Synopsys Timing Constraints And Optimization User Guide 2021 _hot_ ✮

If timing constraints are easily met, the tool shifts its focus toward minimizing area and power consumption.

In terms of general optimization, the guide outlines strategies to guide the tool:

: set_input_delay and set_output_delay specify timing requirements at the block boundaries relative to a clock edge.

Automated methodologies to promote SDC from IP level to SoC level. 2. Essential Timing Constraints Setup

Clocks are the primary reference windows for all timing paths. Defining them accurately is the first and most crucial step in any SDC file. Primary Clocks synopsys timing constraints and optimization user guide 2021

This guide is not static; it is the active driver of optimization. In the synthesis process (using ), the tool uses the constraints defined in the SDC file to intelligently map RTL to gates. It creates a netlist that is optimized to meet the specified clock period.

# Check for unconstrained paths, missing clocks, or bad syntax check_timing # Generate a summary of the worst violations in the design report_constraint -all_violators # Output a highly detailed path report for analysis report_timing -delay_type max -max_paths 10 -transition_time -capacitance Use code with caution. Analyzing a Timing Report

The Synopsys Design Constraints (SDC) format is the industry-standard language used to communicate design intent. SDC files use a Tcl-based syntax to describe: Link environments and operating conditions Clock waveforms and characteristics Input and output delays Timing exceptions (false paths, multicycle paths) Design Environment Setup

# Create a divide-by-2 clock generated from SYS_CLK at register output 'clk_div_reg/Q' create_generated_clock -name DIV_CLK \ -source [get_ports clk_in] \ -divide_by 2 \ [get_pins clk_div_reg/Q] Use code with caution. Clock Properties: Skew, Jitter, and Latency If timing constraints are easily met, the tool

# Define a main system clock with a 10ns period and 50% duty cycle create_clock -name SYS_CLK -period 10.0 [get_ports sys_clk] Use code with caution. Generated Clocks

To prevent the optimization engine from over-restructuring logic that requires precise physical placement, use preservation commands.

: Identifying paths that do not need to meet timing (e.g., static signals, asynchronous crossings) using set_false_path Multicycle Paths

Mastering timing constraints and optimization is the most critical step in achieving timing closure for complex digital designs. Using the industry-standard Synopsys Design Constraints (SDC) format, designers communicate timing intent to synthesis tools like Design Compiler (DC) and static timing analysis (STA) engines like PrimeTime. Primary Clocks This guide is not static; it

If data is too slow, the software makes the path shorter or uses faster parts.

Startpoint: reg_data_src_reg (rising edge of SYS_CLK clocked at 0.0ns) Endpoint: reg_data_dest_reg (rising edge of SYS_CLK clocked at 2.0ns) Path Group: SYS_CLK Path Type: max (Setup Check) Point Incr Path ----------------------------------------------------------- clock SYS_CLK (rising edge) 0.00 0.00 clock source latency 0.40 0.40 reg_data_src_reg/CP (gtech_FD1) 0.00 0.40 r reg_data_src_reg/Q (gtech_FD1) 0.18 0.58 f U124/Y (AND2X1) 0.22 0.80 f U199/Y (MUX2X1) 0.31 1.11 r reg_data_dest_reg/D (gtech_FD1) 0.01 1.12 r data arrival time 1.12 clock SYS_CLK (rising edge) 2.00 2.00 clock source latency 0.40 2.40 clock uncertainty -0.15 2.25 reg_data_dest_reg/CP (gtech_FD1) 0.00 2.25 r library setup time -0.08 2.17 data required time 2.17 ----------------------------------------------------------- data required time 2.17 data arrival time -1.12 ----------------------------------------------------------- slack (MET) 1.05 Use code with caution. Key Elements to Inspect:

: When the standard single-cycle timing model is too restrictive, exceptions are used:

The guide emphasizes the rigorous definition of clocks using create_clock to set periods and jitters, as well as input/output delays to account for external interface timing.

Optimization involves balancing multiple design goals concurrently:

Which are you running in your environment?