Planar Circuit Unit Cell Design for Spurious Mode Suppression
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Solution Overview
Problem
Existing planar circuits face challenges in preventing the propagation of spurious mode waves, leading to signal leakage and transmission loss, particularly in high-frequency applications, due to the limitations in design flexibility and increased loss characteristics.
Innovation Solution
A planar circuit design featuring two-dimensionally arranged unit cells with rotational symmetry, where the center area serves as a capacitive region and the peripheral area as an inductive region, with spiral-shaped conductor patterns connecting adjacent unit cells, effectively blocking spurious modes and enhancing bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a unit cell pattern with capacitive and inductive regions is arranged to prevent spurious mode waves, then unwanted wave propagation is blocked, but transmission loss increases due to energy leakage
Solution Approach 1:
The patent converts the harmful spurious mode waves into beneficial effects by using periodic unit cell structures that create band gaps. The capacitive and inductive regions within each unit cell work together to reflect unwanted waves while allowing desired signals to pass, thus transforming the problem of wave propagation into a solution for frequency-selective filtering and energy preservation
Solution Approach 2:
The patent optimizes transmission characteristics by adjusting key parameters of the unit cell structure, including the size and configuration of capacitive regions, the geometry of inductive regions, spacing between unit cells, and substrate properties. These parameter changes enable precise control over band gap frequencies and transmission loss characteristics
2Object-affected harmful factors
If a large unit cell is used to achieve desired band gap frequency, then spurious mode blocking is effective, but design flexibility and layout freedom decrease
Solution Approach 1:
The patent divides the electromagnetic shielding function into discrete, repeating unit cell segments. Each unit cell is a self-contained structure with specific capacitive and inductive elements that can be independently designed and then replicated in two-dimensional arrays. This segmentation allows the overall structure to achieve effective spurious mode blocking while maintaining flexibility in layout configuration
Solution Approach 2:
The patent transitions from one-dimensional transmission line structures to two-dimensional periodic arrays of unit cells. This dimensional change enables more effective band gap formation and spurious mode suppression while providing greater design flexibility through varied unit cell arrangements, orientations, and patterns that can adapt to different layout requirements
3Device complexity
If conventional transmission line structures are used, then simple structure is maintained, but signal leakage and interference between neighboring lines occur
Solution Approach 1:
The patent merges multiple functions into a single integrated unit cell structure that simultaneously provides signal transmission, spurious mode suppression, and electromagnetic shielding. The combination of capacitive and inductive regions within each unit cell creates a multifunctional element that maintains structural simplicity while eliminating signal leakage and interference problems associated with conventional separate 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 design significantly reduces signal loss, increases design flexibility, and prevents unwanted coupling between high-frequency circuits, resulting in improved transmission characteristics and reduced size of high-frequency circuit devices.
Implementation Method 1
the combined pattern of rectangular patterns formed at the center and four corners of the unit cell serves as a capacitive region (a capacitance component)
Implementation Method 2
A reduced-width crisscross strip portion of the unit cell serves as an inductive region (an inductance component)
Implementation Method 3
a unit cell pattern including a capacitive region and an inductive region is repeatedly arranged in two-dimensional directions (longitudinal and transverse directions) to prevent such propagation of unwanted waves
Data Source
AI summary
A planar circuit having a conductive film on either main surface of a substrate. The conductive film on one of the main surfaces is patterned with two-dimensionally and repeatedly arranged unit cells, which are basic conductor patterns. Each of the unit cells has a capacitive region at the center thereof. Capacitance is induced between the center area and the conductor film formed on the main surface of the substrate opposite the center area. An area located near the middle of each of sides in the peripheral portion serves as an inductive region. In any two adjacent unit cells, the inductive regions have a multiple spiral-shaped conductor pattern, in which the center ends thereof are connected to each other at a halfway position between the two unit cells, and the outer peripheral ends thereof are connected to the capacitive regions.