Noise Source Impedance Extraction with Adjustable Current Probes
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Solution Overview
Problem
Existing impedance measurement methods, such as those using a bias tee and current probes, are limited by capacity and frequency range, failing to accurately measure noise source impedance in high-power electronic devices and wide frequency bands, particularly below 1 MHz.
Innovation Solution
Adjusting the number of turns of cables around current probes based on the frequency range to enhance coupling and accuracy, using a Vector Network Analyzer to calculate impedance through S-parameters, and incorporating a Line Impedance Stabilization Network to stabilize line impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bias tee is used to measure noise source impedance, then the measurement can be performed during device operation, but the rated capacity limit of the coupler prevents measurement of high-power devices
Solution Approach 1:
The patent introduces a current probe as an intermediary device to measure impedance. Instead of directly connecting a bias tee to the high-power device, the current probe acts as a mediator that can handle high currents while still enabling impedance measurement through S-parameter analysis, thus resolving the power capacity limitation of conventional couplers
Solution Approach 2:
The patent replaces the traditional bias tee mechanism with a current probe-based measurement system. This substitution allows the measurement system to handle high-power devices by using electromagnetic field coupling through the current probe rather than direct electrical connection, eliminating the rated capacity limit
2Adaptability or versatility
If current probes are used to extend frequency range, then measurement can cover wider frequency bands, but measurement accuracy decreases at low frequencies due to reduced induced voltage
Solution Approach 1:
The patent makes the number of cable turns around the current probe adjustable rather than fixed. This dynamic adjustment allows optimization of the measurement system for different frequency ranges: more turns for low frequencies to increase induced voltage and improve accuracy, fewer turns for high frequencies to maintain bandwidth, thus resolving the accuracy-range trade-off
Solution Approach 2:
The patent changes the physical parameter of cable turns around the current probe to optimize measurement performance. By adjusting this parameter, the system can adapt to different frequency conditions, increasing induced voltage at low frequencies and maintaining accuracy across the extended frequency range
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
Enables accurate impedance measurement across an extended frequency range from 10 kHz to 200 MHz, addressing noise generation and electromagnetic interference in high-power devices like PCs, facilitating EMC compliance and noise prediction.
Implementation Method 1
This technique extracts impedance using variation in an S-parameter measured using two current probes... extracts impedance by utilizing voltage induced by the current probes
Data Source
AI summary
Disclosed herein is an apparatus and method for extracting noise source impedance of an electronic device. The method includes calculating the impedance of the noise source of a measurement target device using a first probe and a second probe, and the number of turns of a cable wrapped around each of the first probe and the second probe may be adjusted based on the frequency range of the noise source.