Differential Signal Probe Launch Structure for High-Speed PCB
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Solution Overview
Problem
Existing methods for injecting or sensing high-speed differential signals in printed circuit boards face issues such as signal degradation due to large return routes, impedance discontinuities, and physical limitations imposed by the size and height of connectors like SMA adapters, which restrict signal density and placement flexibility.
Innovation Solution
A differential signal probe-launch structure featuring a semi-rigid conductive outer housing with insulated signal pins, vertically extending signal vias, and a conductive ground pad connected to horizontally extending ground plane conductors, providing a short return loop and allowing for a solid, accessible ground plane for consistent measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wire is used to connect the probe ground to the PCB ground via, then the ground connection is established, but the large return route degrades the signal
Solution Approach 1:
The ground connection wire is extracted and replaced by directly connecting the probe outer housing to a ground pad on the PCB, eliminating the large return route through the wire and ground via combination. The ground pad provides a localized ground reference point that minimizes the return path area.
Solution Approach 2:
The ground connection transitions from a three-dimensional wire path through the PCB thickness to a two-dimensional pad surface connection, reducing the return route area by constraining the current flow to a planar path rather than allowing it to loop through the PCB volume.
2Reliability
If an SMA adapter is used for signal injection, then signal transmission is enabled, but the large footprint limits signal density
Solution Approach 1:
Instead of using a bulky SMA adapter that physically interfaces with the PCB, the invention uses a simplified ground pad copy that provides the essential ground reference function without the large connector body, allowing multiple such pads to be placed in close proximity for high signal density.
3Reliability
If an SMA adapter is used for signal injection, then signal transmission is enabled, but the fixed ground pad distance creates impedance discontinuities
Solution Approach 1:
The ground pad location is made dynamic and adaptable rather than fixed by the SMA connector geometry. The ground pad can be positioned optimally near each signal launch point, allowing the return path to be minimized and impedance continuity to be maintained across different signal locations.
4Reliability
If an SMA adapter is used for signal injection, then signal transmission is enabled, but the physical height and size limit placement flexibility
Solution Approach 1:
The bulky SMA adapter body is extracted and removed, retaining only the essential ground reference function through a simple pad connection. This allows the signal launch structure to be placed in locations where even small connectors would not fit, significantly increasing placement flexibility.
Data Source
AI summary
A differential signal probe-differential signal launch structure wherein the conductive outer housing of the differential signal probe is disposed on and electrically connected to a conductive ground pad disposed on a printed circuit board. A vertically extending ground via is provided with the conductive pad being electrically connected to the horizontally ground plane conductors through the vertically extending ground via.