Impedance Compensation Structure for Near-Field Magnetic Probe
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The impedance changes caused by signal vias in magnetic field probes affect the high-frequency band characteristics, leading to signal integrity issues and limited frequency bands in near-field magnetic field tests.
Innovation Solution
An impedance compensation structure is introduced using a coaxial via array around the signal via, with evenly distributed grounding vias connected to the shield planes, achieving impedance matching and maintaining constant impedance across a wide frequency band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a signal via is used to connect the CB-CPW core conductor and the strip line, then the magnetic field probe can be manufactured using PCB printed circuit board process, but the impedance of the signal line changes due to the parasitic effect of the signal via hole, affecting the high frequency band characteristics
Solution Approach 1:
The signal via is segmented into multiple sections with different impedance values. The via is divided into a first section with first impedance and a second section with second impedance, allowing each section to be optimized for different frequency ranges and reducing overall parasitic effects
Solution Approach 2:
Different sections of the signal via are assigned different impedance characteristics tailored to specific frequency requirements. The first section has impedance optimized for lower frequencies while the second section has impedance optimized for higher frequencies, creating local quality variations along the via path
2Device complexity
If a conventional signal via structure is used, then the probe structure is simple, but the impedance mutation at the via hole position limits the available frequency band of the near-field magnetic-field test probe
Solution Approach 1:
The via structure transitions from a static single-impedance design to a dynamic multi-impedance design where different sections provide different impedance values. This dynamic impedance profile allows the via to maintain signal integrity across a broader frequency range, extending the probe's operational bandwidth
Solution Approach 2:
The impedance parameter is changed along the length of the signal via, creating a gradient or stepped impedance structure. This parameter variation compensates for parasitic effects at different frequencies, allowing the probe to operate effectively from 300 kHz to 20 GHz
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
The coaxial via array effectively compensates for impedance changes, extending the working frequency band of the magnetic field probe from 300 kHz to 20 GHz, improving signal integrity and sensitivity while reducing electric field coupling.
Implementation Method 1
preset a broadband impedance compensation for the impedance on the position of the via hole, so as to solve the signal integrity problem caused by the sudden change of the impedance
Implementation Method 2
due to the parasitic effect of the signal via hole, the impedance of the signal line is affected
Implementation Method 3
reducing electric field coupling
Data Source
AI summary
An impedance compensation structure for a broadband near-field magnetic-field probe, includes: a signal via; and a plurality of grounding vias provided around the signal via to form a coaxial via array; wherein the grounding via and the signal via have an identical size, all distances of each of the plurality of the grounding vias to the signal via are equal, and the plurality of the grounding vias forms a circle centered at the signal via; wherein each of the plurality of the grounding vias is connected with a magnetic field probe top layer shield plane and a magnetic field probe bottom layer shield plane; each of the plurality of the grounding vias keeps in a conducting state from a direct current to a high frequency, in such a manner that impedance matching of the broadband near-field magnetic-field probe is achieved.