Filtered Feed-Through ESR Measurement Without RF Shielding
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Solution Overview
Problem
Conventional methods for measuring insertion loss at high frequencies in filtered feed-through assemblies for implantable medical devices are inaccurate and costly, particularly due to the need for radio frequency shielding, which limits scalability and reliability.
Innovation Solution
A testing system that measures insertion loss and equivalent series resistance (ESR) at multiple frequencies, using a test fixture with pogo pins to secure connections and regression analysis to predict ESR limits, allowing for accurate quality control without shielding, thereby enhancing measurement accuracy and reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a RF shield is welded to the filtered feed-through assembly for insertion loss measurement, then measurement reliability is improved, but manufacturing cost increases and productivity decreases
Solution Approach 1:
The patent extracts the essential measurement function from the complex RF shielded setup by identifying that insertion loss can be calculated from separate ESR and capacitance measurements. This removes the need for the RF shield and welding operations, enabling direct measurement of the feed-through assembly without additional components that hinder mass production.
Solution Approach 2:
The patent replaces the mechanical welding process and physical RF shield structure with an electrical measurement approach. Instead of physically isolating the assembly with shields and welds, the system uses electrical measurements of ESR and capacitance combined with regression analysis to predict insertion loss, substituting a mechanical/physical system with an electrical/mathematical one.
2Reliability
If a RF shield is welded to the filtered feed-through assembly for insertion loss measurement, then measurement reliability is improved, but manufacturing cost increases
Solution Approach 1:
The patent extracts the essential measurement function from the complex RF shielded setup by identifying that insertion loss can be calculated from separate ESR and capacitance measurements. This removes the need for the RF shield and welding operations, enabling direct measurement of the feed-through assembly without additional components that hinder mass production.
Solution Approach 2:
The patent replaces expensive, complex RF shield assemblies with simple, inexpensive electrical measurement probes. The measurement system uses basic electrical components and regression analysis rather than costly RF shielding materials and welding processes, making the measurement approach economically viable for mass production.
3Productivity
If insertion loss is measured without a RF shield, then productivity is improved, but measurement precision deteriorates
Solution Approach 1:
The patent introduces regression analysis as an intermediary computational method that bridges the gap between simple electrical measurements and the complex insertion loss parameter. By using regression equations that correlate ESR and capacitance measurements to insertion loss values, the system achieves accurate results without requiring complex RF measurement setups.
Solution Approach 2:
The patent changes the measurement parameters from direct insertion loss measurement at high frequencies to separate measurements of ESR and capacitance at lower frequencies. This parameter transformation allows measurements to be made without RF shields while maintaining accuracy through the established mathematical relationships between these parameters.
Data Source
AI summary
A determination of an equivalent series resistance (ESR) effect for high frequency filtering performance of a filtered feed-through assembly is described. A low frequency signal is introduced to a filtered feed-through assembly. ESR limit of the filtered feed-through is determined based on the low frequency signal.