Patterned Ground Structure Filters for EMI Suppression
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Solution Overview
Problem
Existing differential signaling technologies face challenges with common-mode interference signals and EMI radiation, particularly above the gigahertz frequency range, due to imperfections and mismatches in signal paths, which degrade signal integrity and require multiple surface-mounted filters, increasing cost and PCB size.
Innovation Solution
The implementation of patterned ground structure (PGS) filters integrated into the PCB, which include resonators and signal traces separated by dielectric material, providing deeper notch suppression of common-mode interference and reducing EMI radiation without consuming valuable PCB space, and can be shielded for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple surface-mounted filters are used to suppress common-mode interference signals, then interference signal rejection is improved, but PCB space consumption and device complexity increase
Solution Approach 1:
The patent combines multiple filter functions into a single integrated patterned ground structure filter. The PGS filter integrates resonators, signal traces, and ground connections into one unified structure that provides common-mode interference suppression equivalent to multiple surface-mounted filters, thereby reducing PCB space consumption while maintaining interference rejection performance
Solution Approach 2:
The patterned ground structure filter serves multiple functions simultaneously: it acts as a common-mode filter, provides signal routing, establishes ground references, and creates resonant cancellation effects. This multi-functionality eliminates the need for separate surface-mounted filters, reducing both PCB space and device complexity
2Object-generated harmful factors
If multiple surface-mounted filters are used to reduce EMI radiation, then EMI suppression is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges EMI suppression functionality into the fundamental ground structure itself. The patterned ground structure integrates EMI filtering, signal routing, and grounding into a single design, eliminating the need for separate EMI filters and reducing overall device complexity
Solution Approach 2:
The patent converts the potentially harmful common-mode currents into beneficial resonant effects. By designing resonators with specific dimensions and configurations, the common-mode currents are transformed into resonant frequencies that create electromagnetic fields opposing the harmful radiation, thereby converting EMI problems into EMI solutions
3Object-generated harmful factors
If differential signal paths are made identical to achieve perfect field cancellation, then EMI radiation is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent intentionally introduces controlled asymmetry through resonator design. Rather than requiring perfectly symmetric signal paths, the resonators are designed with specific asymmetric dimensions and configurations that create targeted electromagnetic fields for cancellation, reducing the stringency of manufacturing precision requirements while maintaining EMI suppression effectiveness
Solution Approach 2:
The patent uses parameter optimization of resonator dimensions, positions, and geometries to achieve EMI cancellation. By carefully selecting resonator parameters such as length, width, and spacing, the system achieves effective field cancellation without requiring perfect symmetry, thereby relaxing manufacturing precision constraints
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
PGS filters offer improved interference signal rejection and reduced EMI radiation, allowing for higher frequency operation with lower voltage requirements, while maintaining signal integrity and reducing the need for multiple filters, thus optimizing PCB space and cost.
Implementation Method 1
The resonator has an L-shape with a first dimension and a second dimension in a plane of the printed circuit board... providing deeper notch suppression of common-mode interference
Implementation Method 2
A portion of the signal trace is situated over the resonator and separated by a distance from the resonator by a dielectric material
Data Source
AI summary
Disclosed herein are printed circuit boards (PCBs) with patterned ground structure filters and data storage devices comprising such PCBs. Each PCB comprises a resonator having an L-shape or a zig-zag shape in a plane of the printed circuit board and at least one signal trace. The resonator has a first dimension and a second dimension in the plane of the printed circuit board. A portion of the at least one signal trace is situated over the resonator and is separated by a distance from the resonator by a dielectric material. In some embodiments, at least part of the portion of the at least one signal trace extends in a same direction as the first dimension (in the case of an L-shaped resonator) or tracks the zig-zag shape of the resonator (in the case of a zig-zag-shaped resonator).