Differential Probe Characterization With Balanced Signal Lines
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Solution Overview
Problem
Characterizing symmetric or differential measurement probes using asymmetric test signals leads to inaccurate results due to parasitic effects, as these signals do not accurately represent the frequency response of the probes, making it difficult to compensate for disturbances caused by parasitic elements.
Innovation Solution
A test device and method that apply a symmetric test signal to a differential or symmetric probe by connecting one terminal to a main signal line and the other to a symmetrical signal line, both terminated with well-defined impedances, avoiding direct grounding to provide a precise characterization of the probe's properties, such as impedance and frequency response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an asymmetric test signal is used to characterize a symmetric probe, then the test setup is simple, but the measurement precision deteriorates due to parasitic effects and frequency response mismatch
Solution Approach 1:
The patent applies asymmetry principle by intentionally creating a symmetric test environment for symmetric probes. Instead of using asymmetric ground-based signals, the invention uses two balanced signal lines with equal impedance terminations to create a symmetric test configuration that matches the probe's differential nature, thereby eliminating parasitic effects and achieving accurate frequency response measurement
Solution Approach 2:
The patent changes the test signal parameters from asymmetric ground-referenced signals to symmetric differential signals. By modifying the signal configuration to have equal amplitude and opposite polarity on both lines, with balanced impedance terminations, the test signal parameters are adjusted to match the probe's operational characteristics, enabling precise characterization
2Device complexity
If one terminal of the probe is directly connected to ground in asymmetric configuration, then the test arrangement is simplified, but the reliability of probe characterization deteriorates due to inaccurate frequency response representation
Solution Approach 1:
The patent applies equipotentiality principle by creating a balanced potential distribution in the test arrangement. Both signal lines are terminated with equal impedance values referenced to ground, creating symmetric potential conditions that accurately represent the probe's differential operation. This balanced configuration ensures that neither line has a direct ground connection, maintaining equipotential symmetry and eliminating ground loop parasitics
Data Source
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AI summary
Device and method for analyzing a probe (100), in particular for analyzing a symmetrical, differential probe. A ground-based test signal is provided to a main signal line (11), wherein the main signal line is terminated by a predetermined impedance (R1). Furthermore, at least one additional signal line is provided (21), wherein a further impedance (R2) is arranged between the additional signal line and the ground. Accordingly, a differential probe may measure a differential signal between the main signal line and the additional signal line. Hence, no grounded signal is provided to the probe. This measurement of the probe can be compared with a reference signal directly acquired on the main signal line. In this way, characteristic values such as impedance and/or frequency response of the probe can be determined.