Multi-Path Optical Probing for Isolated Full-Bandwidth Signals
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Solution Overview
Problem
Conventional optical signal transmission systems suffer from limited bandwidth, distortion due to offset misalignment, and nonlinear attenuation, compromising signal fidelity in high-speed differential measurements under high common-mode voltage conditions.
Innovation Solution
A signal transmission system with multiple frequency-optimized paths for analog signal modulation and demodulation, using techniques like frequency and amplitude modulation, and optical fibers for galvanic isolation, with delay equalization and offset management to ensure high-fidelity signal acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optical signal transmission systems are used for galvanic isolation, then common-mode rejection is improved, but bandwidth is limited and signal fidelity deteriorates due to distortion and nonlinear attenuation
Solution Approach 1:
The optical transmission system is segmented into multiple independent channels, each optimized for specific frequency ranges. The input signal is divided into multiple frequency bands that are transmitted through separate optical paths with different modulation schemes, allowing each channel to operate within its optimal performance range while maintaining overall signal fidelity and achieving galvanic isolation.
Solution Approach 2:
The system dynamically adapts modulation parameters such as frequency deviation, amplitude, and phase based on the input signal characteristics and channel conditions. This dynamic adjustment allows the system to optimize signal transmission for different frequency components and maintain high measurement precision across varying signal conditions while preserving common-mode rejection capabilities.
2Speed
If high-speed switching measurements are performed under high common-mode voltage conditions, then switching performance is improved, but signal integrity is obscured and measurement accuracy deteriorates
Solution Approach 1:
An optical intermediary system is introduced between the high-speed switching circuit under test and the measurement instrument. This optical mediator provides galvanic isolation that blocks common-mode voltage transients and ground loops, allowing high-speed switching signals to be transmitted without contamination from common-mode interference, thereby preserving both switching speed characteristics and signal integrity.
Solution Approach 2:
The electrical signal transmission path is replaced with an optical transmission system. By converting electrical signals to optical signals for transmission and then back to electrical signals, the system eliminates direct electrical connections that are susceptible to common-mode interference, enabling accurate measurement of high-speed switching waveforms even under high common-mode voltage conditions.
3Device complexity
If single-path optical transmission is used for simplicity, then device complexity is reduced, but bandwidth and signal fidelity are compromised
Solution Approach 1:
The transmission system is divided into multiple parallel optical paths, each handling specific frequency bands or signal components. This segmentation allows each path to be optimized for its designated function, collectively achieving broad bandwidth and high signal fidelity while maintaining manageable system complexity through modular architecture.
Solution Approach 2:
The multi-path optical transmission system is designed with universal interfaces and standardized modulation/demodulation modules that can handle different signal types and frequency ranges. This multi-functionality allows the system to process diverse measurement signals through the same architectural framework, achieving high bandwidth utilization without proportionally increasing operational complexity.
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 system provides accurate, high-fidelity signal acquisition with broad bandwidth and robust common-mode rejection, suitable for characterizing high-speed power electronics and wide-bandgap semiconductors.
Implementation Method 1
an optical transmitter, configured to convert the electrical-analog signal to an optical-analog signal
Implementation Method 2
transmitted across galvanically isolated links such as optical fibers
Implementation Method 3
an optical receiver, configured to convert the optical-analog signal back into an electrical-analog signal
Data Source
AI summary
An optical probing system transmits high-fidelity analog signals from a device under test (DUT) to a measurement instrument. The system receives a differential input signal and separates it into a high-frequency (HF) component and a low-frequency (LF) component. Each component is independently modulated using distinct analog modulation techniques and transmitted over separate optical fibers. The architecture maintains galvanic isolation between the input and output devices and enables independent transmission of signal portions optimized for bandwidth and accuracy. The signals are demodulated, delay-aligned, and recombined in the analog domain to produce a reconstructed full-bandwidth output.