Capacitive Isolator Bridge Board for Galvanic Isolation
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Solution Overview
Problem
Existing signal isolators face challenges in maintaining digital and analog signal integrity across magnetically coupled galvanic isolation barriers, particularly in achieving wide bandwidth and minimizing propagation delay for digital signals, and linearity for analog signals, while also requiring efficient power management across the isolation boundary.
Innovation Solution
A multilayer printed circuit board (PCB) bridge board with conductive shields and transformers, where A-side and B-side windings are formed in separate conductive layers, providing galvanic isolation and magnetic field coupling, and powered by energy transferred across the transformer, enabling efficient signal transfer and power distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnetically coupled galvanic isolation barrier is used to provide safety and minimize disturbances, then galvanic isolation is achieved, but bandwidth is reduced and propagation delay increases for digital signals
Solution Approach 1:
The patent replaces traditional magnetic coupling mechanisms with electric field-based capacitive coupling. The isolator uses a capacitive coupling structure where electric fields transfer signals across the isolation boundary, eliminating the bandwidth limitations and propagation delays inherent in magnetic transformer coupling while maintaining galvanic isolation.
Solution Approach 2:
The patent changes the fundamental operating parameters by using high-frequency electric field coupling instead of low-frequency magnetic coupling. The capacitive isolator operates at frequencies where electric field transfer is highly efficient, achieving wide bandwidth and low propagation delay while maintaining the isolation barrier.
2Reliability
If traditional transformer coupling is used for signal isolation, then galvanic isolation is provided, but power management efficiency deteriorates
Solution Approach 1:
The patent replaces magnetic transformer-based power transfer with direct electric field coupling. The capacitive structure enables more efficient power management by allowing bidirectional energy transfer with lower losses, eliminating the need for complex transformer-based power isolation schemes.
3Speed
If wide bandwidth is achieved for digital signal transfer, then high frequency signal integrity is improved, but propagation delay increases
Solution Approach 1:
The patent substitutes magnetic field propagation with direct electric field coupling. Electric fields propagate instantaneously across the isolation boundary compared to magnetic field induction, achieving wide bandwidth without the propagation delays characteristic of transformer-based isolators.
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 ensures high-frequency digital signal integrity and linearity in analog signal transfer with reduced propagation delay and efficient power management, effectively addressing the challenges of signal isolation and power distribution across the isolation boundary.
Implementation Method 1
each A-side and B-side winding being formed in a respective conductive layer of the bridge board and located in a region providing space for a magnetic field coupling the A-side and B-side windings
Implementation Method 2
The bridge board includes at least one conductive shield
Data Source
AI summary
A signal isolator apparatus includes a first substrate for supporting input circuitry including a high frequency oscillator circuit for receiving an input signal, a second substrate for supporting output circuitry including a detector circuit for providing an output signal; and a third substrate having parallel conductive layers separated by insulation. The third substrate has an upper conductive shield formed in a second conductive layer and a lower conductive shield formed in a fifth conductive layer. A transformer is formed between the upper and lower conductive shields and includes a primary winding formed in a third conductive layer and a secondary winding formed in a fourth conductive layer. The oscillator circuit is connected to the primary winding and adapted to excite the primary winding at a first frequency in response to the input signal, and the detector circuit is connected to the secondary winding and adapted to selectively sense the first frequency and provide the output signal. The third substrate is arranged to form a bridge connection between the first and second substrates.