Planar Balun for MR Systems Using Virtual Ground
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Solution Overview
Problem
Ferrite baluns used in magnetic resonance detection systems suffer from magnetic saturation, making them unsuitable for strong magnetic environments, resulting in high transmission loss and system integration issues.
Innovation Solution
A planar balun formed on a multi-layer circuit board with a first winding and a second winding separated by an insulating layer, utilizing balancing capacitors to set a virtual ground and improve balance, allowing operation in strong magnetic fields without a ferrite magnetic core.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If ferrite material is used to implement the balun for UHF, VHF and lower bands, then the balun can operate at high power, but it forms magnetic saturation and cannot be used in strong magnetic environment
Solution Approach 1:
The patent removes the ferrite magnetic core from the balun structure, extracting the harmful magnetic saturation property while retaining the high power operation capability through air-core or non-magnetic material windings
Solution Approach 2:
The patent changes the material parameter from ferrite (magnetic) to non-magnetic materials, fundamentally altering the magnetic properties of the balun to eliminate saturation while maintaining electrical performance for high power applications
2Reliability
If ferrite balun is placed outside the scan room and connected via cable, then it avoids magnetic saturation, but transmission loss increases and system integration is compromised
Solution Approach 1:
The patent extracts the harmful ferrite material from the balun, allowing the balun to be safely placed inside the scan room without magnetic saturation, thereby eliminating the need for external placement and long cables that cause transmission loss
Solution Approach 2:
The patent merges the balun with the MR detection system by enabling its placement inside the scan room, achieving system integration and eliminating the separation that necessitated cable connections and caused energy loss
3Reliability
If ferrite balun is placed outside the scan room, then magnetic saturation is avoided, but system integration is reduced
Solution Approach 1:
The patent removes ferrite material from the balun construction, eliminating the constraint that forced external placement and enabling integration within the scan room MR detection system
Solution Approach 2:
The patent creates a universal balun design that can operate reliably within the strong magnetic field environment of the scan room, making it adaptable to integrated MR detection system configurations rather than requiring external placement
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 solution enables the balun to maintain balance and operate effectively in strong magnetic environments, reducing transmission loss and facilitating system integration by avoiding ferrite magnetic cores, thus enhancing performance in MR detection systems.
Implementation Method 1
By virtue of the coupling effect between the two inductors of the balun, a differential signal input from the balanced ends can be converted into a single end signal of the unbalanced end
Implementation Method 2
a first balancing capacitor, which is connected between a selected portion near a center of the first winding and the ground potential
Data Source
AI summary
The present invention provides a planar balun and a multi-layer circuit board. The planar balun formed on the multi-layer circuit board comprises: a first winding with at least one turn, which is formed in a first conductive layer, and has a first lead and a second lead serving as a first balanced end and a second balanced end of the balun respectively; a second winding with at least one turn, which is formed in a second conductive layer separated from the first conductive layer by at least a first insulating layer, and has a third lead and a fourth lead, wherein the third lead is connected to a ground potential, and the fourth lead serves as an unbalanced end of the balun; and a first balancing capacitor, which is connected between a selected portion near a center of the first winding and the ground potential.