Microstrip Line Ground Plate Openings for Impedance Matching
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Solution Overview
Problem
As microstrip line structures in microwave integrated circuits face increasing insertion losses and impedance matching challenges due to the reduced vertical distance between the signal line and the ground plane, the ground plane acts as a barrier for tuning the characteristic impedance, limiting the ability to achieve desired performance.
Innovation Solution
A microstrip line structure is fabricated with a ground plate that includes openings shielded by ground patterns, which are formed on a substrate with an interlayer dielectric layer and contact plugs, allowing for improved impedance matching and reduced signal loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the vertical distance between the signal line and the ground plane is reduced to achieve scaling, then the microstrip line structure can be miniaturized, but insertion losses increase and impedance matching becomes difficult
Solution Approach 1:
The ground plane is segmented by introducing openings (via holes) that are shielded by ground patterns on the substrate. This segmentation allows the ground plane to maintain its shielding function while reducing the effective vertical distance in specific regions, thereby minimizing insertion losses without compromising the overall ground plane integrity.
Solution Approach 2:
The ground plate is designed with non-uniform structure - solid ground regions combined with openings shielded by ground patterns. This local quality variation allows different regions of the ground plate to serve different functions: solid regions provide shielding while opened regions reduce vertical distance for better impedance matching and reduced losses.
2Volume of moving object
If the vertical distance between the signal line and the ground plane is reduced, then the microstrip line structure can be scaled down, but the ground plane becomes a barrier for tuning the characteristic impedance
Solution Approach 1:
The ground plane is divided into solid regions and opened regions (with via holes shielded by ground patterns). This segmentation provides flexibility in impedance tuning by allowing designers to adjust the ratio and distribution of solid and opened regions to achieve desired characteristic impedance values while maintaining a compact structure.
Solution Approach 2:
The ground plate structure is made dynamically adjustable through the opening configurations. By varying the size, shape, and distribution of openings shielded by ground patterns, the effective ground plane area is modulated, enabling continuous tuning of characteristic impedance to match different network device requirements.
3Reliability
If a solid ground plane is used to isolate the signal line from the substrate, then substrate-induced losses are reduced, but the ground plane acts as a barrier for impedance matching and signal loss increases
Solution Approach 1:
The ground plate combines solid ground regions for shielding with opened regions (via holes) for reduced signal loss. The ground patterns on the substrate shield the openings, maintaining isolation properties while the opened regions allow better electromagnetic field distribution and reduced insertion losses compared to a completely solid ground plane.
Data Source
AI summary
A method for fabricating microstrip line structure is disclosed. First, a substrate is provided, ground patterns are formed on the substrate, an interlayer dielectric (ILD) layer is formed on the ground patterns, contact plugs are formed in the ILD layer, a ground plate is formed on the ILD layer, and a signal line is formed on the ground plate. Preferably, the ground plate includes openings that are completely shielded by the ground patterns.