LTCC Serpentine Capacitor Parasitic Inductance Cancellation
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Solution Overview
Problem
High-frequency capacitors using LTCC materials face challenges with parasitic inductance, leading to insertion losses and complex, costly multilayered structures that complicate their integration into high-frequency circuits.
Innovation Solution
The use of overlapping aligned serpentine conductive pathways within a thin dielectric layer, minimizing parasitic inductance by equal and opposite current flow, and achieving near-ideal high-frequency performance with a simpler structure that can be economically fabricated using standard LTCC techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If multiple internally deposited conductors are stacked alternately between dielectric layers to reduce parasitic inductance, then the capacitor's ESL is reduced, but the device complexity and fabrication cost increase significantly
Solution Approach 1:
The capacitor structure is divided into multiple segments with internally deposited conductors stacked alternately between dielectric layers. Each segment contributes to reducing parasitic inductance through its specific conductor configuration, and the segmented approach allows systematic reduction of ESL while maintaining manageable fabrication complexity.
Solution Approach 2:
Multiple conductors are nested within the dielectric layers in an alternating stacked configuration. The conductors are embedded within the ceramic structure during the LTCC fabrication process, creating a compact nested arrangement that reduces parasitic inductance without requiring excessive external space or complexity.
2Object-affected harmful factors
If multiple extraction electrodes are added to reduce parasitic inductance, then the capacitor's ESL is reduced, but the number of external connections and potential failure points increase
Solution Approach 1:
The extraction electrodes are segmented and distributed across multiple dielectric layers rather than concentrated at single points. This segmentation allows the inductance-reducing effect to be achieved while distributing the connection requirements, reducing the impact of any single connection failure on overall reliability.
Solution Approach 2:
The extraction electrodes are nested within the multilayered dielectric structure, with conductors emerging at strategic points. This nesting approach minimizes the number of external connections required while maintaining the inductance-reducing benefits of the stacked conductor configuration.
3Object-affected harmful factors
If a complex multilayered structure is used to reduce parasitic inductance, then the capacitor's ESL is reduced, but the manufacturing cost and fabrication error risk increase
Solution Approach 1:
The complex structure is broken down into repeatable modular units that can be fabricated using standard LTCC processes. Each layer and conductor pattern is designed to be manufacturable with conventional screen printing and co-firing techniques, reducing fabrication complexity despite the multilayered configuration.
Solution Approach 2:
The conductors and dielectric layers are nested together in a configuration that leverages the LTCC fabrication process strengths. The internal conductors are deposited and embedded during the green tape stacking and co-firing process, eliminating the need for post-fabrication assembly and reducing overall manufacturing complexity.
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 low insertion loss and broad frequency performance for high-frequency lumped capacitors, enabling their reliable integration into filter circuits with reduced manufacturing complexity and cost.
Implementation Method 1
The geometry of partially overlapping extraction electrodes of opposite polarities serves to generate oppositely flowing currents between any two conductors, which separated by thin dielectric layers, serves to cancel out a portion of the magnetic flux generated by the current in each conductor
Implementation Method 2
low temperature co-fired ceramic (LTCC) material as the dielectric
Data Source
AI summary
There is disclosed a low loss and high frequency lumped capacitor that is ideally constructed from LTCC dielectric material and deposited conductive layers. The capacitive plates are shaped as identical and overlapping serpentine conductive paths positioned on either side of a thin dielectric layer, with opposite ends of the conductive paths used for signal contact points. The net effect of the shape of the capacitive plates and the resulting approximately equal and opposite current flows is to cancel the majority of parasitic inductance at high frequencies, thus reducing insertion loss. Filters built using this construction of capacitor exhibit improved high frequency performance. This type of capacitor also has a simplicity of construction that allows integration into LTCC fabricated circuitry without requiring extra layers or terminals.