EMI: Why Devices Radiate (original) (raw)
Related papers
2011
In high-speed circuits, the value of the inductance associated with a connection to a MLCC (Multi-Layer Ceramic Capacitor) is often more important than the nominal value of the capacitor. This paper has four main sections. The first section discusses the importance and the meaning of the connection inductance associated with MLCCs. The second section analyzes the effect of plate orientation in MLCCs. It demonstrates that vertically oriented plates have no more or less inductance than horizontally oriented plates when the overall dimensions of the plate stack are similar. The third section describes decoupling capacitance options at the various levels of a high-speed circuit (i.e. on-die, on-package and on-board). This section describes how the geometries at each level affect the relationship between connection inductance and resistance, and therefore determine the range of frequencies that decoupling at each level is likely to be effective. The fourth section describes innovative lo...
Accurate Models for Evaluating the Direct Conducted and Radiated Emissions from Integrated Circuits
Applied Sciences
This paper deals with the electromagnetic compatibility (EMC) issues related to the direct and radiated emissions from a high-speed integrated circuits (ICs). These emissions are evaluated here by means of circuital and electromagnetic models. As for the conducted emission, an equivalent circuit model is derived to describe the IC and the effect of its loads (package, printed circuit board, decaps, etc.), based on the Integrated Circuit Emission Model template (ICEM). As for the radiated emission, an electromagnetic model is proposed, based on the superposition of the fields generated in the far field region by the loop currents flowing into the IC and the package pins. A custom experimental setup is designed for validating the models. Specifically, for the radiated emission measurement, a custom test board is designed and realized, able to highlight the contribution of the direct emission from the IC, usually hidden by the indirect emission coming from the printed circuit board. Measurements of the package currents and of the far-field emitted fields are carried out, providing a satisfactory agreement with the model predictions.
Analysis of chip-level EMI using near-field magnetic scanning
2004
Abstract Integrated circuits (ICs) are often a significant source of radiated energy from electronic systems. Well designed ICs maintain good control of the currents that they generate. However, poorly designed ICs can drive high-frequency noise currents onto nominally low-frequency input and output pins. These currents can excite unintentional radiating structures on the printed circuit board, resulting in radiated emissions that are difficult or expensive to control.
EMI/EMC Analysis and Noise Reduction in High Frequency Devices
INTERNATIONAL JOURNAL OF ENGINEERING SCIENCES & RESEARCH TECHNOLOGY, 2014
Electromagnetic interference (EMI) or radio frequency interference (RFI) is a type of electric or electronic emission that can degrade the performance of electronic circuit.The effects of electromagnetic interference (EMI) is particularly troublesome for printed circuit board (PCB) designed for high frequency RF circuits. The components on a PCB may be digital and analog. Transmission lines connecting the two different sections are used to transmit signals back and forth. Unfortunately, as frequency increases and signals are enhanced, noise related to those frequencies is also enhanced, thus creating EMI and RFI. In terms of propagating path, it classifies into conducted EMI and radiated EMI. The conducted EMI results from that the radiated signal stick on the power line and hard to detect and recognize. Therefore, it is necessary to build the causes and effects methodology by way of the correct measurement to maintain the electromagnetic compatibility (EMC), to target the electromagnetic interference, and to detect radio frequency interference.Electronic systems are expected to operate normally within a given environment without internally or externally radiating excessive amounts of electromagnetic energy. In this state, they are called electromagnetically compatible (EMC). This paper presents a methodology to minimize radiated EMI by proper designing of PCB and conducted EMI by using EMI filter
Considerations for magnetic-field coupling resulting in radiated EMI
1998
Abstract Parasitic inductance in printed circuit board geometries can worsen the EMI performance and signal integrity of high-speed digital designs. Partial-inductance theory is a powerful tool for analyzing inductance issues in signal integrity. However, partial inductances may not adequately model magnetic flux coupling to EMI antennas because the EMI antennas are typically open loops.
Progress In Electromagnetics Research M, 2011
With the increases of the module integration density and complexity in electrical and power electronic systems, serious problems related to electromagnetic interference (EMI) and electromagnetic compatibility (EMC) can occur. For the safety, these disturbing effects must be considered during the electronic equipment design process. One of the concerns on EMC problems is induced by unintentional near-field (NF) radiations. The modeling and measurement of EM NF radiations is one of the bottlenecks which must be overcome by electronic engineers. To predict the unwanted different misbehaviors caused by the EM radiation, NF test benches for the reconstitution of scanning maps at some millimeters of electrical/electronic circuits under test were developed at the IRSEEM laboratory. Due to the difficulty of the design with commercial simulators, the prediction of EM NF emitted by active electronic systems which are usually based on the use of transistors necessitates more relevant and reliable analysis techniques. For this reason, the main focus of this article is on the experimental analysis of EM NF radiated by an MOSFET transistor with changing electrical parameters. Descriptions of the experimental test bench for the EM map scan of transistors radiation are provided. This experimental setup allows not only to detect the EM NF emission but also to analyze the influence of the excitation signal parameters ).
Unbalanced Currents in Integrated Circuits and Their Effect on TEM Cell Emissions
IEEE Transactions on Electromagnetic Compatibility, 2000
Transverse ElectroMagnetic (TEM) cell measurements are often used to evaluate the potential of ICs to cause radiated emissions in printed circuit boards. These measurements are a function of the unbalanced current on package power pins, for example, where more current enters one side of an IC than another, and the displacement current caused by capacitive coupling from the power grid mesh to the septum of the TEM cell. The relationship between unbalanced currents and TEM cell measurements is derived in this paper. A distributed model of the on-die power delivery network is developed to show that unbalanced currents may be caused by an asymmetric power pin arrangement, by an imbalance in package impedance, or by an imbalance in the impedance of the on-die power delivery network. To validate results, the magnitude and phase of high-frequency power-pin currents were measured on a test chip. Experiments showed that results could be used to guide modifications to the chip's connection to the printed circuit board power structure to minimize unbalanced currents and, thus, to minimize TEM cell measurements.
On the use of the source reconstruction method for estimating radiated EMI in electronic circuits
2010
Electromagnetic interference (EMI) regulations are a very important issue in the design of almost any electronic circuit. Over the years, "cut-and-try" procedures have been adopted by electronic designers to make circuits comply with these regulations, mainly due to the lack of reliable theoretical models of radiated noise and clear design rules. To gain new insight into this field, a novel approach is presented in this paper based on a well-known technique in the field of antenna design, i.e., the source reconstruction method (SRM). Its application allows a set of equivalent currents to be obtained that behave exactly like the circuit under consideration with regard to radiated noise. From these currents, magnetic and electric radiated fields can be obtained at any point in space, even at 3 or 10 m away from the circuit where the regulations must be met. Moreover, the equivalent currents accurately represent noise sources in the circuit, thus permitting the elements responsible for generating radiated noise to be located. The aforementioned method would enable designers to reduce the use of anechoic-chamber facilities when testing their designs, thereby leaving the chamber only for final certification purposes.