A Research On EMC And Si Of PCB Of Medical Ultrasonic Flowmeter

With the rapid development of science and technology, medical electronic equipments’ operating frequency is getting higher and higher, the functional requirements are tending to be more and more and intelligent, the product model is being more and more miniaturized, printed circuit board layers is being closer and closer, which is closely followed by a series of Electromagnetic Compatibility issues, such as electromagnetic interference, Signal Integrity problems and so on. Therefore, a deep research of PCB EMC is urgent and necessary to ensure electronic medical product works safely and productive.This paper carried on a study of EMC and SI of medical ultrasonic flowmeter’s Printed Circuit Board, with a combination of relative theory of EMC and a specific software Ansys, which is pretty suit for simulations on PCB EMC, SI (including PI).Firstly, this paper introduces the relative theory of EMC and SI, then a simulation of the rsearching target as if medical ultrasonic flowmeter PCB is carried out with SI wave software in both time and frequency domains. The simulation on critical signals is carried out with the combination of S parameter and IBIS model;A board level simulation on EMC is also carried but in both near and far field with the reference of USA FCC Standard on EMI; An analization of power and frequency impedance characteristic is necessary to ensure that the signal runs stably on the reference plane of PCB. The logic volt in low level driver IBIS model is valid and plate simulation signal integrity is very good according to the results of the simulation; The PCB successfully satisfys the requirements of EMC and EMI as its power supply has less impedance than target and it has a good performance in other aspects. The simulation method is validated to be reasonable and effective with the successful pass of the EMC test under the medical industrial EMC standards.Finally, the method is applied to the PCB design of medical instruments and contributed an improvement to the products’reliability, and this is meaningful for medical product design and has certain significance to PCB design and it’s optimization in some degree.