100 ohm differential impedance recommended design
- Ground package design: line width/spacing 7/5/7mil ground wire width ≥20mil signal and ground wire distance 6mil, add ground vias every 400mil.
- Design without ground package: line width/spacing 10/5/10mil, the distance between the differential pair and the pairis ≥20mil (not less than 10mil in special cases). It is recommended that the entire group of differential signal lines is shielded with grounding, and the distance between the differential signal and the shielding ground ≥35mil (not less than 20mil in special cases).
90 ohm differential impedance recommended design
- Ground package design: line width, line spacing 10/5/10mil ground wire width ≥20mil signal and ground wire distance 6mil or 5mil, add ground vias every 400mil
- Design without ground package: line width, line spacing 16/5/16mil, the distance between the differential pair and the pairis ≥20mil, it is recommended that the entire group of differential signal lines should be shielded with ground, and the distance between the differential signal and the shielding ground ≥35mil (In special cases, it cannot be less than 20mil).
Note: Prioritize the use of package ground design. However, if the line is short and there is a complete ground plane, it can be designed without package ground.
Calculation parameters:
FR-4, thickness 1.6mm+/-10%, dielectric constant 4.4+/-0.2, copper thickness 1.0 oz (1.4mil), solder mask thickness 0.6±0.2mil, dielectric constant 3.5+/-0.3.
Fig.1 Design of ground package Fig.2 Design without ground package