Contactless Interconnect Using Parallel Transmission Lines
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Solution Overview
Problem
Existing contactless interconnects, such as capacitive couplers, face challenges in achieving reliable high-frequency performance due to parasitic losses and variations in dielectric thickness, which affect signal amplitude and noise ratio, especially in interconnects between printed-circuit boards (PCBs).
Innovation Solution
The use of parallel transmission lines with capacitive and inductive coupling, where the transmission lines are placed in close proximity with an air gap, allowing for efficient energy transfer through capacitive and inductive effects, with matched termination resistors to minimize reflections and enhance noise margins, thereby improving signal integrity and reducing parasitic losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive coupler with air gap is used for contactless interconnect, then physical contact is eliminated, but signal attenuation increases due to parasitic losses
Solution Approach 1:
The patent combines capacitive coupling and inductive coupling mechanisms into a unified interconnect structure. The capacitive pads and inductive loops work together to transfer signals, leveraging both electric field and magnetic field effects to overcome the limitations of pure capacitive coupling and reduce signal attenuation.
Solution Approach 2:
The interconnect structure uses composite construction with conductive traces, dielectric layers, and magnetic elements integrated together. This composite approach enables simultaneous capacitive and inductive coupling, improving signal transfer efficiency while maintaining contactless operation.
2Reliability
If dielectric thickness is reduced to increase capacitance, then coupling efficiency improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent introduces a dielectric layer as an intermediary between the capacitive pads and inductive loops. This dielectric mediator enables effective coupling without requiring extremely thin dimensions, as the dielectric material provides the necessary electric field confinement and coupling enhancement while maintaining manufacturable thickness tolerances.
3Reliability
If physical contacts are used for interconnect, then electrical connection is reliable, but frequency performance is limited by contact geometry
Solution Approach 1:
The patent replaces the mechanical contact-based interconnect system with a contactless electromagnetic coupling system. By substituting physical contact with capacitive and inductive field coupling, the system eliminates the frequency-limiting effects of contact geometry while maintaining reliable electrical connection through field-based energy transfer.
4Reliability
If RF modulation is used for contactless interconnect, then signal transmission is achieved, but system complexity and cost increase
Solution Approach 1:
The patent enables the interconnect structure itself to perform signal coupling functions directly through its capacitive and inductive elements, without requiring external RF modulation circuitry. The structure leverages the natural electromagnetic fields generated by digital signal transitions on the traces to achieve contactless coupling, making the system self-sufficient and eliminating complex modulation components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution maintains high data rates with minimal distortion across a wide frequency range, reducing signal attenuation and noise sensitivity, and allows for precise alignment and sliding motion during PCB insertion and removal, ensuring continuous connectivity.
Implementation Method 1
parallel transmission lines with capacitive and inductive coupling, where the transmission lines are placed in close proximity with an air gap, allowing for efficient energy transfer through capacitive and inductive effects
Implementation Method 2
parallel transmission lines with capacitive and inductive coupling, where the transmission lines are placed in close proximity with an air gap, allowing for efficient energy transfer through capacitive and inductive effects
Data Source
AI summary
A contactless connector requires no physical contact. A terminated transmitting transmission line on a first board is parallel to a dual-terminated receiving transmission line on a second board. The boards are placed face-to-face with a small air gap in-between. A driver drives a driven pulse onto a first end of the transmitting transmission line. The driven pulse capacitively induces a positive induced pulse on the first end of the receiving transmission line. As the driven pulse travels from the first end to the second end of the transmitting transmission line, energy is transferred to the induced pulse, which travels down the receiving transmission line. Inductive coupling becomes stronger than capacitive as the length increases, so that at the second end, the induced pulse is negative and then swings positive. A Schmitt trigger receiver on the second end of the receiving transmission line detects the signal.