This tutorial is designed for engineers and students who want a practical, step-by-step guide to using Design Compiler (specifically DC 2021.03-SP4). We will move from basic setup to timing closure. Before typing a single command, ensure your environment is ready. The 2021 version introduced stricter TCL 8.6 compliance and deprecated some legacy commands. Environment Variables # In your .bashrc or .cshrc setenv SYNOPSYS_HOME /tools/synopsys/2021.03 setenv PATH $SYNOPSYS_HOME/bin:$PATH setenv SNPSLMD_LICENSE_FILE 27000@license_server setenv LM_LICENSE_FILE 27000@license_server Invocation Launch the tool via the Common UI (recommended for tutorials):
# ---------------------------------------- # Synopsys DC 2021 Tutorial Script # ---------------------------------------- set my_design "riscv_core" set target_library "saed32nm_tt_1p05V_25C.db" set link_library "* $target_library" set search_path ". ./rtl ./libs" Read RTL read_file -format verilog [list $my_design.v memory_controller.v] current_design $my_design link Apply Constraints create_clock -name core_clk -period 5.0 [get_ports clk] set_input_delay -clock core_clk -max 1.5 [all_inputs] -remove [get_ports clk] set_output_delay -clock core_clk -max 1.5 [all_outputs] Pre-compile checks check_design check_timing Compile compile_ultra -timing Reports report_timing > reports/$my_design.timing report_area > reports/$my_design.area Save write -format verilog -output outputs/$my_design.v write_sdc outputs/$my_design.sdc synopsys design compiler tutorial 2021
# Save the synthesized design write -format ddc -hierarchy -output outputs/final.ddc write -format verilog -hierarchy -output outputs/final_netlist.v Save SDC constraints (for placement & routing) write_sdc outputs/constraints_out.sdc Step 9: Common Pitfalls in the 2021 Version 1. "Undriven port" warnings Fix: Use set_driving_cell on all input ports. DC 2021 is stricter about floating inputs. 2. "DesignWare license not found" Fix: Ensure synthetic_library is set correctly. Without this, you get "Unknown operator" errors for + , - , * . 3. Hold time violations reported after compile Note: DC 2021 does not fix hold timing. It only fixes setup. Hold fixes happen in PrimeTime or ICC2 using clock tree insertion. Ignore hold violations in DC unless they are > 0.5ns. Step 10: Full Script Example (run.tcl) Save this as run_synthesis.tcl and execute with dc_shell -f run_synthesis.tcl . This tutorial is designed for engineers and students
The synthetic_library for DesignWare is crucial. If you miss this, your multiplier or ALU synthesis will fail. Step 3: Reading the RTL (Two Methods) You can read Verilog, VHDL, or SystemVerilog. For 2021, read_verilog and read_vhdl are stable, but the recommended TCL command is read_file . Method A: Read and Elaborate read_file -format verilog top_module.v alu.v register_file.v current_design top_module link Method B: Analyze & Elaborate (Better for VHDL or mixed) analyze -format verilog -lib WORK top_module.v alu.v elaborate top_module -lib WORK After reading, check for generic mapping: The 2021 version introduced stricter TCL 8
Introduction: The Heart of Digital Synthesis For over three decades, Synopsys Design Compiler (often abbreviated as dc_shell ) has remained the gold standard for RTL synthesis. If you are an ASIC or FPGA designer, mastering this tool is non-negotiable. While newer versions (2022, 2023, 2024) have added incremental features like better multicore support and cloud integration, the 2021 release represents a mature, stable, and widely adopted version in many production tape-outs.