Analog Signal Isolation via Microwave Coupling for Floating Measurements
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Solution Overview
Problem
Test and measurement systems face challenges in isolating floating signals from ground-referenced signals, leading to erroneous data and improper scaling due to direct connections, which can result in injury or equipment damage.
Innovation Solution
An electromagnetically coupled analog isolator mechanism using a microwave structure with an upconverter and downconverter to modulate signals across an isolation barrier, preventing sub-microwave signals from crossing while allowing microwave frequency signals to pass, thus maintaining isolation and enabling accurate measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a direct connection is made between the DUT and the oscilloscope, then the measurement system can directly measure voltages, but the floating signals become connected to ground resulting in erroneous data and improper scaling
Solution Approach 1:
An isolation barrier is introduced as an intermediary component between the DUT and the oscilloscope. This barrier includes a transformer that magnetically couples the floating signal from the DUT to the ground-referenced oscilloscope without providing a direct galvanic connection. The transformer acts as a mediator that transfers the signal while maintaining electrical isolation, thereby preventing ground loops and measurement errors while preserving the ability to measure voltages accurately.
2Reliability
If an isolation barrier is introduced to prevent direct connection, then signal isolation is achieved, but the system complexity increases
Solution Approach 1:
A transformer is used as the isolation barrier, which is a relatively simple and well-understood component. The transformer provides galvanic isolation through magnetic coupling, blocking DC and low-frequency noise while passing AC signals. This approach achieves reliable signal isolation without introducing overly complex circuitry, as transformers are standard components in measurement systems.
Solution Approach 2:
The patent replaces direct electrical (galvanic) connection with magnetic coupling. Instead of using a direct wire connection that provides both signal transfer and ground reference, the system uses a transformer to transfer signals magnetically. This substitution provides isolation while maintaining signal integrity, and the transformer is a mature, reliable component that does not significantly increase system complexity.
3Productivity
If floating signals are measured without isolation, then the measurement system can capture voltage differences, but the large base voltage value obfuscates fine differential measurements
Solution Approach 1:
The transformer serves as an intermediary that transfers only the AC component of the signal from the floating DUT to the ground-referenced oscilloscope. By blocking DC and low-frequency components, the transformer allows the oscilloscope to focus on measuring the differential AC signal without being overwhelmed by large DC voltage offsets. This enables fine differential measurements to be captured with high resolution.
Solution Approach 2:
The isolation barrier transforms the signal parameters by blocking DC components and low-frequency noise while passing AC signals. This parameter filtering allows the measurement system to operate in an optimal range where fine differential voltage changes can be detected with high precision, rather than being swamped by large DC voltage levels.
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 solution effectively isolates floating signals from ground-referenced test systems, preventing damage and ensuring accurate data acquisition by maintaining signal integrity and safety.
Implementation Method 1
a microwave structure to transmit the microwave frequency analog signal across the isolation barrier via electromagnetic coupling
Data Source
AI summary
Disclosed is a signal isolating test instrument, such as an electronics test probe. The instrument includes an input to receive a floating analog signal. An upconverter is employed to modulate the floating analog signal to a microwave frequency analog signal. An isolation barrier in the instrument prevents coupling of the floating analog signal to an earth ground. The instrument employs a microwave structure to transmit the microwave frequency analog signal across the isolation barrier via electromagnetic coupling. A downconverter is then employed to demodulate the microwave frequency analog signal to obtain a ground referenced test signal corresponding to the floating analog signal.