Rectifier Signal Reconstruction Across Noisy Isolation Barriers
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Solution Overview
Problem
Common mode voltages can affect the performance of isolation barriers, leading to signal loss and inhibiting the ability of a second isolated circuit to determine whether a signal has been generated by a first circuit.
Innovation Solution
An electronic device with a first circuit, a second circuit, and an isolation circuit, where the second circuit includes a rectifier circuit and a signal detector circuit that integrates rectifier current and voltage signals to generate a summed voltage signal, compares it to a threshold, and selectively enables or disables an actuator circuit based on the comparison, mitigating signal loss due to common mode noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an isolation circuit is used to transfer signals and power between circuits at different voltage levels, then voltage level isolation is achieved, but common mode voltages cause signal loss and detection failure
Solution Approach 1:
The patent introduces a rectifier circuit as an intermediary component between the isolation barrier and the signal detector. This rectifier circuit converts the differential signal from the isolation barrier into a rectified signal that can be reliably detected despite common mode voltage interference. The rectifier acts as a mediator that transforms the signal into a form that is immune to the harmful common mode voltages, thereby resolving the contradiction between maintaining isolation and achieving reliable signal detection.
Solution Approach 2:
The patent changes the parameter domain of the signal by rectifying it. Instead of detecting the original differential voltage signal directly, the system rectifies the signal to change its parameter characteristics. This parameter transformation allows the signal to be detected in a different domain where common mode voltages do not cause the same interference problems, thus resolving the detection reliability issue while maintaining isolation.
2Reliability
If the second circuit directly detects the signal from the isolation circuit output, then circuit complexity is minimized, but signal detection fails under common mode voltage conditions
Solution Approach 1:
A rectifier circuit is introduced as an intermediary component between the isolation barrier output and the signal detector. This intermediary rectifier circuit transforms the differential signal into a rectified signal that can be reliably detected. While this adds some circuit complexity, it dramatically improves signal detection accuracy under common mode voltage conditions, resolving the contradiction between detection reliability and circuit simplicity.
3Device complexity
If signal and power are transferred through the same isolation circuit, then component count is reduced, but common mode voltages affect both signal integrity and power quality
Solution Approach 1:
The patent segments the signal processing function from the power transfer function. The rectifier circuit is specifically configured to handle signal rectification and detection, while the isolation barrier handles both signal and power transfer. This segmentation allows the signal detection path to be optimized for immunity to common mode voltages while the power path maintains its isolation function, resolving the contradiction between component simplicity and transfer reliability.
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 effectively detects and reconstructs the presence of a signal across an isolation barrier in the presence of common mode noise, ensuring reliable signal detection and transfer of power, independent of common mode interference.
Implementation Method 1
integrating a rectifier current of a rectifier diode or a rectifier transistor in a rectifier circuit to generate an integrator voltage signal
Implementation Method 2
comparing the summed voltage signal to a threshold voltage to generate a comparator output signal
Data Source
AI summary
An electronic device has a first circuit, a second circuit, and an isolation circuit, the isolation circuit having an input and an output, the first circuit including a signal generator having an output, the output of the signal generator coupled to the input of the isolation circuit. The second circuit includes a rectifier circuit and a signal detector circuit, the rectifier circuit having a rectifier input coupled to the output of the isolation circuit, and the signal detector circuit having an input coupled to the output of the isolation circuit.