Coplanar Waveguide Layout for Low-Loss Millimeter-Wave Signals
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Solution Overview
Problem
The design and fabrication of transmission line structures for high millimeter wave frequencies face challenges due to high insertion loss in silicon-based microstrip transmission lines, which are lossy and inefficient.
Innovation Solution
The use of coplanar waveguide structures with a planar transmission line disposed within a dielectric layer over a high resistivity substrate, featuring conductive signal and ground lines, and conductive stacked signal and ground lines formed by interlacing conductive segments with vias, reduces insertion loss and harmonic distortion, and improves reliability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If microstrip transmission line structures are used on silicon substrate, then the structure is simple and easy to fabricate, but the insertion loss becomes unacceptably high due to lossy silicon substrate
Solution Approach 1:
The patent extracts the transmission line structure from the lossy silicon substrate by introducing a separate lossless dielectric layer. The microstrip transmission line is formed on this dedicated dielectric layer rather than directly on the silicon substrate, thereby extracting the signal path from the harmful lossy environment while maintaining fabrication compatibility with silicon-based processes.
Solution Approach 2:
The patent introduces a lossless dielectric layer as an intermediary between the silicon substrate and the microstrip transmission line. This intermediate layer acts as a mediator that isolates the signal-carrying conductors from the lossy silicon substrate, preventing energy loss while still allowing the structure to be fabricated using standard silicon-based manufacturing techniques.
2Speed
If higher millimeter wave frequencies are used for wireless communication, then the data transmission speed increases, but the insertion loss and attenuation in transmission lines increases significantly
Solution Approach 1:
The patent changes the dielectric parameter of the transmission line environment by introducing a lossless dielectric layer with optimized dielectric constant and loss tangent properties. This parameter change allows the transmission line to maintain low loss characteristics at higher millimeter wave frequencies, enabling faster data transmission without proportionally increasing insertion loss.
3Device complexity
If conventional transmission line structures are used at millimeter wave frequencies, then the design is straightforward, but the harmonic distortion becomes significant and reduces signal quality
Solution Approach 1:
The patent extracts the transmission line from the lossy silicon substrate environment and places it on a dedicated lossless dielectric layer. This extraction reduces nonlinear interactions and parasitic effects that generate harmonic distortion, thereby improving signal quality at millimeter wave frequencies while maintaining relatively simple design procedures.
Data Source
AI summary
A coplanar waveguide structure includes a dielectric layer disposed over at least a portion of a substrate and a planar transmission line disposed within the dielectric layer. In some instances, the planar transmission line can include a conductive signal line and one or more ground lines. In other instances, the planar transmission line may include a conductive stacked signal line and one or more stacked ground lines.