Intel® Quartus® Prime Pro Edition User Guide: Timing Analyzer

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ID 683243
Date 10/04/2021
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Document Table of Contents
Document Table of Contents x
1. Timing Analysis Introduction 2. Using the Intel® Quartus® Prime Timing Analyzer A. Intel® Quartus® Prime Pro Edition User Guides
1. Timing Analysis Introduction x
1.1. Timing Analysis Basic Concepts 1.2. Timing Analysis Overview Document Revision History
1.1. Timing Analysis Basic Concepts x
1.1.1. Timing Path and Clock Analysis 1.1.2. Clock Setup Analysis 1.1.3. Clock Hold Analysis 1.1.4. Recovery and Removal Analysis 1.1.5. Multicycle Path Analysis 1.1.6. Metastability Analysis 1.1.7. Timing Pessimism 1.1.8. Clock-As-Data Analysis 1.1.9. Multicorner Timing Analysis 1.1.10. Time Borrowing
1.1.1. Timing Path and Clock Analysis x
1.1.1.1. The Timing Netlist 1.1.1.2. Timing Paths 1.1.1.3. Data and Clock Arrival Times 1.1.1.4. Launch and Latch Edges
1.1.5. Multicycle Path Analysis x
1.1.5.1. Multicycle Clock Hold 1.1.5.2. Multicycle Clock Setup
1.1.10. Time Borrowing x
1.1.10.1. Time Borrowing Limitations 1.1.10.2. Time Borrowing with Latches
2. Using the Intel® Quartus® Prime Timing Analyzer x
2.1. Timing Analysis Flow 2.2. Step 1: Specify Timing Analyzer Settings 2.3. Step 2: Specify Timing Constraints 2.4. Step 3: Run the Timing Analyzer 2.5. Step 4: Analyze Timing Reports 2.6. Applying Timing Constraints 2.7. Timing Analyzer Tcl Commands 2.8. Timing Analysis of Imported Compilation Results 2.9. Using the Intel® Quartus® Prime Timing Analyzer Document Revision History 2.10. Intel® Quartus® Prime Pro Edition User Guide: Timing Analyzer Archive
2.4. Step 3: Run the Timing Analyzer x
2.4.1. Setting the Operating Conditions 2.4.2. Enabling Time Borrowing Optimization
2.5. Step 4: Analyze Timing Reports x
2.5.1. Generating Timing Reports 2.5.2. Cross-Probing with Design Assistant 2.5.3. Launching Design Assistant from Timing Analyzer 2.5.4. Locating Timing Paths in Other Tools 2.5.5. Correlating Constraints to the Timing Report
2.5.1. Generating Timing Reports x
2.5.1.1. Report Fmax Summary 2.5.1.2. Report Timing 2.5.1.3. Report Data Delay 2.5.1.4. Report Clocks and Clock Networks 2.5.1.5. Report Clock Transfers 2.5.1.6. Report Logic Depth 2.5.1.7. Report Neighbor Paths 2.5.1.8. Report Register Spread 2.5.1.9. Report Route Net of Interest 2.5.1.10. Report Retiming Restrictions 2.5.1.11. Report Reset Statistics 2.5.1.12. Report Pipelining Information 2.5.1.13. Report Asynchronous CDC 2.5.1.14. Report CDC Viewer 2.5.1.15. Report Time Borrowing Data 2.5.1.16. Report Exceptions and Exceptions Reachability
2.5.1.8. Report Register Spread x
2.5.1.8.1. Registers with High Timing Path Endpoint Tension 2.5.1.8.2. Registers with High Immediate Fan-Out Tension
2.5.2. Cross-Probing with Design Assistant x
2.5.2.1. Cross-Probing from Design Assistant to Timing Analyzer
2.6. Applying Timing Constraints x
2.6.1. Recommended Initial SDC Constraints 2.6.2. SDC File Precedence 2.6.3. Modifying Iterative Constraints 2.6.4. Using Entity-bound SDC Files 2.6.5. Creating Clocks and Clock Constraints 2.6.6. Creating I/O Constraints 2.6.7. Creating Delay and Skew Constraints 2.6.8. Creating Timing Exceptions 2.6.9. Using Fitter Overconstraints 2.6.10. Example Circuit and SDC File
2.6.1. Recommended Initial SDC Constraints x
2.6.1.1. Create Clock (create_clock) 2.6.1.2. Derive PLL Clocks (derive_pll_clocks) 2.6.1.3. Derive Clock Uncertainty (derive_clock_uncertainty) 2.6.1.4. Set Clock Groups (set_clock_groups)
2.6.4. Using Entity-bound SDC Files x
2.6.4.1. Entity-bound Constraint Scope 2.6.4.2. Entity-bound Constraint Examples
2.6.5. Creating Clocks and Clock Constraints x
2.6.5.1. Creating Base Clocks 2.6.5.2. Creating Virtual Clocks 2.6.5.3. Creating Generated Clocks (create_generated_clock) 2.6.5.4. Deriving PLL Clocks 2.6.5.5. Creating Clock Groups (set_clock_groups) 2.6.5.6. Accounting for Clock Effect Characteristics 2.6.5.7. Constraining CDC Paths
2.6.5.1. Creating Base Clocks x
2.6.5.1.1. Automatic Clock Detection and Constraint Creation
2.6.5.2. Creating Virtual Clocks x
2.6.5.2.1. Specifying I/O Interface Uncertainty 2.6.5.2.2. I/O Interface Clock Uncertainty Example
2.6.5.3. Creating Generated Clocks (create_generated_clock) x
2.6.5.3.1. Clock Divider Example (-divide_by) 2.6.5.3.2. Clock Multiplexer Example
2.6.5.5. Creating Clock Groups (set_clock_groups) x
2.6.5.5.1. Exclusive Clock Groups (-logically_exclusive or -physically_exclusive) 2.6.5.5.2. Asynchronous Clock Groups (-asynchronous) 2.6.5.5.3. set_clock_groups Constraint Tips
2.6.5.6. Accounting for Clock Effect Characteristics x
2.6.5.6.1. Set Clock Latency (set_clock_latency) 2.6.5.6.2. Clock Uncertainty
2.6.6. Creating I/O Constraints x
2.6.6.1. Input Constraints (set_input_delay) 2.6.6.2. Output Constraints (set_output_delay)
2.6.7. Creating Delay and Skew Constraints x
2.6.7.1. Advanced I/O Timing and Board Trace Model Delay 2.6.7.2. Maximum Skew (set_max_skew) 2.6.7.3. Net Delay (set_net_delay)
2.6.8. Creating Timing Exceptions x
2.6.8.1. Timing Exception Precedence 2.6.8.2. False Paths (set_false_path) 2.6.8.3. Minimum and Maximum Delays 2.6.8.4. Multicycle Paths 2.6.8.5. Multicycle Exception Examples 2.6.8.6. Delay Annotation 2.6.8.7. Constraining Design Partition Ports
2.6.8.4. Multicycle Paths x
2.6.8.4.1. Common Multicycle Applications 2.6.8.4.2. Relaxing Setup with Multicycle (set_multicyle_path) 2.6.8.4.3. Accounting for a Phase Shift (-phase)
2.6.8.5. Multicycle Exception Examples x
2.6.8.5.1. Default Multicycle Analysis 2.6.8.5.2. End Multicycle Setup = 2 and End Multicycle Hold = 0 2.6.8.5.3. End Multicycle Setup = 2 and End Multicycle Hold = 1 2.6.8.5.4. Same Frequency Clocks with Destination Clock Offset 2.6.8.5.5. Destination Clock Frequency is a Multiple of the Source Clock Frequency 2.6.8.5.6. Destination Clock Frequency is a Multiple of the Source Clock Frequency with an Offset 2.6.8.5.7. Source Clock Frequency is a Multiple of the Destination Clock Frequency 2.6.8.5.8. Source Clock Frequency is a Multiple of the Destination Clock Frequency with an Offset
2.7. Timing Analyzer Tcl Commands x
2.7.1. The quartus_sta Executable 2.7.2. Collection Commands
2.7.2. Collection Commands x
2.7.2.1. Wildcard Characters 2.7.2.2. Adding and Removing Collection Items 2.7.2.3. Query of Collections 2.7.2.4. Using the get_pins Command
1. Timing Analysis Introduction
2. Using the Intel® Quartus® Prime Timing Analyzer
A. Intel® Quartus® Prime Pro Edition User Guides

1.1.8. Clock-As-Data Analysis

The majority of FPGA designs contain simple connections between any two nodes known as either a data path or a clock path.

A data path is a connection between the output of a synchronous element to the input of another synchronous element.

A clock is a connection to the clock pin of a synchronous element. However, for more complex FPGA designs, such as designs that use source-synchronous interfaces, this simplified view is no longer sufficient. Clock-as-data analysis is performed in circuits with elements such as clock dividers and DDR source-synchronous outputs.

The connection between the input clock port and output clock port can be treated either as a clock path or a data path. Figure 32 shows a design where the path from port clk_in to port clk_out is both a clock and a data path. The clock path is from the port clk_in to the register reg_data clock pin. The data path is from port clk_in to the port clk_out.

Figure 32. Simplified Source Synchronous Output

With clock-as-data analysis, the Timing Analyzer provides a more accurate analysis of the path based on user constraints. For the clock path analysis, any phase shift associated with the phase-locked loop (PLL) is taken into consideration. For the data path analysis, any phase shift associated with the PLL is taken into consideration rather than ignored.

The clock-as-data analysis also applies to internally generated clock dividers. In the following figure, the waveforms are for the inverter feedback path, analyzed during timing analysis. The output of the divider register determines the launch time, and the clock port of the register determines the latch time.

Figure 33. Clock Divider
Level Two Title