AC Coupler Shielding Structure for Spectrometer Signal Fidelity
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Solution Overview
Problem
Conventional AC couplers for spectrometers suffer from poor signal fidelity, reduced mass resolution, and false ion identification due to signal distortion, reflection, and impedance issues, particularly when handling high-frequency components with large DC offset voltages.
Innovation Solution
The AC coupler design features a signal conductor with capacitors for blocking DC components and a shielding structure with a wider width than the signal conductor to confine electric fields, minimizing reflections and ensuring high-frequency transmission, while maintaining impedance matching and adjustability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional AC couplers are used to block DC components, then DC offset voltages are rejected, but high-frequency signal fidelity deteriorates due to distortion and reflections
Solution Approach 1:
The patent applies local quality by creating a transmission line structure where the shielding structure has different dimensions than the signal conductor, specifically making the shielding structure wider to confine electric fields locally. This localized dimensional differentiation improves high-frequency signal transmission quality while maintaining DC blocking capability through the series capacitors.
Solution Approach 2:
The patent introduces an intermediary transmission line structure between the DC blocking capacitors and the signal path. This transmission line, formed by the signal conductor and shielding structure, acts as a mediator that properly interfaces the blocked DC signal with the high-frequency AC signal path, preventing direct interference and maintaining signal fidelity.
2Device complexity
If standard transmission line dimensions are used, then device complexity is reduced, but impedance matching deteriorates causing signal reflections
Solution Approach 1:
The patent makes the shielding structure wider than the signal conductor in specific regions to create proper impedance matching. This localized dimensional adjustment ensures characteristic impedance continuity along the transmission line, reducing reflections without requiring complex multi-section impedance transformers or additional matching components.
Solution Approach 2:
The patent changes the physical dimension parameter of the shielding structure (making it wider) to optimize impedance matching. This parameter modification adjusts the characteristic impedance of the transmission line to match standard values (e.g., 50 ohms), thereby minimizing reflections and improving signal integrity without adding device complexity.
3Measurement precision
If the shielding structure is made wider to confine electric fields, then signal distortion is reduced, but device area increases
Solution Approach 1:
The patent applies the wider shielding structure only in specific regions where electric field confinement is most needed, rather than uniformly across the entire device. This localized application of the wider shielding structure minimizes the overall area increase while still achieving the goal of reducing signal distortion and confining electric fields effectively.
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 configuration enhances signal fidelity, reduces false ion identification, and improves mass resolution by effectively blocking DC offsets and transmitting high-frequency signals with minimal distortion, leading to more accurate spectrometry results.
Implementation Method 1
a signal conductor capacitor configured to block direct current (DC) components of the wideband signal while transmitting high-frequency alternating current (AC) components
Implementation Method 2
the shielding structure has a width substantially greater than the signal conductor width to confine electric fields and currents in the shielding structure substantially to a region proximate to the signal conductor
Data Source
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AI summary
An AC coupler for transmitting high-frequency components of a wideband signal includes a signal conductor and a shielding structure arranged as a transmission line. The signal conductor includes a conductive element and a capacitor configured to block direct current (DC) components of the wideband signal while transmitting high-frequency alternating current (AC) components of the wideband signal. The shielding structure is configured for conducting at least the AC components of the wideband signal while confining electric fields and currents in the shielding structure substantially to a region proximate to the signal conductor. The shielding structure has a width substantially greater than a width of the signal conductor. The difference between the shielding structure width and the signal conductor width may be substantially greater than an offset distance between the signal conductor and the shielding structure.