Data acquisition T
he 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 acquisition (DAQ) systems. In the realm of data acquisition, precision 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 analogue-to-digital converters (ADCs). These components work in tandem to eliminate noise, minimise interference, and provide accurate signal representation. An example of an isolated precision signal chain utilising these
58
Figure 1. Simplified block diagram of a single-channel, fully isolated, low latency data acquisition system, ADSKPMB10-EV-FMCZ.
key components 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 non-isolated equivalent.
DATA AND POWER ISOLATION The Pmod-to-FMC interposer board houses digital isolators, regulators, and a transformer to implement
galvanic isolation. Galvanic isolation is a design technique that separates electrical circuits to eliminate stray currents. Signals can pass between galvanically isolated circuits, but stray currents, such as differences in ground potential or currents induced by AC power, are blocked. First, data isolation is enabled by the ADuM152N and ADuM120N 3kVrms digital isolators. These digital isolators exhibit high common-mode transient immunity (CMTI) and are highly robust to radiated and conducted noise while providing low propagation delay and low dynamic
PRESERVING ACCURACY AND ENHANCING RELIABILITY IN DATA ACQUISITIONS WITH ISOLATED PRECISION SIGNAL CHAINS
By Lloben Paculanan, Chelsea Faye Aure and Jan Michael Gonzales, Analog Devices
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.
Figure 2. Reference platform isolated power circuit block diagram. September 2025 Instrumentation Monthly
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72
