Impedance Matching Structures for Millimeter Wave Signal Transmission
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Solution Overview
Problem
Electronic devices face challenges in supporting millimeter and centimeter wave communications due to substantial attenuation and distortion of signals, as well as impedance discontinuities in radio-frequency transmission line paths, which limit the efficiency of wireless communications circuitry.
Innovation Solution
The implementation of wireless circuitry with a dielectric substrate, radio-frequency transceiver circuitry, and antennas, along with impedance matching structures such as a ring-shaped fence of conductive vias and landing pads, to match the impedance of coaxial cables to striplines, ensuring efficient signal transmission across a wide frequency band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If impedance matching structures are added to match impedance between coaxial cable and stripline, then signal reflection is reduced and transmission efficiency is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent combines multiple impedance matching structures (fence of conductive vias, landing pads, and dielectric substrate volume) into a single integrated structure embedded within the dielectric substrate. This merging approach achieves effective impedance matching between coaxial cable and stripline while reducing the number of discrete components and simplifying the overall device structure.
Solution Approach 2:
The patent introduces an intermediary impedance matching structure that mediates between the coaxial cable and stripline interfaces. This intermediate structure, consisting of conductive vias and landing pads embedded in the dielectric substrate, serves as a transition zone that gradually transforms the impedance from one medium to another, minimizing signal reflection and improving transmission efficiency.
2Productivity
If impedance matching structures are added to reduce signal reflection, then wireless communications efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs parameter changes in the design of the impedance matching structure, specifically adjusting the dimensions of the landing pads, the spacing and diameter of the conductive vias in the fence, and the volume of the dielectric substrate. By optimizing these parameters, the structure achieves effective impedance matching over a relatively large bandwidth, reducing signal reflection while maintaining manufacturability within standard precision tolerances.
Solution Approach 2:
The patent applies local quality by creating a specialized region within the dielectric substrate where the impedance matching structures are embedded. This local area, defined by the landing pads and conductive vias, has specific electromagnetic properties that differ from the surrounding substrate, enabling effective impedance transformation at the critical interface between coaxial cable and stripline without affecting the overall manufacturing process.
Data Source
AI summary
An electronic device may be provided with a transceiver, a substrate, and antennas mounted to the substrate. The transceiver and antennas may convey signals between 10 GHz and 300 GHz. A radio-frequency connector may be mounted to the substrate. A coaxial cable may couple the transceiver to the connector. A stripline in the substrate may couple the connector to the antennas. Impedance matching structures may be embedded in the substrate for matching an impedance of the stripline to an impedance of the coaxial cable. The impedance matching structures may include a fence of conductive vias, landing pads, and a volume of the dielectric substrate defined by the fence of conductive vias and the landing pads. The impedance matching structures may be configured to perform impedance matching over a relatively wide bandwidth that includes the frequency band of operation for the antennas.