From specification to layout
The whole journey in one page: what each step does and what it hands to the next.
A digital chip is made in a fixed order. Each step takes the result of the one before and adds detail, until what began as a sentence becomes shapes on silicon.
The steps#
| Step | Question it answers | What it produces | In the lab |
|---|---|---|---|
| 1. Specification | What should it do? | A written description: ports, behaviour, timing | docs/DESIGN.md |
| 2. RTL design | How does it do it, cycle by cycle? | SystemVerilog code | rtl/top.sv |
| 3. Verification | Does the code do what the specification says? | A test and its result | Simulate |
| 4. Synthesis | Which logic gates build it? | A netlist of standard cells | Synthesize |
| 5. Physical design | Where does each gate go, and how are they wired? | A layout | Build the chip |
| 6. Sign-off | Is it fast enough, and can it be manufactured? | Timing and rule-check reports | The end of the build |
Why the order matters#
Each step is far slower and more costly than the one before it. A simulation takes seconds. A build takes minutes. A real chip takes months and cannot be changed. So mistakes are hunted as early as possible: a bug found in simulation is cheap, the same bug found in silicon is not.
Front end and back end#
Engineers split the flow in two.
- Front end: specification, RTL and verification. The work is about behaviour.
- Back end: synthesis, physical design and sign-off. The work is about area, speed and manufacturability.
Read on#
Something unclear or missing? Send feedbackSign in and use Feedback to tell us.