Abstract
This article explores an isolated precision signal chain reference design solution and its profound impact on preserving accuracy and enhancing reliability in data acquisition applications.
Introduction
The digital age has shifted the paradigm in bringing intelligence to the edge to solve novel and complex challenges. Right at this edge sits the core of this technology—data acquisitions (DAQ) systems. In the realm of data acquisition, preci- sion and reliability are paramount. To ensure the highest level of accuracy and integrity, the implementation of an isolated precision signal chain has emerged as a critical component.
Understanding Isolated Precision Signal Chain
An isolated precision signal chain refers to a system or circuitry designed to achieve precise and accurate signal acquisition and processing while maintaining electrical isolation from the surrounding environment. Isolation is often included as part of the series of signal conditioning stages for two main purposes: safety and data integrity. The isolation similarly includes the following advantages:
- Noise and interference reduction: By employing isolation techniques such as galvanic isolation, which uses transformers or optocouplers, the signal chain can eliminate common-mode voltage variations, ground loops, and electromagnetic interference (EMI). This isolation prevents external noise sources from corrupting the acquired signal, ensuring cleaner and more accurate measurements.
- Ground loop elimination: Ground loops can introduce voltage differentials that distort the measured signal. Isolation techniques break the ground loop path, effectively removing the interference caused by varying ground potentials, thereby improving measurement accuracy.
- Safety and protection: Isolation barriers provide electrical safety by preventing hazardous voltage spikes, transients, or surges from reaching sensitive measurement components. This protects both the measurement circuitry and the connected devices, ensuring safe and reliable operation. Aside from circuit protection, isolation also eliminates the electrical hazards for both end users and designers working on the system.
Additionally, an isolated precision signal chain consists of a series of components and techniques that work together to ensure accurate measurement and data integrity. The key components of an isolated precision signal chain typically include precision amplifiers, isolation barriers, filtering elements, and high resolution analog-to-digital converters (ADCs). These components work in tandem to eliminate noise, minimize interference, and provide accurate signal representa- tion. An example of an isolated precision signal chain utilizing these key com- ponents is shown in Figure 1. This precision platform is a single-channel, fully isolated, low latency data acquisition system. This solution combines PGIA signal conditioning, digital, and power isolation within a compact board. The succeeding sections will discuss each of the blocks in detail, including their corresponding performance and their advantages as compared to the nonisolated equivalent.
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