Capacitive Communication Circuit for Voltage Isolation
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Solution Overview
Problem
Existing isolation circuits, such as optocouplers, are complex, costly, and sensitive to parameter variations, with high power consumption and low bandwidth, making it challenging to effectively isolate circuits operating at different voltages while protecting sensitive components from high voltages.
Innovation Solution
The use of capacitive signal communication methods involving the mixing of input signals with a carrier signal of a different frequency, allowing for effective isolation of circuits operating at different voltages through capacitive coupling, using pairs of capacitors to transmit and receive signals, and processing these signals to recover the original data without the need for analog filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optocouplers are used for galvanic isolation, then circuit isolation between different voltage domains is achieved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical/optical isolation system (optocouplers with light emitters and detectors) with an electrical system using capacitive coupling and signal mixing. The isolation function is achieved through capacitive blocks and frequency mixing circuits rather than optical components, reducing device complexity while maintaining galvanic isolation between different voltage domains
Solution Approach 2:
The patent changes the operating parameters by using frequency mixing to shift the data signal to a different frequency domain that can pass through the capacitive isolation barrier. By modulating the data signal with a carrier frequency and using differential mixing, the system achieves isolation while maintaining signal integrity without requiring complex optocoupler circuits
2Reliability
If optocouplers are used for galvanic isolation, then circuit isolation is achieved, but power consumption increases
Solution Approach 1:
The patent replaces the power-intensive optical system with a more energy-efficient electrical capacitive coupling system. The signal mixing and differential amplification approach consumes less power compared to driving light emitters and detecting signals through optical isolation, while achieving the same galvanic isolation effect
Solution Approach 2:
The patent uses periodic carrier signals for mixing and modulation to transfer data through the capacitive isolation barrier. This periodic action allows efficient signal coupling at specific frequencies while blocking other frequencies, achieving isolation with lower continuous power consumption compared to optocouplers that must continuously drive optical components
3Reliability
If optocouplers are used for galvanic isolation, then circuit isolation is achieved, but bandwidth is reduced
Solution Approach 1:
The patent changes the frequency parameters by modulating the data signal with a high-frequency carrier that can pass through the capacitive isolation barrier more effectively. This frequency transformation allows the system to achieve higher bandwidth compared to optocouplers, as the mixed frequency signals can be efficiently coupled through the capacitive blocks without the bandwidth limitations inherent in optical isolation systems
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 enables reliable and efficient isolation of circuits operating at different voltages, providing immunity to voltage transients and accurately recovering signals with minimal distortion, while reducing complexity and cost compared to traditional methods.
Implementation Method 1
capacitive signal communication methods involving the mixing of input signals with a carrier signal of a different frequency, allowing for effective isolation of circuits operating at different voltages through capacitive coupling
Implementation Method 2
An input signal is inverted, and both the inverted and non-inverted input signals are separately mixed (e.g., modulated) with a carrier signal having a frequency that is different than the frequency of the input signal
Data Source
AI summary
Data is communicated. In accordance with one or more example embodiments, a communications circuit communicates a digital data signal using a carrier signal having a frequency that is different than the frequency of the data signal. The communications circuit includes first and second sets of capacitors, a first circuit and a second circuit. The first circuit generates mixed data signals respectively mixed with the carrier signal and an inverse of the carrier signal, generates mixed inverted data signals respectively mixed with the carrier signal and an inverse of the carrier signal, provides the mixed data signals to the first set of capacitors, and provides the mixed inverted data signals to the second set of capacitors. The second circuit recovers the data signal from the mixed signals.