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

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ID 683243
Date 1/31/2023
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Document Table of Contents
Document Table of Contents x
1. Answers to Top FAQs 2. Timing Analysis Introduction 3. Using the Intel® Quartus® Prime Timing Analyzer A. Intel® Quartus® Prime Pro Edition User Guides
2. Timing Analysis Introduction x
2.1. What's New In This Version 2.2. Timing Analysis Basic Concepts 2.3. Timing Analysis Overview Document Revision History
2.2. Timing Analysis Basic Concepts x
2.2.1. Timing Path and Clock Analysis 2.2.2. Clock Setup Analysis 2.2.3. Clock Hold Analysis 2.2.4. Recovery and Removal Analysis 2.2.5. Multicycle Path Analysis 2.2.6. Metastability Analysis 2.2.7. Timing Pessimism 2.2.8. Clock-As-Data Analysis 2.2.9. Multicorner Timing Analysis 2.2.10. Time Borrowing
2.2.1. Timing Path and Clock Analysis x
2.2.1.1. The Timing Netlist 2.2.1.2. Timing Paths 2.2.1.3. Data and Clock Arrival Times 2.2.1.4. Launch and Latch Edges
2.2.5. Multicycle Path Analysis x
2.2.5.1. Multicycle Clock Hold 2.2.5.2. Multicycle Clock Setup
2.2.10. Time Borrowing x
2.2.10.1. Time Borrowing Limitations 2.2.10.2. Time Borrowing with Latches
3. Using the Intel® Quartus® Prime Timing Analyzer x
3.1. Timing Analysis Flow 3.2. Step 1: Specify Timing Analyzer Settings 3.3. Step 2: Specify Timing Constraints 3.4. Step 3: Run the Timing Analyzer 3.5. Step 4: Analyze Timing Reports 3.6. Applying Timing Constraints 3.7. Timing Analyzer Tcl Commands 3.8. Timing Analysis of Imported Compilation Results 3.9. Using the Intel® Quartus® Prime Timing Analyzer Document Revision History 3.10. Intel® Quartus® Prime Pro Edition User Guide: Timing Analyzer Archive
3.4. Step 3: Run the Timing Analyzer x
3.4.1. Setting the Operating Conditions for Timing Analysis 3.4.2. Enabling Time Borrowing Optimization
3.5. Step 4: Analyze Timing Reports x
3.5.1. Generating Timing Reports 3.5.2. Cross-Probing with Design Assistant 3.5.3. Launching Design Assistant from Timing Analyzer 3.5.4. Locating Timing Paths in Other Tools 3.5.5. Correlating Constraints to the Timing Report
3.5.1. Generating Timing Reports x
3.5.1.1. Report Fmax Summary 3.5.1.2. Report Timing 3.5.1.3. Report Timing By Source Files 3.5.1.4. Report Data Delay 3.5.1.5. Report Net Delay 3.5.1.6. Report Clocks and Clock Network 3.5.1.7. Report Clock Transfers 3.5.1.8. Report Metastability 3.5.1.9. Report CDC Viewer 3.5.1.10. Report Asynchronous CDC 3.5.1.11. Report Logic Depth 3.5.1.12. Report Neighbor Paths 3.5.1.13. Report Register Spread 3.5.1.14. Report Route Net of Interest 3.5.1.15. Report Retiming Restrictions 3.5.1.16. Report Register Statistics 3.5.1.17. Report Pipelining Information 3.5.1.18. Report Time Borrowing Data 3.5.1.19. Report Exceptions and Exceptions Reachability 3.5.1.20. Report Bottlenecks
3.5.1.13. Report Register Spread x
3.5.1.13.1. Registers with High Timing Path Endpoint Tension 3.5.1.13.2. Registers with High Immediate Fan-Out Tension
3.5.1.20. Report Bottlenecks x
3.5.1.20.1. Specifying Custom Bottleneck Criteria
3.5.2. Cross-Probing with Design Assistant x
3.5.2.1. Cross-Probing from Design Assistant to Timing Analyzer
3.6. Applying Timing Constraints x
3.6.1. Recommended Initial SDC Constraints 3.6.2. SDC File Precedence 3.6.3. Modifying Iterative Constraints 3.6.4. Using Entity-bound SDC Files 3.6.5. Creating Clocks and Clock Constraints 3.6.6. Creating I/O Constraints 3.6.7. Creating Delay and Skew Constraints 3.6.8. Creating Timing Exceptions 3.6.9. Using Fitter Overconstraints 3.6.10. Example Circuit and SDC File
3.6.1. Recommended Initial SDC Constraints x
3.6.1.1. Create Clock (create_clock) 3.6.1.2. Derive PLL Clocks (derive_pll_clocks) 3.6.1.3. Derive Clock Uncertainty (derive_clock_uncertainty) 3.6.1.4. Set Clock Groups (set_clock_groups)
3.6.4. Using Entity-bound SDC Files x
3.6.4.1. Entity-bound Constraint Scope 3.6.4.2. Entity-bound Constraint Examples
3.6.5. Creating Clocks and Clock Constraints x
3.6.5.1. Creating Base Clocks 3.6.5.2. Creating Virtual Clocks 3.6.5.3. Creating Generated Clocks (create_generated_clock) 3.6.5.4. Deriving PLL Clocks 3.6.5.5. Creating Clock Groups (set_clock_groups) 3.6.5.6. Accounting for Clock Effect Characteristics 3.6.5.7. Constraining CDC Paths
3.6.5.1. Creating Base Clocks x
3.6.5.1.1. Automatic Clock Detection and Constraint Creation
3.6.5.2. Creating Virtual Clocks x
3.6.5.2.1. Specifying I/O Interface Uncertainty 3.6.5.2.2. I/O Interface Clock Uncertainty Example
3.6.5.3. Creating Generated Clocks (create_generated_clock) x
3.6.5.3.1. Clock Divider Example (-divide_by) 3.6.5.3.2. Clock Multiplexer Example
3.6.5.5. Creating Clock Groups (set_clock_groups) x
3.6.5.5.1. Exclusive Clock Groups (-logically_exclusive or -physically_exclusive) 3.6.5.5.2. Asynchronous Clock Groups (-asynchronous) 3.6.5.5.3. set_clock_groups Constraint Tips
3.6.5.6. Accounting for Clock Effect Characteristics x
3.6.5.6.1. Set Clock Latency (set_clock_latency) 3.6.5.6.2. Clock Uncertainty
3.6.6. Creating I/O Constraints x
3.6.6.1. Input Constraints (set_input_delay) 3.6.6.2. Output Constraints (set_output_delay)
3.6.7. Creating Delay and Skew Constraints x
3.6.7.1. Advanced I/O Timing and Board Trace Model Delay 3.6.7.2. Maximum Skew (set_max_skew) 3.6.7.3. Net Delay (set_net_delay)
3.6.8. Creating Timing Exceptions x
3.6.8.1. Timing Exception Precedence 3.6.8.2. False Paths (set_false_path) 3.6.8.3. Minimum and Maximum Delays 3.6.8.4. Multicycle Paths 3.6.8.5. Multicycle Exception Examples 3.6.8.6. Delay Annotation 3.6.8.7. Constraining Design Partition Ports
3.6.8.4. Multicycle Paths x
3.6.8.4.1. Common Multicycle Applications 3.6.8.4.2. Relaxing Setup with Multicycle (set_multicyle_path) 3.6.8.4.3. Accounting for a Phase Shift (-phase)
3.6.8.5. Multicycle Exception Examples x
3.6.8.5.1. Default Multicycle Analysis 3.6.8.5.2. End Multicycle Setup = 2 and End Multicycle Hold = 0 3.6.8.5.3. End Multicycle Setup = 2 and End Multicycle Hold = 1 3.6.8.5.4. Same Frequency Clocks with Destination Clock Offset 3.6.8.5.5. Destination Clock Frequency is a Multiple of the Source Clock Frequency 3.6.8.5.6. Destination Clock Frequency is a Multiple of the Source Clock Frequency with an Offset 3.6.8.5.7. Source Clock Frequency is a Multiple of the Destination Clock Frequency 3.6.8.5.8. Source Clock Frequency is a Multiple of the Destination Clock Frequency with an Offset
3.7. Timing Analyzer Tcl Commands x
3.7.1. The quartus_sta Executable 3.7.2. Collection Commands
3.7.2. Collection Commands x
3.7.2.1. Wildcard Characters 3.7.2.2. Adding and Removing Collection Items 3.7.2.3. Query of Collections 3.7.2.4. Using the get_pins Command
1. Answers to Top FAQs
2. Timing Analysis Introduction
3. Using the Intel® Quartus® Prime Timing Analyzer
A. Intel® Quartus® Prime Pro Edition User Guides

3.5.1.1. Report Fmax Summary

The Timing Analyzer Reports > Datasheet > Report Fmax Summary command generates a report panel showing the potential maximum frequency for every clock in your design. The Fmax column reports the fastest frequency that your clock can run, and still pass report_timing -setup -intra_clock with a slack of 0. The equivalent console command is report_clock_fmax_summary.
Fmax Summary Report


Note: The related get_clock_fmax_info command returns a Tcl list, which is useful for scripting and parsing. Refer to get_clock_fmax_info (::quartus::sta) in Intel Quartus Prime Pro Edition User Guide Scripting.

Timing analysis only computes fMAX for paths where the source and destination registers or ports are driven by the same clock. Timing analysis ignore paths of different clocks, including generated clocks. For paths between a clock and its inversion, the Timing Analyzer computes fMAX as if the rising and falling edges of the clock scale along with fMAX, such that duty cycle (by percentage) is maintained.

However, the Fmax report does not indicate whether your design meets timing for recovery, removal, nor setup or hold without the intra_clock option. For these reasons, always make sure to view the Setup, Hold, Recovery, Removal, and Min Pulse Width slack summaries to determine whether your design meets timing.

The Restricted Fmax column reports the lesser of the following values:

  • The fastest frequency that your clock can run, and still pass report_timing -hold -intra_clock with a slack of 0 or report_min_pulse_width with a slack of 0.
  • The Fmax column value.2

Restricted Fmax considers hold timing in addition to setup timing, as well as minimum pulse and minimum period restrictions. Similar to unrestricted fMAX, the analysis computes the restricted fMAX as if the rising and falling edges of the clock scale along with fMAX, such that the duty cycle (in terms of a percentage) is maintained.

The Restricted Fmax may display text indicating any of the following limiting factors:

  • Limit due to hold check
  • Limit due to minimum pulse width restriction
  • Limit due to high minimum pulse width restriction
  • Limit due to low minimum pulse width restriction

Typically, hold checks do not limit the maximum frequency (fMAX) because the checks are for same-edge relationships, and therefore independent of clock frequency. For example, when launch equals zero and latch equals zero. However, with an inverted clock transfer, or a multicycle transfer, the hold relationship is not a same-edge transfer and changes with the clock frequency.

Refer to the timing reports, such as those that you can generate using report_timing, or using minimum pulse width reports via the report_min_pulse_width command for details of specific paths, registers, or ports.

Related Information
2 The Restricted Fmax column never reports a value higher than the Fmax column.
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