Printed Wiring Board Differential Impedance Matching
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Solution Overview
Problem
Existing printed wiring boards with thin insulation layers face signal reflection and wave form distortion due to mismatched differential impedance in various connection forms of signal lines, leading to decreased signal quality.
Innovation Solution
The printed wiring board incorporates a first and second terminal array with differential signal lines, where the line width and interval of the second differential signal line are adjusted to achieve a higher differential impedance compared to the first, ensuring compatibility with termination resistors across different connection forms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a mesh-shaped ground line is provided to suppress capacitance, then signal line width can be maintained, but signal reflection and wave form distortion occur due to impedance mismatch in various connection forms
Solution Approach 1:
The patent applies local quality by setting different differential impedance values for different signal line groups based on their connection forms. Signal lines with 1-to-1 connections use a first differential impedance, while signal lines with 1-to-many connections use a second differential impedance. This localized differentiation resolves the impedance mismatch problem in multi-connection scenarios while maintaining standard line width specifications.
Solution Approach 2:
The patent changes the differential impedance parameter for different signal line groups to match the termination resistor values in their respective connection configurations. By adjusting the differential impedance parameter locally rather than changing line width globally, the patent maintains manufacturing precision while eliminating signal reflection and wave form distortion.
2Adaptability or versatility
If signal lines are connected in 1 to many terminals, then connectivity is improved, but differential impedance cannot be matched to termination resistors causing signal reflection
Solution Approach 1:
The patent implements local quality by assigning different differential impedance characteristics to different signal line groups based on their connection topology. Signal lines connecting to multiple terminals are assigned a second differential impedance that accounts for the capacitive loading effect, while 1-to-1 connections use a first differential impedance. This localized adaptation enables both connection flexibility and signal integrity.
Solution Approach 2:
The patent changes the differential impedance parameter for signal lines with 1-to-many connections to compensate for the increased capacitance from multiple terminal connections. This parameter adjustment ensures that the differential impedance matches the termination resistor values, preventing signal reflection and wave form distortion while maintaining the desired connection flexibility.
Data Source
AI summary
A printed wiring board includes a first terminal array and a second terminal array comprising a plurality of terminals, a first differential signal line connecting a first terminal of the first terminal array to a predetermined number of terminals including a second terminal of the second terminal array, a second differential signal line connecting a third terminal of the first terminal array to a number of terminals including a fourth terminal of the second terminal array, which is bigger than the predetermined number of terminals wherein at least one of a line width and a line interval of one pair signal lines configuring the first differential signal line and the second differential signal line is determined so that differential impedance of the second differential signal line becomes higher compared with differential impedance of the first differential signal line.