EMC and EMI Issues of Mixed Sensor - Control Boards for Medical Devices

With the growing use of mixed sensor-control boards in medical devices, electromagnetic compatibility (EMC) and electromagnetic interference (EMI) represent critical design challenges. For patient safety and device reliability, it is essential that these systems be immune to electromagnetic interference while maintaining the integrity of analog sensor signals. This work examines how an operational amplifier (OP AMP) circuit performs when high-frequency, high current switching signals are used in conjunction with different PWM duty cycles (0%, 20%, 40%, 80%, and 100^%) in a circuit for medical applications. The sensor impedances are 55 Ω, 0.96 kΩ, 9.83 kΩ. Four different PCB layouts are measured, and the results show design optimizations for improving EMC and reducing EMI. The conclusion of this study is that, before manufacturing, one needs to test several PCB designs, obtained with different design tools, for determining the best design.