Differential Signal Bias Balancing to Reduce Mode Conversion Loss
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Solution Overview
Problem
The increase in mode conversion loss due to variations in electrical characteristics of electronic components caused by different bias voltages applied to the P and N sides of differential signal wirings, leading to deteriorated electromagnetic compatibility (EMC) performance in high-frequency signal transmission.
Innovation Solution
A signal transmission device with an output voltage determination unit and power supply circuit that adjusts the applied voltages to the differential signal wirings, using components like electrostatic protection elements and filters, to maintain electrical balance and reduce mode conversion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different bias voltages are applied to P and N sides to meet power consumption requirements, then power supply flexibility is improved, but mode conversion loss increases and EMC performance deteriorates
Solution Approach 1:
The patent applies equipotentiality by introducing a reference potential circuit that provides a common reference potential to both P-side and N-side electrostatic protection elements. This ensures that both sides operate at the same potential level, preventing mode conversion loss and maintaining differential balance even when different bias voltages are applied to meet power consumption requirements.
Solution Approach 2:
The patent uses a reference potential circuit as an intermediary between the P-side and N-side power supply systems. This intermediary circuit provides a common reference potential that mediates the interaction between different bias voltages, preventing direct potential differences from causing mode conversion while still allowing flexible power supply configuration.
2Object-affected harmful factors
If electrostatic protection elements are mounted on differential signal wirings, then noise resistance is improved, but electrical characteristic imbalance occurs due to parasitic capacitance variation with DC bias
Solution Approach 1:
The patent applies equipotentiality by ensuring that both electrostatic protection elements operate at the same reference potential through the reference potential circuit. This eliminates potential-induced parasitic capacitance variations, maintaining electrical characteristic balance while preserving noise resistance benefits.
Solution Approach 2:
The patent changes the operating condition parameter (reference potential) of the electrostatic protection elements by introducing a common reference potential circuit. This parameter change ensures that both elements operate under identical electrical conditions, preventing imbalance caused by potential differences while maintaining their noise protection function.
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 suppresses the increase in mode conversion loss, enhancing EMC performance by maintaining electrical symmetry in differential transmission paths and reducing noise resistance.
Implementation Method 1
a filter component that is arranged between the power supply circuit and each of the first signal wiring and the second signal wiring
Implementation Method 2
In an electrostatic protection element mounted on each of the signal wirings on the P side and the N side, a parasitic capacitance component may decrease according to the magnitude of the DC bias
Data Source
AI summary
A signal transmission device according to one aspect of the present invention is a signal transmission device that performs differential transmission, and includes an information processing circuit that performs processing of various types of information, and a power supply circuit that includes a voltage output circuit outputting a first applied voltage to a first signal wiring and outputting a second applied voltage to a second signal wiring. The information processing circuit includes an output voltage determination unit that determines an instruction value of at least one of the first applied voltage or the second applied voltage applied by the power supply circuit and that sends the determined instruction value to the power supply circuit. The power supply circuit has an output voltage adjustment function of adjusting a parameter of the voltage output circuit such that the first applied voltage or the second applied voltage reflecting the received instruction value are output to the first signal wiring and the second signal wiring.