MRI RF Coil Pre-Amplifier Narrowband Filtering Against Oscillation
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Solution Overview
Problem
Traditional pre-amplifiers for magnetic resonance imaging radio-frequency coils suffer from wide operation bandwidth, leading to excessive gain outside the magnetic resonance signal frequency point, causing oscillation and reduced frequency selectivity, and mismatched impedance between the coil and pre-amplifier.
Innovation Solution
Incorporating a narrow band filter, either an LC filter or a surface acoustic wave filter, integrated with the output matching circuit to create a pre-amplifier that amplifies signals only within a narrow frequency range near the magnetic resonance signal frequency, reducing gain at other frequencies and minimizing oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional pre-amplifier with wide operation bandwidth is used, then the gain is high across a broad frequency range, but the frequency selectivity deteriorates and oscillation occurs outside the magnetic resonance signal frequency point
Solution Approach 1:
The patent changes the bandwidth parameter of the pre-amplifier from wide to narrow by introducing a narrow band filter. This parameter change allows the pre-amplifier to maintain high gain only within a specific frequency range centered on the magnetic resonance signal frequency, thereby improving frequency selectivity and eliminating oscillation at other frequencies
Solution Approach 2:
The patent introduces a narrow band filter as an intermediary component between the amplification circuit and the output matching circuit. This intermediary element selectively passes only the magnetic resonance signal frequency while attenuating other frequencies, thus resolving the contradiction between maintaining gain and preventing oscillation
2Power
If the operation bandwidth is widened to achieve high gain, then the gain at magnetic resonance frequency is improved, but the impedance matching between the coil and pre-amplifier deteriorates
Solution Approach 1:
The patent changes the operational bandwidth parameter from wide to narrow, which allows for better impedance matching at the specific magnetic resonance frequency. The narrow band filter ensures that the pre-amplifier operates optimally only at the resonant frequency, improving the impedance matching between the coil and pre-amplifier while maintaining high gain
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 pre-amplifier achieves the required gain near the magnetic resonance signal frequency while minimizing gain at other frequencies, significantly reducing the likelihood of oscillation and improving signal-to-noise ratio without affecting normal operation.
Implementation Method 1
The structure of a magnetic resonance imaging radio-frequency coil in the prior art is an LC resonance loop
Implementation Method 2
Incorporating a narrow band filter, either an LC filter or a surface acoustic wave filter, integrated with the output matching circuit
Data Source
AI summary
A pre-amplifier for a magnetic resonance imaging radio-frequency coil. The pre-amplifier comprises an input matching circuit (1), an amplification circuit (2), an output matching circuit (3) and a narrow band filter (4) for filtering a magnetic resonance signal amplified through the amplification circuit (2). The present invention has the technical effect that the pre-amplifier for a magnetic resonance imaging radio-frequency coil generates a gain required by magnetic resonance imaging within a very small range near a magnetic resonance signal frequency point, but only generates a very small gain or has no amplification function completely at other frequency points, thereby significantly reducing the possibility of oscillation of the magnetic resonance imaging radio-frequency coil.