PCB Isolation Domain for Common Mode Noise Control
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Solution Overview
Problem
Existing noise control methods in printed circuit boards are inadequate in preventing electromagnetic noise interference between controllers and gate drivers, as physical separation does not fully mitigate signal noise, especially with high-speed voltage and current transitions in switching power converters.
Innovation Solution
A system with an isolation domain on the printed circuit board, defined by two moats, that splits gate drive signals into differential pairs and power signals into isolated ground reference and power signals, using stacked traces to prevent common mode noise, and includes two isolation couplings to ensure noise immunity across the board.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If physical separation is used to prevent noise interference between controller and gate driver, then noise interference is reduced, but signal transfer quality deteriorates due to coupling onto gate control lines
Solution Approach 1:
An isolation domain with isolation couplings is introduced as an intermediary between the controller and gate driver. This isolation domain includes first and second isolation couplings that electrically isolate the controller from the gate driver while still allowing signal transfer, thereby preventing noise interference without compromising signal quality.
Solution Approach 2:
The PCB is segmented into distinct domains: a controller domain, a switching domain, and an isolation domain. The isolation domain acts as a buffer zone with isolation couplings that separate the low-voltage controller side from the high-voltage switching side, preventing noise coupling while maintaining functional connectivity.
2Object-affected harmful factors
If physical separation distance is increased between controller and gate driver, then noise interference is reduced, but device complexity increases
Solution Approach 1:
The isolation domain serves multiple functions simultaneously: it provides noise isolation, enables signal transfer between domains, and establishes distinct voltage reference domains. This multi-functionality reduces the need for additional separate components or complex routing arrangements.
3Object-affected harmful factors
If isolation domain with moats is implemented, then common mode noise is prevented, but manufacturing complexity increases
Solution Approach 1:
The isolation couplings change the electrical parameters (impedance, voltage reference) at the boundaries of the isolation domain. This parameter transformation allows the isolation domain to block common mode noise while maintaining signal integrity through controlled impedance transitions.
Data Source
AI summary
In accordance with at least one aspect of this disclosure, a system can include, a printed circuit board (PCB), a controller on the PCB configured to output a gate drive signal to one or more gate drivers 106 to drive a gate 108 of a switch (e.g., a transistor), and an isolation domain. The isolation domain can be defined in the PCB between the controller and the one or more gate drivers. More specifically, the isolation domain can begin at a first moat and end at a second moat, defined between the controller and the one or more gate drivers. The isolation domain can be configured to prevent common mode noise in the gate drive signal.