing
PKS Encounter
To Block or Top-Level Implementation Routed DEF
Optimized Netlist
NanoRoute Sign-off extractor
SPEF
Equivalence Checker Optional Step
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Physical Optimization Flow (continued) From Block or TopLevel Implementation Placement
Netlist
Constraints
Run through SoCE/PKS Interface
Full PKS Optimization Capabilities
Create Path Groups Pre-Clock Optimization Clock Tree Synthesis Useful Skew Optimization
Standalone PKS
TD Global Route IPO TD Global Route IPO Setup/Hold Fixing
PKS Encounter
To Block or Top-Level Implementation Routed DEF
Optimized Netlist
NanoRoute Sign-off extractor
SPEF
Equivalence Checker Optional Step
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Optimization Transforms Full set of logical synthesis transforms are available in conventional synthesis, including:
LEF,.lib, .alf, .tlf
RTL/ Gate-Level Netlist
Timing Constraints
DEF/ PDEF
Restructuring Cloning Buffering
Parsing, Structuring, Mapping
Resizing
Initial Placement
Each optimization is incrementally placed, routed, and timed.
PKS
Optimization Transforms restructure, clone, resize, buffer, etc.
Allows millions of logical and
physical tradeoffs against highly accurate timing.
Incremental Placement Time using Steiner Route
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accept/reject
If placement is not possible,
Placement Legalization
logic change is rejected.
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Group Paths By default, PKS optimization works on one path at a time. The path
worked on is the one with worst slack. Hence if a path is over constrained, the remaining paths are not optimized. Group path command distributes paths into different groups, and the
path with the worst slack in each group is now optimized. All paths originally start in the default group (default). Translator will now automatically translate Synopsys group_paths
command to the BuildGates equivalent Tcl command. Example set_path_group –name IO –from [find –input]
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Physical Optimization Steps Create the path groups. Path groups are recommended to isolate specific areas of the design. This
helps to assist in uncovering areas that are prone to closure issues and allows the optimizer to close timing on the rest of the design. Run preclock optimization. Run pre-CTS useful skew. Run clock tree synthesis. Synthesize the clock tree. Analyze the clock tree reports to determine if
constraints have been met. Run a useful skew optimization.
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Physical Optimization Steps (continued) Run timing-driven global routing. Global routing creates the route plan for the detail router. The extraction
and timing analysis at this stage will provide you with an accurate picture of what to expect after detail routing. Do in-place optimization (IPO) if there are timing errors. Run the design through IPO to optimize the timing.
Rerun global routing. Because the netlist has been modified, the route plan has to be re-
created. Rerun in-place optimization, if there are violations.
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IPO Strategies IPO has two major phases: Global optimization phase (also known as weed-whacking) Transforms are applied to all violating nets/instances in a global pass.
Critical path fine tuning phase (high effort only) Transforms are applied to a small critical range of the violating
nets/instances
IPO refines placement, runs trial route, runs extraction, and updates timing at the end of each major step. Uses incremental trial route for better run times. Only nets touched by IPO are rerouted.
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Optimizing Setup Timing In SoC Encounter, IPO has three effort levels: Low effort This level performs changes, such as buffering long nets or resizing cells. This step is extremely fast and needs to be used at the prototyping stage.
Medium effort This level triggers more optimization process than -lowEffort does, and further optimizes the most critical paths. Its target is to get an accurate estimation of the design performance or to close timing on less challenging designs.
High effort You need to use this level to reach timing closure for challenging designs. It turns on all the physical synthesis optimization transforms.
Syntax setIPOMode -highEffort
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Optimizing Setup Timing (continued) There are two separate commands for Setup optimization. Setup timing optimization after placement setIPOMode -highEffort fixSetupViolation
Setup timing re-optimization setIPOMode -highEffort optCritPath
After each individual optimization step, fixSetupViolation performs placement legalization, routing, extraction, and timing updates.
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Fixing Setup Using IPO setIPOMode –low/-medium fixSetupViolation
Downsize
Resize
After each optimization step, placement legalization, routing, extraction, and timing update are performed.
Buffer insertion
Resize setIPOMode -high fixSetupViolation
optCritPath
Critical Paths Optimization using Physical Synthesis transforms
Use Model Use fixSetupViolation after placement. Use optCritPath for re-optimization.
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setIPOMode -usefulSkew Useful Skew
*
setIPOMode -reclaimArea
reclaimArea
Reclaim Area SoC Encounter
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Downsizing/Resizing Initial global pass downsizes gates without worsening violations. For medium and high effort, initial resizing does the following: What-if analysis for all candidates to be resized without committing the
resizes Order resize moves in decreasing order of gain Commit resize moves in above order, invalidating neighboring moves for
each committed move Iterate until number of moves found or slack improvement is negligible or
maximum # of pass (10) is reached Combinational and sequential resizing are done separately. A global sizing pass is run to improve DRVs. In high effort, second global sizing does a greedy input-to-output pass
with more accurate delay updating to guarantee no slack worsening.
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Buffering For each violating net, from input to output, The tool chooses a wire topology TrialRoute topology Topology based on physical clustering (similar to CTS)
Quick buffering is done for each topology assuming certain capacitive
load per buffer. The topology with the fewer number of levels of buffers is chosen. Buffering prefers trialRoute topology in case of tied results. Buffering determines which segment is not bufferable due to no-new-
port, and dont-touch constraints.
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The optCritPath Command Boolean restruct
pinswap deleteBuffer resize addBuffer resize
setIPOMode -highEffort
Each step operates on a 5%
critical range of the violations.
topoMap
The optCritpath command
optimizes the critical paths and stops when target slack is met or when timing cannot be optimized further. It tries to improve the worst
remapCone
mergeInverter
negative slack and you must use it each time you want to reoptimize a netlist. 3/3/04
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moveInstances
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Design Rules Violation Fixing DRV fixing is done during fixSetupViolation, and the remaining DRVs
can be cleaned using the fixDRCViolation command. The fixDRCViolation command will loop up to three times to fix the
DRV. Use -maxIter to specify the number of loops allowed. To check if DRVs are cleaned, use the isDRVClean command. Reports 0 or 1.
An extra pass of DRV fixing is run in global optimization phase (weed-
whacking). To report the DRV, use: reportTranViolation/reportCapViolation/reportFanoutViolation
Use bufferMultiDriverNet to fix all DRV on multidriver nets.
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Optimization Guidelines Creating a clean footprint file is important. No or bad footprint definitions leads to less than optimal IPO results. Use the checkFootPrint command after making a footprint file. Steps to making a footprint file: Generate a footprint file. Modify this file to specify the buffer, inverter, and delay cell footprints to
separate the cells that you don’t want to use. Load the footprint file.
The IPO process will also respect the set_dont_use attribute.
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Optimization Guidelines (continued) After running IPO, you must examine the remaining violating paths or DRV for the following possibilities: Be sure that the Worst path can meet your target slack. Use Path Group to further optimize the design. If there are remaining DRVs, then call fixDRCViolation. Check routability numbers from TrialRoute. Check the congestion map to see if worst paths are going through
local congestion hot spots. If there are congestion issues, then run placement in congestion-
driven mode followed by IPO. If there are timing issues, try IPO on a design that has been placed
using the -timingdriven option.
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Postmask ECO Flow
Module 11
March 3, 2004
Making Postmask Changes to the Design Reasons for Making Changes Base layers of the design have been taped out and you have found
logic errors. At the same time, you need to preserve the poly and diffusion layers that are already taped out. To fix the errors, you need to Route to pre-existing spare-cells. Change only metal and via layer masks by rerouting to spare cells.
You can create A new netlist with minor logical changes based on the old netlist
or A new ECO file
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Procedure: Postmask ECO with a New Verilog File To prepare for postmask changes spare cells could have been added to the netlist prior to generating a mask. There are two ways in which spare cells are added to the design: Spare cells are added to the original Verilog netlist. Spare cells are identified with this command:
specifySpareGate –inst mySpareInst Spare cells are added using a previous spare.eco file: ADDHIERINST mySpareInst mySpareCellName ADDINST mySpareInst/mySpareAnd_1 AND2 ATTACHTERM mySpareInst/mySpareAnd_1 IN1 VSS ATTACHTERM mySpareInst/mySpareAnd_1 IN2 VSS followed by loadECO spare.eco
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Postmask ECO with a New Verilog File Read old Verilog® floorplan, placement, routes files into the Encounter engine. Compare current netlist to new Verilog netlist to create an ECO file. ecoCompareNetlist -verilog new.v -outFile oldchip.eco The ECO file has all changes required to make the current netlist match the
new netlist.
Physical-only cells like filler cells are ignored.
Load the ECO file to update the current netlist to match the new netlist. loadECO -useSpareCells -suffix _SPARE oldchip.eco Instances that only appear in the old Verilog netlist are implicitly deleted by
leaving them in place and changing the name (i1/i2/i3 to i1/i2/i3_SPARE). The dangling inputs are attached to GND.
New instances are placed by using the nearest matching sparecell with the
same cell.
New ports are created on Verilog modules as needed. Routing on deleted nets is removed. Error messages are output for any unplaced cells. 3/3/04
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Postmask ECO with a New Verilog File (continued) Incremental route with NanoRoute/WRoute Antenna diodes are disabled because poly/diffusion cannot be modified. Routers automatically detect opens and shorts, and incrementally route
any nets that are incomplete or have violations. The old Verilog netlist after ECO might be slightly different from the
new Verilog netlist. The auto-generated ports and nets probably have different names.
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Postmask ECO with a New Verilog File Example Tcl Script # Read old Verilog netlist into Encounter
loadConfig oldchip.conf # Read old floorplan, special routes, placements and routing
defIn oldchip.def # Compare the current old netlist to the new Verilog netlist
ecoCompareNetlist -verilog new.v -outFile oldchip.eco # Load the ECO file to incrementally update the current netlist to match the new netlist
loadECO -useSpareCells -suffix _SPARE oldchip.eco # Write out changed Verilog netlist if desired
saveNetlist oldchip_after_eco.v # Incremental route
setNanoRouteMode routeInsertAntennaDiode false globalDetailRoute
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Comparing Netlists The following command compares the currently loaded netlist with a
different netlist file: ecoCompareNetlist {-verilog | -def } -outFile The ecoCompareNetlist command uses instance names and net names
for matching. An ECO file (file.eco), or change list, is generated. The file has all the changes needed to differentiate the current netlist from
the external netlist. The file.eco contains the loadECO syntax.
The Verilog file must already be uniquified.
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The loadECO Command and Spare Cell Support You can use the following command to support spare cells in the design: loadECO[-useSpareCells | -useGACells ] [-suffix ]
-useSpareCells
For a newly added instance, spare cells are chosen by looking for a spare cell that matches the new cell type and is closest to the pins connected to the new instance. When an instance is deleted, it is really renamed as a spare cell i1/i2/i3 becomes i1/i2/i3_SPARE If a net is deleted, any routing attached is deleted If a net is modified, any routing attached is not affected
-suffix
Suffix to append to new spare cells, default “_SPARE”
-useGACells
Same as –useSpareCells except for GACoreSite type cells. New GACoreSite type cells are left unplaced. Deleted GACoreSite cells are really deleted.
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Blackbox What-If Timing Analysis
Appendix A
March 3, 2004
What-If Timing Analysis What-If Timing Analysis: The capability allowing on-the-fly modifications of blackbox timing arcs along with subsequent STA.
The design cycle can start: Without blackbox timing models With preliminary blackbox timing models (soft IPs)
You can use What-If commands for a powerful and interactive budgeting at the top level of the design.
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Timing Model Normalized 5
4
6
5
4
6
1
2 7
#
3
Data Type
Command
1
Combinational delay from an input port to an output port, setBlackBoxCombDelay including the driver delay
2
Timing check, delay from the clock input port to the data input setBlackBoxTimingCheck port
3
Sequential delay from the clock input port to the data output port, including driver delay
setBlackBoxSeqDelay
4
Driver type Driver input slew Total driver output net capacitance (optional)
setBlackBoxDriveType
Clock insertion delay to internal registers
setBlackBoxClockLatency
5 6 7
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What-If Graphical User Interface
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Application Examples Top-Down Flow You can define a preliminary timing model and the constraints of a
blackbox in its environment at the top level. You can refine timing models and constraints of soft IPs, taking into
account a new top-level design environment. Starting Block Implementation Before Top STA After importing the netlist of a blackbox, you can refine its timing
budget. Run a top-level STA using a timing model from block synthesis. Then,
check the model and generate a new set of SDC constraints if needed.
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SoC Encounter Support for TSMC Reference Flow
Appendix B
March 3, 2004
Crosstalk Prevention Using Encounter Placement and optimization stage Set max transition to prevent weak victims. Avoid the strong aggressors created by sharp transition.
Postplacement stage First Encounter: slew balance and congestion removal
Routing stage NanoRoute: global routing, track assignment, and detail routing with
crosstalk prevention Prevention effects Routing is more effective than placement in crosstalk prevention. Target for reducing crosstalk violations is 50% or more per iteration.
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Crosstalk Repair Using Encounter CeltIC — First Encounter — NanoRoute — CeltIC loops NanoRoute fixes glitch violations. First Encounter fixes timing violation.
Most crosstalk glitches and timing violations are fixed in 3 iterations. Manual script is used to fix remaining violations. High-strength victim nets Wire spacing Buffer insertion
Low-strength victim nets Cells are sized up.
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Encounter Supports Design for Manufacturability in Reference Flow Design for manufacturability (DFM) provides increased visibility into the manufacturing process. DFM addresses nanometer challenges, including: Uniform density and thickness Via placement Signal electromigration Dynamic IR drop LEF spacing and blockage modeling enhancements Routing rule support in NanoRoute tool Reliability enhancements (such as double cut vias)
DFM is incorporated through design rules, tech files, and scripts.
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Redundant Via Insertion Methodology For Yield Improvement, NanoRoute supports redundant via insertion for TSMC 130 nm and 90 nm technologies.
0.08 µ 0.05 µ
(f)
(d)
(a)
(b)
0.05 µ 0.05 µ
0.08 µ
0.005 µ
0.005 µ 0.05 µ
0.005 µ
0.005 µ
(a)
(c)
(b)
(c) 0.08 µ
0.05 µ
0.05 µ 0.08 µ
0.005 µ 0.005 µ
0.005 µ
(d)
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(f)
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®
Partitioning
Appendix C
March 3, 2004
Partition Menu Design
Partition
FloorPlan
Place
Specify Partition... Specify Black Box Create Feedthroughs… Assign Black Box Pins Show Wire Crossing Estimate Routing Channel… Partition… Unpartition… Check Pin Assignment Change Partition View
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Clock
Route …
Creates the partitions. Displays Trial Route feedthrough wires that are crossing over a selected partition. Flattens the partition. Changes design view between chip level and partitions.
126
Blackbox Options A blackbox is a special application of the partition. Create a LEF file for the hierarchical instance (module, submodule, or block)
and enter the file name in the Design Import form. After importing the design, dark blue colored blackbox guides appear with the
blocks. Complete floorplanning with the blackbox. Use the command, specifyBlackBox . Use the Specify Partition form for blackboxes as well as for partitions. You can resize the blackbox. Apply the resizeBlackBox command. Run placement and Trial Route. Generate blackbox pins by applying the blackBoxPinAssign command. The Save Partition form will also create a blackbox subdirectory.
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Blackbox Pin Assignment Before Black Box Pin Assign
You need to update the Blackbox abstract file with the pin placements.
After Black Box Pin Assign
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Specifying a Blackbox Partition – Specify Black Box
The following text commands provide equivalent or additional functionality: resizeBlackBox specifyBlackBox unspecifyBlackBox 3/3/04
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Partitioning a Design Divides the design task into manageable partitions so that work can
continue on several blocks in parallel. Partitioning uses the full-chip environment and performs analysis to Analyze top-level route congesting from early top-level floorplanning
information. Optimize pin assignment based on full-chip placed and routed (in-context)
results. Push down the top-level floorplan objects (power plan, blockages) into
each partition if they overlap the partition. Generate timing budgets based on full-chip timing analysis.
Timing constraints, clock exceptions, and path exceptions are pushed down to all partitions. Stamp models are generated for the partitions.
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Results of Partitioning Results of partitioning are two levels of partition hierarchy — the top-level infrastructure and the partition level. Partitioning generates top-level partitions and pushes down floorplan
objects to the floorplan file. Partitioning generates all the necessary files for the First Encounter
engine and other backend tools. You create partitions that exist: Logically
A partition is one of the modules or submodules in the design. Physically
A partition must be completely intact and constrained by a fence.
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Steps in Partitioning a Design Specifying the Partitions The name of the module that you want partitioned.
Partition – Specify Partition Directory where the files that belong to the partition will be saved.
Layer names are determined from the technology file. The LEF file for the partition will contain obstructions for the unselected layers.
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Steps in Partitioning a Design (continued) Specifying Partition Pins Partition Pins
Core of Partition
Std Cell Row
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Min Pin spacing on all sides
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Steps in Partitioning a Design (continued) Partitioning the Partitions Partition – Partition
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Steps in Partitioning a Design (continued) Saving the Partition – Creates the infrastructure for the hierarchy. Design – Save Partition
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Specifying a Module to Be a Partition Specifying the Partitions Each specified module must first be floorplanned. For multiple instantiated modules to be partitioned you need to
uniquify the netlist in the synthesis step of the design process. You can change the standard cell row height and place the partition’s
pin away from standard cell power rails.
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Multiply Instantiated Partitions Handling Repeated Partitions These are multiple instantiated hierarchical instance of same cell type. You can choose all or none of them are to be partitions. You can choose to modify the netlist, so hierarchical instance names
are unique. The hierarchical instance entered in the Specify Partition form is the
master partition and other partitions are clones of it. Clones can have orientation changed using their Attribute form during
floorplanning.
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Running the Unpartition Program Use the Unpartition program to remove selected partitions from a design. If changes are necessary for any of the partitions, you can change the partition status from a block to a fence. Choose Partition – Unpartition.
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Deriving Timing Budget Files for Partitions Partition – Partition
The Trial IPO Estimates option produces proper timing constraints between partitions.
To resolve multiple timing constraints for I/O partitioning
Proportional will create proportional timing constraints between partitions.
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Timing Budgeting Each block requires: Block 1
Clock definition set_input_delay
L
Block 2
set_output_delay
L
set_drive set_load
L
Path exceptions (False, multicycle paths)
Block 3
Accurate timing budgets result in predictable timing convergence. 3/3/04
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Deriving Timing Budget Files for Partitions (continued) Produces proper timing constraints between partitions. Resolves conflict for multiple timing constraints for partition I/Os. Makes the timing constraints proportional between top and partitions or can fix
the top first.
After Saving Partition Top Level Files top.v top.conf top.fp top.fp.spr top.lef top.constr top.dat top.def top.lib top.tlf top.pwr.cmd
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Partition Files
Files for FEU
par_1.v par_1.conf par_1.fp par_1.fp.spr par_1.constr par_1.constr.pks par_1.constr.pt
Files for FEU and third party tools
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par_1.trk.tcl par_1.def par_1.pdef par_1.fp.cmd par_1.pwr.cmd par_1.pin.tdf 141
Timing Budget – Interface Logic Models Interface logic models (ILMs) provide an accurate, yet simplified timing models
for hierarchical design. The original gate-level netlist of a block is modeled by another gate-level netlist
that contains the interface logic of the block. The logic other than the interface logic is stripped out, thus simplifying the
number of computations and shortening the time taken to perform timing analysis.
A
B
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X
A
X
B
Y
Y
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Partitioning ILMs Bottom-Up Flow Use the interface logic model (ILM) flow to produce accurate timing analysis for a completed partition design. To prepare for an ILM flow: 1. Make sure the work directories are created by a partition flow (saving partition). 2. When the design work is complete for all partitions, use the two commands to derive and save the ILM netlist and SPEF files for each partition. deriveInterfaceLogic saveInterfaceLogic -spef 3. To do timing analysis for the entire chip, cd to the top-level directory where the work is complete.
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Partitioning ILMs Bottom-Up Flow Top Level Note When restoring the design, you need to stitch the SPEF file for each partition by using the spefIn command.
(continued)
Completed chip netlist
Design Import with partition ILM files Load top -level floorplan Load partition SPEF files by:
spefIn -ilm
With ILM files from Step 2, the First Encounter tool is now in an ILM mode.
for all partitions
Run Placement and Trial Route Flatten ILMs When the timing graph is built, the SPEF data for the partitions are stitched and the SPEF for the top level are automatically extracted and stitched.
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Extract RC Timing Analysis and Optimization
Trial Route knows to route to the partition pin locations.
Un-Flatten ILMs Top-Level CTS and Detail Route Save Design SoC Encounter
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Partition Floorplan Objects Partition Pin Blockage — to block area from creating pins on specific metal layers. Select the metal layers to be blocked. Partition Feedthrough — to assign routing feed through area on a specific metal layers. Feedthrough object must cut through both sides of the partition. Add Partition Pin Guide — to assign guides where you want to place certain pins on the partition.
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Partition Floorplan Object — Partition Feedthrough You can use Partition Feedthrough to reserve space in a partition for toplevel routing and buffer insertion. This flow is to: Create partitions. Create partition feedthroughs. Commit partitions.
Partition feedthrough affects only the physical aspect of the partition not the logical aspect. The two types of partition feedthrough are: Channel — For top-level routing Placement island — For top-level buffer insertion
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Partition Floorplan Object – Partition Feedthrough (continued) Method 1: Use the Add Partition
Feedthrough icon to create the feedthrough buffer on the partition. Double-click the buffer to open the Object Attribute form, specify the metal layer, and click OK.
Partition Feedthrough Floorplan icon
Use Partition – Create Feedthrough
This creates the channel for the routing on the specified layers at the top level and pushes down appropriate routing blockages at the block level. Method 2: To specify narrow
feedthroughs or several of them on a given partition, choose Partition – Create Feedthrough to open the Create Feedthrough form.
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Partition Feedthrough – Placement Island At partition level, commit partition automatically creates the following: Routing blockage(s) for channel feedthrough Placement blockage for placement island feedthrough
Channel Feedthrough (layer = M6)
Routing Obstruction (M6)
Channel Feedthrough (layer = M5)
Placement Obstruction
Placement Island Feedthrough
Partition with Partition Feedthroughs
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Routing Obstruction (M5)
Committed Partition
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Finding Feedthrough Nets Use the showPtnWireX command to find nets that cross partitions. showPtnWireX [ptnName] [–outfile ] [-exclude Net ]
Use ptnName to generate a file that lists the nets that cross a
specific partition. Use the output file as a starting point to generate a list of nets for feedthrough insertion. Not all nets in the generated partition-crossing net file will become
feedthrough nets automatically. You need to decide which nets to use for inserting feedthrough buffer
cells and add them to the excluded nets file.
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Partition Feedthrough Buffer Insertion Use insertPtnFeedthrough for inserting partition feedthrough buffer cells insertPtnFeedthrough –bufCell -selectNet | { -chanLess [-excludeNet ] } {-doubleBuffer | -nobuffer} [-netMapping]
The -chanLess option specifies that the design is pure channelless, having no channel available for routing, and therefore all nets must be selected for feedthrough insertion.
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Partition Feedthrough Buffer Cell (Continued) Use netMapping to generate a mapping file for the original and new created net names. Use doubleBuffer to insert 2 buffers for feedthrough nets. Insert one buffer close to incoming pin and another one close to an
outgoing pin. Without this option, the buffer is inserted near the incoming pin.
Technique Create new feedthrough pins. Insert buffers and modify netlist. Run ecoPlace to place inserted buffers.
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Partition Feedthrough Without Buffer Insertion Allow creating logical partition feedthrough without inserting any buffer Use the insertPtnfeedthrough –noBuffer option. Adds a Verilog assign statement in the netlist of the partition block.
FE_FEEDX_new_in_port
FE_FEEDX_new_out_port
assign FE_FEEDX_new_in_port
=
FE_FEEDX_new_out_port
;
Note: A dummy buffer with FE_DUMMYCELL cell type is inserted inside the data base to represent an assign statement. 3/3/04
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Partition Floorplan Objects: Partition Pin Guide Partition Pin Guide — to create partition port for a net or a bus name. Must overlap partition fence. 1
2 3
Partition1
Partition2
1. You can create ports at the top side, starting left to right. 2. You can create ports at the top and bottom sides of Partition1 (one set of pins will be actually feed-through pins), and create ports at the top side of Partition2, starting left-toright. 3. You can create ports at the right side, starting bottom-to-top, of Partition1.
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Partition Floorplan Objects: Partition Pin Guide (continued) Assign net names by changing the
partition pin guide’s Name to a net name, bus name (bus_name[#,#]), or net group name. For a net group, use these
commands: createNetGroup and addNetToNetGroup. Assign port names by changing the partition pin guide’s name to a port name or pin group name. For a pin group, use these
commands: createCellPinGroup and addPinToCellPinGroup. Then, enter cell type name in the
PinGroup Cell field. 3/3/04
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Partition Pin Editor Use the interactive pin editor to edit pin properties: Location Metal layer Pin depth and width Equal spacing Snapping to metal tracks or Microns. Fixing
Choose Tools – Pin Editor.
Can list pins as: All Side Unassigned Other (group)
Group pins as a bus.
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Channel Width Estimation After specifying the partition, you
can estimate the required spacing between partitions, blackboxes, and hard macros, and update the floorplan based on the required spacing information.
To estimate the routing channel, choose Partition – Estimate Routing Channel.
To estimate the routing channel, use this form: This will output an estimate of the
required spacing surrounding each partition based on its pins, the relative distance between partition blocks required for toplevel routing. This output also includes the estimated distance between blocks and core boundaries (top, bottom, left, right). 3/3/04
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Example Report of Channel Width Estimation Instance name Block1
HB1
BB1
bot-boundary bot-boundary bot-boundary lft-boundary lft-boundary lft-boundary INST1 INST1 HB1 HB1 INST4 INST4 … …
INST4
INST3 INST2 INST1
Partition
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HB2
Hard macro
Blackbox
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Block2
Spacing in micron Current
INST1 24.6 INST2 54.3 HB2 25.0 INST1 38.2 INST3 43.2 HB1 46.8 INST3 64.8 INST2 72.1 top-boundary 57.2 BB1 44.5 top-boundary 59.5 rht-boundary 53.0 … … … …
Required 28.8 46.9 31.2 45.5 37.8 33.5 39.4 55.7 10.9 69.1 51.7 50.5 … …
Core boundary edge
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Channel Width Estimation Constraints Set the following block placer constraints when adjusting channel widths Block halo Block-to-block distance (setBlockDistance) Block-to-boundary distance (setBlockToBoundary) Block order and alignment (setBlockOrderAlignment) Net weight (specifyNetWeight)
Reshape blackboxes and partitions to improve congestion The Channel Width Estimator honors user-specified block aspect ratio
constraint (setBlockAspectRatio).
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Global Partition Pin Size You can define the global pin size constraint for a specific partition. Set the global pin width, the pin depth, or both.
Applies to all pins of a partition that do not have their own pin widths/depths. Use the setPtnPinWidth and setPtnPinDepth Tcl commands to set global pin width and depth, respectively. setPtnPinWidth setPtnPinDepth Width (in micron) Depth Width Depth 3/3/04
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Channelless Partitions Different types of hierarchical design methodology: Channel-based (All top-level routing use channels.) Channelless (All top-level routing use feedthroughs.) Mixed (Some top-level routing use channels; some use feedthroughs.)
Channel-based methodology
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Channelless methodology
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Channelless Partitions (continued) Techniques and approaches to insert feedthroughs Use insertPtnFeedthrough command. Changes the top-level and partition-level netlists.
Use Partition – Create Feedthrough to create feedthroughs No netlist change
insertPtnFeedthrough is recommended for pure channelless or mixed methodology.
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Channelless Partitions Simple Methodology Flow Design import Floorplan a design Specify partitions Place (with Amoeba) trialRoute showPtnWireX insertPtnFeedthrough trialRoute extractRc buildTimingGraph Commit partition Save partition 3/3/04
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Channelless Partitions Simple Methodology Flow
(continued)
showPtnWireX generates an output file that lists all nets routed over partitions. You have a choice of inserting feedthroughs for all nets or only for selected nets. insertPtnFeedthrough can read a file that lists all the top-level nets for feedthrough insertion. This command does the following: Inserts buffer or buffers for the feedthrough nets. Modifies the netlist. Places buffers in the appropriate locations. Generates a partition boundary. Creates a timing budget with feedthroughs.
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Channelless Partitions Example of Channelless Methodology Design After Committing Partitions
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®
Flip-Chip
Appendix D
March 3, 2004
Flip-Chip Functions Supports full flip-chip flow. Creates bump MATRIX. Creates rows for I/O placement. Runs automatic I/O placement. Runs signal routing from bumps to I/O. Runs power routing from bumps to stripes. Supports flat and hierarchical flows. Chip bumps Contact pads
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Area I/O Features Bump and tile flows Tile selection Bump array and matrix generation Bump assignment (signal and power/ground) I/O row generation Interface to CIOP (route feasibility)
AIO placement Routing SRoute power and signal bumps Differential routing
Hierarchical flow – partition LEF syntax
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Area I/O Flows Verilog
I/O file (Bump/Rows)
LEF
Floorplan
Bump Flow
Edit Bumps Route Feasibility Interface Add Stripes
CIOP Route Feasibility
Place AIO Assign Bumps Route Bumps
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Partition
PlaceCells
Block Design
RouteDesign
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Flip Chip: Add Tile Icon Placing Tiles Tiles are a group of bumps. Tiles can contain macros
and routing.
Add Tile Icon
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Flip-Chip and Chip I/O Setup Create bump array (4x4) to match package balls.
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Flip-Chip: Signal Assignment
Select an I/O signal.
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Flip-Chip: Signal Assignment (continued)
Signal Bumps Blue = signal assigned
CLK
DI[0]
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Flip-Chip: Power/Ground Assignment Select Bumps and assign power Red = power
Select Bumps and assign ground Yellow = ground
Signal Bumps Blue = signal
Signal
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Power
Ground
Signal
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Flip-Chip: I/O Driver Row Place rows for I/O driver cells. These areas are used by placeAIO.
I/O Row
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Flip-Chip: Route Feasibility Inputs Aio_bga.cio # package binary Default.ldf
# Lef/cml pointer
Outputs route_feasibility.cio
# binary
route_feasibility.rpt
# report
Highlight un-routable Bumps
CIOP package routing
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Place: PlaceAIO placeAIO places I/O driver in rows. LEF OBS LAYER OVERLAP Restricts standard cell
placement. Overlap
IO Driver
Bump
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Partition – Internal Pin for Better Routing Bump is pushed into Blk2 Blk1
Blk2
Routing without internal pin
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Routing with internal pin
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Partition Commands Move module inside floorplan view Double click on partition (attribute editor) – change size placeAIO and trialRoute Specify partition handlePtnAreaIo
# New TCL command
commitPartition checkPinAssignment Change partition view
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Partition – FeedThru Buffer Partition
IO Cell
Bump input IO output (internal pin) Inserted buffer Boundary Pin Partition Standard cell
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IO Driver output Buffer
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Partition – Commit
Partition
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Placement Island
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Partition – Block: Push Down Blockages
Cell already in module
Bump Routing Blockage
P&R Blockages
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LEF 5.5 Syntax BUMP MACRO bumpcell CLASS COVER BUMP ; Pin PAD ;
# no SITE required. Only one pin is allowed
Driver Cell MACRO drivercell CLASS PAD AREAIO ; SITE IO ; PIN IN ; LEF Tile Macro
# multiple pins – must be flattened
MACRO Tile1 CLASS COVER BUMP ; * “BUMP” is a reserved word in LEF5.5 3/3/04
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Flip-Chip Routing Support Supports both signal and power bump
routing. fcroute is the new command that supports
this feature. Routes signal bump cells to the I/O cell. Routes power bump cells to the nearby
stripes. Routes bump pins in the cover macro to the
I/O drivers for the signals. Routes power bumps in the cover macro to
the stripe rails.
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Flip-Chip Routing Support (continued) Signal Routing Primary and secondary layer change
control. An option to use the user-defined
width to do the bump to IO driver connection. Supports Redistribution Layer (RDL)
Routing. An RDL is a routing layer of conductive metal within an IC that connects the diepad or solder bump to a connection point on an I/O driver. The Encounter router supports routing to this special layer.
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