Common-Mode Noise Filter With Equalizer for Differential Lines
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Solution Overview
Problem
High-speed digital circuits face issues with common-mode noise due to discontinuous structures and limited conductivity, leading to electromagnetic interference and interbit interference that degrade signal quality and logic circuit performance.
Innovation Solution
A digital electronic device with a grounded metal portion, differential-mode reference metal portions, and equalizers that are electromagnetically coupled to differential signal lines, comprising parallel RC circuits or series resistor-inductor circuits to suppress common-mode noise and improve the eye diagram.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If differential transmission lines are used to transmit differential signals, then crosstalk effect and electromagnetic radiation are reduced, but common-mode noise is generated due to discontinuous structures and asymmetric signal characteristics
Solution Approach 1:
An equalizer circuit is introduced as an intermediary component between the differential transmission line and the load. The equalizer compensates for signal distortion and suppresses common-mode noise by equalizing the signal characteristics, thereby resolving the contradiction between reducing crosstalk and preventing common-mode noise generation
Solution Approach 2:
The patent modifies the electrical parameters of the transmission system by introducing an equalizer that adjusts signal amplitude and phase characteristics. This parameter change compensates for the effects of discontinuous structures and asymmetric signaling, reducing common-mode noise while maintaining the benefits of differential transmission
2Area of stationary object
If discontinuous structures such as bends and through holes are introduced to reduce area, then layout flexibility is improved, but common-mode noise increases
Solution Approach 1:
The equalizer serves as a mediator that compensates for the adverse effects of discontinuous structures. By equalizing signal characteristics and suppressing common-mode components, it allows the use of area-efficient layout techniques while maintaining signal integrity and minimizing noise
3Ease of manufacture
If differential transmission line with limited conductivity is used, then manufacturing is simplified, but frequency dependent transmission line loss occurs causing interbit interference
Solution Approach 1:
The equalizer acts as an intermediary that compensates for frequency-dependent losses in the differential transmission line. It restores signal quality by equalizing attenuated frequency components, thereby maintaining reliable signal transmission despite the limited conductivity of practical transmission lines
Solution Approach 2:
The equalizer implements a feedback mechanism where signal characteristics are analyzed and compensated for frequency-dependent losses. This feedback approach restores eye diagram quality and reduces interbit interference while maintaining the simplicity of standard transmission line manufacturing
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 device effectively reduces common-mode noise and enhances signal quality by improving the eye diagram and electrostatic discharge protection, while maintaining differential-mode performance.
Implementation Method 1
an equalizer electrically connected to the pair of differential signal lines
Implementation Method 2
a grounded metal portion comprising a first metal plate electrically connected to ground
Data Source
AI summary
This invention provides a digital electronic device comprising: a grounded metal portion comprising a first metal plate electrically connected to ground and a first substrate disposed on the first metal plate; at least one layer of differential-mode reference metal portion comprising a second substrate and a second metal plate electrically connected to the first metal plate by at least one conductive structure; a pair of differential signal lines at least partially disposed on the second substrate of the at least one layer of differential-mode reference metal portion and electromagnetically coupled to the second metal plate of the at least one layer of differential-mode reference metal portion; and an equalizer electrically connected to the pair of differential signal lines.