Self-Connected LC Filter Resonators for Compact RF Design
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Solution Overview
Problem
Lumped element LC filters face challenges due to high labor intensity and cost from ribbon bonding, along with significant variations in inductance and capacitance values, leading to degraded unit-to-unit tracking performance.
Innovation Solution
An LC filter design where resonator elements are self-connected, reducing the need for external ribbon bonding, featuring a dielectric substrate with a patterned metal layer and ground plane, integrating shunt and coupling inductors directly into the structure without external connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If lumped elements are connected using ribbon bonding techniques, then the filter can be assembled, but the labor intensity and cost increase significantly
Solution Approach 1:
The patent merges the inductor and capacitor connections by forming both elements within the same continuous metal layer on the substrate. This integration eliminates the need for separate ribbon bonding operations to connect discrete components, directly reducing labor intensity while maintaining filter functionality.
Solution Approach 2:
The filter structure is designed to be self-connecting, where the metal layer patterns automatically provide both the inductive and capacitive elements with their interconnections. The structure serves its own assembly needs by requiring no external ribbon bonding, thereby eliminating the labor-intensive connection process.
2Ease of manufacture
If lumped elements are connected using ribbon bonding techniques, then the filter can be assembled, but the cost increases
Solution Approach 1:
The patent combines multiple discrete components into a single integrated structure where inductors and capacitors share common metal layer patterns. This merging eliminates the need for expensive ribbon bonding materials and processes, directly reducing manufacturing cost while maintaining assembly capability.
Solution Approach 2:
The self-connecting structure eliminates the need for external connection materials like ribbons, thereby removing the associated material costs and processing expenses. The filter structure provides its own interconnections through strategically patterned metal layers, reducing overall manufacturing cost.
3Adaptability or versatility
If lumped inductors and capacitors are used with varied L and C values, then the filter can be constructed, but the unit-to-unit tracking performance degrades
Solution Approach 1:
The patent merges the construction of inductors and capacitors into a unified metal layer pattern process. Since both elements are formed in the same layer using the same fabrication steps, variations in L and C values are correlated rather than independent, enabling consistent performance across production batches and improving unit-to-unit tracking.
Solution Approach 2:
The patent changes the fabrication approach from assembling discrete components with varying parameters to forming integrated elements through controlled metal layer patterning. By adjusting geometric parameters of the metal patterns (trace widths, lengths, spacing), precise L and C values are achieved with tight tolerances, ensuring consistent performance across units.
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 approach results in a low-cost, high-accuracy filter with reduced assembly errors and improved repeatability, providing more predictable RF performance and a compact design.
Implementation Method 1
at least one shunt capacitor having a first electrode formed by a selected region of the metal layer and a second electrode formed by the ground plane
Implementation Method 2
at least one inductor that is formed integrally with the metal layer
Implementation Method 3
a dielectric substrate having first and second opposing faces
Data Source
AI summary
An LC filter structure and method for its fabrication, in which multiple shunt capacitors, multiple shunt inductors and multiple coupling inductors are printed on a metal layer formed on a thin dielectric substrate. The capacitors have first electrodes that are formed as spatially separated regions of the metal layer, and a common second electrode formed by a ground plane on the substrate. The shunt inductors are formed as spiral traces connected to the separated regions and to the ground plane, through conductive vias. The coupling inductors are similarly formed as spiral traces in the gaps between the separated regions, the ends of each coupling inductor being connected to respective adjacent regions of the metal layer.