Define physics constraints

An overview of Quilter’s Circuit Comprehension step, outlining how to define and validate physics constraints for your PCB layout.

Next up in Quilter's submission process is Circuit Comprehension. This step aims to give Quilter insight into the main physics concerns associated with your design.

The majority of physics constraints can be automatically detected by Quilter

Quilter tries to automatically detect as many constraints as possible by analyzing object classes in your input files and inferring constraints from your project netlist. However, some constraints need to be manually defined.

Refer to the tables below for a summary of the physics constraints supported by Quilter.

Quilter treats all signals not represented in Circuit Comprehension as generic, low-speed digital signals. If your physics constraints are not yet supported by Quilter, we recommend pre-placing or pre-routing them before submission.

Routing constraints

Constraint	Details	Automatic?
Power Nets	Design high-current nets as traces with a specified width or as copper pours.	Automatically detected
Differential Pairs	Generate differential pairs with controlled lengths and impedances for high-speed digital signals.	Automatically detected
Single-ended Impedance Control	Impedance-controlled nets for RF nets or other fast, long, or sensitive traces.	Manual
Timing-sensitive Signals	Length matching for timing-sensitive interfaces such as DDR memory	Manual

Placement constraints

Constraint	Details	Automatic?
Crystal Oscillators	Position oscillators close to their drivers to minimize phase noise and startup issues.	Automatically detected
Switching Converters	Ensure tight ground return loops for input and output paths to reduce EMI and voltage ripple.	Automatically detected
Bypass Capacitors	Ensure a stable, low-impedance signal path for power pins.	Automatically detected

Validating constraints

Quilter uses Physics Rule Checks (PRCs) to determine if constraints defined in Circuit Comprehension are correctly implemented in each layout.

You can find more information about the Physics Rule Checks provisioned for each constraint listed above in Physics Rule Checks (PRCs).