Compliant Cable Termination for PCB Impedance Matching
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Solution Overview
Problem
Existing cable terminations suffer from impedance mismatches and signal reflections, particularly at the interface between cables and printed circuit boards, leading to high-frequency attenuation and limited bandwidth due to long transitions and the need for through holes, which complicates the design of controlled-impedance environments.
Innovation Solution
A cable termination system using compliant contacts that mate directly with conductive pads on electrical devices, employing an anchor block, compliant signal and ground contacts, and a clip to provide strain relief and compliant pressure, allowing for removably attached assemblies that maintain controlled impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cable terminations with through holes and long transitions are used, then mechanical connection and mounting are achieved, but impedance mismatches and signal reflections occur leading to high-frequency attenuation
Solution Approach 1:
The patent removes through holes from the PCB termination structure, extracting the problematic element that caused impedance mismatches and signal reflections. The cable connector is mounted directly on the PCB surface without penetrating through holes, eliminating the discontinuity in the controlled-impedance environment while maintaining mechanical connection and electrical connectivity.
2Ease of manufacture
If through holes are used for mounting cable terminations, then mechanical attachment is achieved, but controlled-impedance environment design becomes difficult
Solution Approach 1:
The patent extracts the through hole element from the mounting structure, replacing it with a surface-mount approach. The cable connector is attached to the PCB surface using surface-mounted components and conductive paths, eliminating the need for through holes while maintaining ease of manufacture through standard surface-mount technology processes.
3Ease of operation
If long transitions are used in cable terminations, then mechanical connection is achieved, but signal reflections increase inhibiting higher frequency signals
Solution Approach 1:
The patent minimizes the transition length between the cable connector and the PCB controlled-impedance environment by using direct surface-mount attachment and optimized conductor paths. This 'skips' over the long transition problem by creating a direct, short electrical path that reduces signal reflections and maintains bandwidth for higher frequency signals.
Data Source
AI summary
A controlled-impedance cable assembly for removably attaching a controlled-impedance cable to a surface of a device. Signal contacts are attached to signal conductors of cables and ground members are coupled to shields of the cables. Ends of the signal conductors and of elongated appendages extending from the ground members are positioned to make a pressure contact to pads and ground lands on the surface. Pressure to make those contacts may come from deflection of the ends of the signal conductors and elongated ground appendages or from a spring. The signal contacts and elongated appendages may be positioned to provide an impedance matching an impedance with the cables.