Radiation Emission Source Localization by Magnetic Near-Field Mapping Along the Surface of a Large-Scale IC With BGA Package

Near-field mapping along the surface of an integrated circuit (IC) could reveal the radiated emission source inside by collecting the radiated electromagnetic field. In this article, the radiated emission source localization is first illustrated in a microstrip line model by analyzing the relationship between the physical position of the line and the hot spots of the electromagnetic field distribution along the line surface. The hot spot in each magnetic field distribution does not necessarily correspond to the physical position of the emission source due to the ground plane below. Furthermore, by analogy with the microstrip line model, the localization analysis is applied to a large-scale IC [field-programmable gate array (FPGA)] in a ball grid array package. For the demonstration, four operation states of the FPGA are designed with four general-purpose input–output (GPIO) pins outputting waveforms of different frequencies. By activating the sources in different operation states, it is found that the activated GPIO pins (as emission sources) can be located well by comprehensively analyzing the emission patterns of different components. The experimental results would be instructive to improve the understanding of IC near-field electromagnetic patterns and reasonable to localize an emission source.

I. Introduction

Near-field mapping of the electromagnetic (EM) radiation along the surface of an integrated circuit (IC) is popular in current days due to the assessment application for the EM radiation emission of the IC component. Such a near-field scanning method [1], [2] has been standardized for the purpose of radiated EM emission assessment in IEC 61967-3 [3]. To perform a near-field mapping of the EM field along the surface of an IC, an electric field probe and a magnetic field probe are needed. By scanning along the surface of the tested IC at each position, the radiated EM emission spectrums are collected. After the scanning, the intended emission is extracted with an emission pattern at different frequencies. Usually, there are lots of existing emission patterns for an IC under different frequencies. With the development of the near-field mapping method, the near-field scanning method has been applied from the microstrip line [4], [5] to the IC components in kinds of packages, such as simple dual in-line package [6], surface mount device [7], quad flat package [8], and now ball grid array (BGA) [9]. In 2018, the device under test (DUT) was expanded to the system-in-package module [10].