Capacitive Data Transmission Over Galvanic Isolation Barrier
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Solution Overview
Problem
Galvanic isolation barriers in electronic devices often require significant chip space and complexity due to the need for differential signal communication, which can be prone to noise and glitches from sudden reference voltage changes.
Innovation Solution
A single capacitor configuration across the galvanic isolation barrier is used to transmit single-ended signals, accompanied by high-pass and low-pass filters in the receiving domain to generate a differential signal, reducing chip space and complexity while mitigating noise and glitches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If differential signal communication is used across the galvanic isolation barrier, then noise and glitches are compensated for, but chip space and device complexity increase significantly
Solution Approach 1:
The patent extracts and eliminates the differential signaling requirement, using a single-ended signal transmission approach instead. This removes the need for two capacitors and differential receiver circuitry, significantly reducing chip space and device complexity while maintaining galvanic isolation benefits
Solution Approach 2:
The patent introduces a single capacitor as an intermediary element that couples the single-ended signal across the galvanic isolation barrier. This simple intermediary structure replaces the complex differential signaling path, achieving noise immunity through the capacitor's inherent properties rather than through differential cancellation
2Object-affected harmful factors
If two capacitors are used for differential signal communication, then noise compensation is achieved, but chip space consumption increases substantially
Solution Approach 1:
The patent merges the functions of two capacitors into a single capacitor. The single capacitor performs both signal coupling and noise filtering functions that traditionally required two separate capacitors in a differential configuration, thereby halving the chip space requirement for the isolation barrier components
Solution Approach 2:
The patent uses a single capacitor configuration that effectively copies or replicates the noise immunity functionality of differential signaling without requiring the physical duplication of components. The single capacitor's impedance characteristics provide equivalent noise rejection to the more complex differential pair
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
This approach allows for effective communication across the galvanic isolation barrier with less chip space and lower complexity compared to traditional differential signal methods, while minimizing noise and glitches caused by reference voltage changes.
Implementation Method 1
a capacitor arranged across the galvanic isolation barrier, where the capacitor is configured to communicate a single-ended signal from the first voltage domain to the second voltage domain
Implementation Method 2
a high-pass filter arranged in the second voltage domain and configured to receive the single-ended signal from the capacitor
Implementation Method 3
a low-pass filter arranged in the second voltage domain and coupled between the high-pass filter and a low-impedance node, and the low-pass filter is configured to generate a differential signal
Data Source
AI summary
In some examples, a device includes a capacitor arranged across the galvanic isolation barrier, where the capacitor is configured to communicate a single-ended signal from a first voltage domain to a second voltage domain. The device also includes a high-pass filter arranged in the second voltage domain and configured to receive the single-ended signal from the capacitor. The device further includes a low-pass filter arranged in the second voltage domain and coupled between the high-pass filter and a low-impedance node. The high-pass filter is coupled between the capacitor, the low-pass filter, and the low-impedance node, and the low-pass filter is configured to generate a differential signal.