Differential Impedance Calculator
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Reference for differential pair impedance targets and routing rules. Numeric differential calculation is temporarily unavailable while the model is validated; single-ended Z0 is available.
What this page can and cannot tell you
Differential impedance depends on trace width, pair spacing, dielectric height, εr and copper thickness together. This page does not compute a numeric result for this topic. Single-ended Z0 below is for an isolated line and must not be read as a differential result.
Assumptions
- Bring a stackup (dielectric heights, εr, copper weight) to the fabricator or field solver.
Limits
- The earlier differential model was not validated and is switched off.
Differential impedance results are temporarily unavailable. The previous differential model was not validated against a field solver or a published source, so it has been switched off until it is. Single-ended Z0 below is for an isolated line and is not a differential result.
Impedance Parameters
MOD: IMP_CAL_V1Differential impedance results are temporarily unavailable. The previous differential model was not validated against a field solver or a published source, so it has been switched off until it is. Single-ended Z0 below is for an isolated line and is not a differential result.
Embedded microstrip results are temporarily unavailable while the model is researched and validated.
Impedance Check
Impedance Control Tips
To Increase Impedance
- • Reduce trace width
- • Increase dielectric height
- • Review laminate dielectric constant
To Decrease Impedance
- • Increase trace width
- • Reduce dielectric height
- • Review laminate dielectric constant
Differential Pair Design Guidelines
Key Design Rules
- • Keep trace spacing consistent throughout the route
- • Maintain constant impedance at bends and corners
- • Avoid routing near board edges or cutouts
- • Use length-matching serpentines if needed
- • Reference to continuous ground plane
Differential Routing Best Practices
Length Matching
Use serpentine routing on the shorter trace to achieve matching. Place serpentines near the source.
Coupling
Tighter spacing increases coupling and reduces differential impedance. Looser spacing reduces coupling. Balance based on crosstalk and impedance requirements.
Via Transitions
When transitioning layers, place vias symmetrically. Add ground vias nearby to maintain return path continuity. Minimize via stub length for high-speed signals.
Need Single-Ended Impedance?
Use our impedance calculator for microstrip and stripline single-ended impedance calculations, or calculate trace width for current capacity requirements.
Differential Impedance FAQ
Can this page calculate differential impedance?
Differential impedance results are temporarily unavailable. The previous differential model was not validated against a field solver or a published source, so it has been switched off until it is. Single-ended Z0 below is for an isolated line and is not a differential result.
How should a differential pair be validated?
Use the interface specification, actual stackup, and a validated coupled-line field solver; confirm the design with your fabricator.
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