Current Sensing Probe With Impedance Matching Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional current sensing probes face bandwidth limitations and impedance mismatch issues, leading to inaccurate measurements and disturbance of AC current flow, particularly at high frequencies.
Innovation Solution
A current sensing probe with an inductive current sensing element and a current-to-voltage conversion circuit that includes an operational amplifier, coupling capacitor, and resistors, which provides stable impedance matching and transimpedance gain across a wide frequency range, minimizing insertion loss and maintaining operational stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If passive current sensing probes use frequency compensating elements (inductors and capacitors), then signal amplitudes are boosted at low or high frequency ends, but bandwidth improvement is very limited and frequency response remains restricted
Solution Approach 1:
The patent employs dynamic impedance matching through a current-to-voltage conversion circuit with operational amplifiers that automatically adjust their behavior based on frequency. The circuit includes feedback mechanisms that maintain optimal impedance matching across a wide frequency range, allowing the probe to adapt to different frequency conditions without manual adjustment or fixed components.
Solution Approach 2:
The invention changes the impedance parameters dynamically through the conversion circuitry. By converting current to voltage with controlled impedance transformation, the circuit maintains consistent performance across frequency variations. The operational amplifier circuit adjusts its effective impedance based on the input signal characteristics, enabling wide bandwidth operation.
2Measurement precision
If active current sensing probes are designed to minimize insertion loss, then measurement accuracy improves, but sensitivity parameter is sacrificed
Solution Approach 1:
The patent implements feedback mechanisms in the current-to-voltage conversion circuit that continuously monitor and adjust the circuit operation. The feedback loops ensure that impedance matching is maintained while preserving sensitivity, allowing the circuit to compensate for any signal loss and maintain accurate measurements without sacrificing sensitivity for minimal insertion loss.
Solution Approach 2:
The circuit dynamically adjusts impedance parameters through the operational amplifier configuration, maintaining optimal balance between insertion loss and sensitivity. The feedback-controlled impedance transformation ensures that both measurement accuracy and sensitivity are preserved across the operating range.
3Adaptability or versatility
If conventional active current sensing probes are used, then some limitations of passive probes are addressed, but impedance mismatch issues cause insertion loss and modify current flow in the DUT
Solution Approach 1:
The patent introduces an intermediary current-to-voltage conversion circuit that acts as a buffer between the sensing element and the measurement system. This intermediary circuit transforms the current signal while maintaining impedance matching, preventing direct interaction that would cause insertion loss or current disturbance in the DUT.
Solution Approach 2:
The invention replaces direct electrical connection (mechanical/electrical system) with a converted voltage signal system. By converting current to voltage through the operational amplifier circuit, the probe avoids direct current draw from the DUT while maintaining measurement capability, thus eliminating insertion loss and current disturbance.
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 accurate and stable AC current measurements across a wide frequency range, including low frequencies, while minimizing loading on the device-under-test and reducing RF perturbances.
Implementation Method 1
The coupling capacitor is disposed between the inductive current sensing element and a negative input terminal of the operational amplifier
Implementation Method 2
an inductive current sensing element... to measure AC current flowing through a conductor
Data Source
AI summary
Generally, in accordance with the various illustrative embodiments disclosed herein, a current sensing probe includes a current-to-voltage conversion circuit that not only presents a desirable impedance into an inductive current sensing element of the current sensing probe, but also remains operationally stable over a wide range of frequencies when measuring a current flowing through a device-under-test. The wide frequency range can extend down to some low frequencies that can prove challenging to conventional current sensing probe circuits.