Design and Validation of a Movable Pin-Contact Miniature Current Probe for Chip-Level EMI Noise Measurement

This study originates from IEC 61967-4 standards for measuring electromagnetic emissions at the chip level. The measuring probe with fixed SMA connector in IEC 61967-4 method was improved with a proposed radio frequency (RF) current probe by featuring a semi-rigid coaxial cable to be capable of making movable measurements, and thus enhancing the flexible probing usage. To evaluate and validate the effectivity of the proposed probe, we have referred to the standard designs provided in IEC 61967-1 to manufacture a four-layer digital circuit board for controlling the screen of an on-board navigational system for automobiles. The results of circuit board EMI noise frequency and level readings measured with the proposed probe was also compared with two other measurement methods, namely magnetic field probe and TEM cells method. The measured data were cross-referenced in order to ensure that the proposed movable current probe described in this paper obtained consistent EMI noise frequency and level readings compared to the other two methods. The results show the capability of the improved movable contact-type current probe in effective identification of sources of noise at the chip-level during IC design phases, and thus helps for root cause analysis of EMI noises from chip-level to solve promptly during the process of EMC design for product optimization and analysis.