MEDICAL
How to Meet Signal Integrity Challenges in Complex Medical Systems
High-speed digital technology is driving significant growth and advancements in complex medical systems, enabling improved performance, precision, and efficiency in many areas of healthcare delivery.
M
edical imaging systems play a crucial role in early detection and diagnosis across various areas of healthcare in orthopaedics, obstetrics, neurology, cardiology, and more. Surgical robots, hospital facilities robots, and telehealth systems are helping medical practitioners detect and diagnose medical conditions, enhancing care and extending lives. All these capabilities are enabled by high-speed digital signals, which means that the signal integrity in these systems is more important than ever.
Software innovations mean more high-speed digital hardware
Much of the value in these complex medical systems comes from the intelligence provided by software capabilities. Software used in medical devices processes and removes noise from images, produces 3D images, and trains and uses the neural networks that segment and classify images. For example, with MRIs, software algorithms can identify and highlight abnormalities like tumours or fractures, aiding radiologists in diagnosis.
The increased use of software enables the deployment of these complex medical systems in increasingly challenging applications, where reliability, speed, and low latency are essential for customer safety. This means that the digital hardware content of the devices must increase for faster data detection, acquisition, and signal processing, more and faster numeric processors and image shading processors, higher-speed memory, faster clock speeds, higher frame rates, faster interconnects, and advanced digital logic technologies and multi-level signalling schemes, including PAM4, PAM8, PAM16, and non-return-to-zero (NRZ) logic. In addition,
36 Figure 1: Simulation software analysing the effects of jitter on an eye diagram.
the increasing cybersecurity threat landscape, and regulatory requirements for the privacy of patient information are driving the use of digital hardware for data obfuscation, encryption, and validity checking.
More high-speed digital hardware drives test challenges
The increasing use of high-speed digital hardware drives complex test challenges for several reasons. The challenge of identifying small-bit error rates is particularly critical due to the potential impact on patient safety and the reliability of medical devices. Increased amounts of data mean that even small bit error rates will lead to more errors, as they can quickly accumulate over time. Medical diagnostics rely heavily on the accuracy of digital data transmitted between various components of the system. For example, in diagnostic imaging systems such as MRI or CT scanners, errors in data transmission or processing can distort images generated from extensive digital data, potentially causing misinterpretation
JUNE 2024 | ELECTRONICS FOR ENGINEERS or misdiagnosis.
The increased component density on printed circuit boards in high-speed digital hardware means that boards have less room for traces, which leads to more layers on the board and more test challenges. The tighter packing of components can lead to higher power densities and localised heating on the board. In medical devices, where precise temperature control is essential to ensure device functionality and patient safety, inadequate thermal management can lead to overheating, component failures, or thermal-induced performance degradation.
Several additional testing challenges arise with high-speed digital hardware Faster clock speeds and data rates reduce the tolerance of eye diagrams to signal noise and jitter. Multi-layer boards with more through-hole vias demand intricate manufacturing processes to enhance signal integrity. Additionally, heightened component density necessitates narrower traces, increasing the likelihood of unexpected opens compared to wider
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