Description
Overview: This check calculates the trace length between a bypass capacitor and its associated pin.
Passing Criteria: This check passes is the calculated trace length falls below a specified tolerance
Reporting Units: MICRONS
Examples
Passing Message:
Distance to pin of 4808.02µm within acceptable range (0µm to 10000µm)
Failing Message:
Distance to pin of 61600.51µm outside acceptable range (0µm to 10000µm)
Physics Justification
Minimizing the trace length is important because:
Reduced Parasitic Inductance:
Longer traces add parasitic inductance, which slows the capacitor's ability to respond to high-frequency noise.
Improved Noise Filtering:
A short trace ensures the capacitor can quickly supply or absorb current, effectively stabilizing the voltage and filtering noise.
Lower Impedance Path:
Shorter traces reduce the impedance, maintaining a robust and efficient power delivery to the pin.
Helpful Definitions
Parasitic Inductance
The unintended inductance present which arises from the magnetic field created by current flow and opposes changes in current, especially at high frequencies. It can degrade circuit performance by slowing responses and causing noise.