Switched-Capacitor Isolation Amplifier for Analog Signal Transfer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing isolation amplifiers require complex and expensive power supply systems for galvanic isolation, often involving digital conversion of analog signals, which complicates the circuitry and increases costs, while optical isolation products may not provide desirable offset, linearity, and drift characteristics.
Innovation Solution
The use of switched capacitors to galvanically isolate and amplify analog signals without the need for an isolated power supply, employing a monolithic integrated circuit with high and low voltage domain switches synchronized to transfer differential voltage signals across capacitors, thereby eliminating the need for analog-to-digital conversion and providing a self-contained power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional isolation amplifiers use digital conversion (ADC/DAC) with transformers for galvanic isolation, then isolation capability is achieved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent extracts and eliminates the complex digital conversion stage (ADC/DAC) and isolated power supply from the isolation amplifier architecture. By using a capacitor-coupled differential architecture, the invention achieves galvanic isolation through direct capacitive coupling rather than through digital conversion and transformation, thereby removing unnecessary complex components while maintaining isolation capability.
Solution Approach 2:
The patent introduces capacitors as intermediary elements to achieve galvanic isolation. The capacitors couple the input and output stages while blocking DC isolation, allowing AC signal transmission without direct electrical connection. This intermediary approach replaces the need for complex digital conversion and transformer-based isolation, simplifying the overall circuit architecture.
2Reliability
If optical isolation products use optocouplers for galvanic isolation, then isolation is achieved, but offset, linearity, and drift characteristics deteriorate
Solution Approach 1:
The patent replaces the optical isolation mechanism (optocouplers) with an electrical capacitive coupling mechanism. By using capacitors to achieve galvanic isolation, the invention maintains signal integrity and electrical characteristics that are superior to optical isolation, thereby improving offset, linearity, and drift characteristics while still achieving galvanic isolation.
3Adaptability or versatility
If isolation amplifiers integrate input power supply into single package, then device integration is improved, but power circuitry complexity and cost increase due to isolation across digital barrier
Solution Approach 1:
The patent extracts and eliminates the need for isolated power supply integration by using a capacitor-coupled differential architecture. The single-supply operation enabled by this architecture removes the requirement for complex isolated power circuitry, allowing simple single-package integration without the burden of isolation-across-digital-barrier power management.
Solution Approach 2:
The patent creates a universal isolation amplifier architecture that can operate from a single power supply while maintaining galvanic isolation capability. The capacitor-coupled differential architecture serves multiple functions: achieving galvanic isolation, enabling single-supply operation, and simplifying power circuitry, thereby providing multi-functionality that reduces overall system complexity.
4Reliability
If analog-to-digital conversion is used for isolation, then galvanic isolation is achieved, but loss of information and increased device complexity occur
Solution Approach 1:
The patent replaces the analog-to-digital conversion mechanism with direct capacitive coupling. By maintaining the signal in analog form throughout the isolation barrier using capacitor-coupled differential architecture, the invention eliminates information loss associated with digital conversion while achieving galvanic isolation, thereby preserving signal fidelity.
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 solution achieves accurate and economical galvanic isolation of analog signals, enabling efficient current sensing in high voltage systems up to ±1000 volts with improved linearity and reduced cost, as it maintains the signal in an analog form without the need for digital conversion or external power supply, thus providing a compact and efficient isolation amplifier.
Implementation Method 1
a plurality of capacitors having a plurality of input plates respectively connected to the plurality of switches of the input stage and a plurality of output plates respectively connected to the plurality of switches of the output stage
Data Source
AI summary
Integrated circuits and methods to provide an operative coupling comprising an input stage and an output stage between an analog input and an analog output; synchronously operate a plurality of high voltage domain switches of the input stage and a plurality of low voltage domain switches of the output stage at a frequency to galvanically isolate the input stage from the output stage across a plurality of capacitors having a plurality of input plates respectively connected to the switches of the input and output stages; supply an analog input signal to the input stage; transfer a differential voltage signal component within a range of a common mode voltage supply from the high voltage domain of the input stage to the low voltage domain of the output stage; differentially amplify the low voltage domain differential voltage signal component; and output an analog output signal.