Chulsoon Hwang

• Missouri University of Science and Technology

In this article, a multi-physics modeling methodology is presented for predicting the acoustic noise induced by a multi-layer ceramic capacitor (MLCC) in mobile electronic devices. The modeling process involves using a prescribed methodology to extract the equivalent source at the resonance frequencies of a printed circuit board (PCB) and then deri...

Radio frequency (RF) desensitization is a common issue caused by high-speed components in modern electronic devices. Consequently, numerous studies have focused on characterizing and quantifying electromagnetic (EM) emission sources by using near field scanning to detect EM noise sources. However, before near field scanning, no predetermined thresh...

In this article, visualization of noise coupling paths is proposed and verified. The coupling coefficient ( CC ) is derived based on the Reciprocity theorem and time-average coupled power, which represents the contribution of each spatial point to the coupled power. The physical meaning of CC is demonstrated by relating the integrations of CC...

This article proposes a new physics-assisted genetic algorithm (PAGA) for decoupling capacitor (decap) optimization in power distribution networks (PDNs), which is a highly efficient approach to minimizing the number of decaps within an enormous search space. In the proposed PAGA method, the priority of the decap ports is first determined based on...

Multilayer ceramic capacitors (MLCCs) are commonly used on printed circuit board (PCB) power distribution networks (PDN) for decoupling purposes. However, an MLCC can act as a source to excite PCB vibrations due to noise ripples on the power rail. In this letter, four types of equivalent source configurations are studied and compared to represent t...

When a multilayer ceramic capacitor (MLCC) is soldered on a printed circuit board (PCB), the capacitor deformation generates a force on the PCB, which serves as a source to excite PCB vibration and generate unwanted acoustic noise. A MLCC can be used under any loading conditions as long as the power supply voltage remains below its rated voltage; t...

The power-aware input/output buffer information specification (IBIS) model does not correctly account for the delay change caused by supply voltage noise. This article presents a new modification algorithm that improves the accuracy of the IBIS model by including the power-supply-induced jitter (PSIJ) sensitivity effect; more specifically, the DC j...

This paper analyzes different methods for modeling a buck regulator among the variety of voltage regulator modules (VRMs) from the perspective of power integrity and assesses the accuracy of power supply induced jitter (PSIJ) predictions for each buck regulator model. To compare the buck regulator modeling approaches, methods for conventional passi...

Radio frequency desensitization issues comprise two components: noise radiation sources and the transfer function from noise sources to the victim antenna. For modern electronic products, noise sources are often located inside a compact metal enclosure, making it difficult to measure the transfer function using conventional methods. Moreover, openi...

In power distribution network (PDN) designs, a large number of decoupling capacitors (decaps) may be needed to satisfy target impedance limits. Many algorithms have been proposed and implemented for finding the optimal decap placement, including genetic algorithms (GA), and machine learning methods. In this work, an improved GA is proposed for find...

On-board electrical components can cause printed circuit board (PCB) vibration, thus generating audio noise if the electrical noise is in the audible frequency range. The electrical component-induced vibration can be equated to an external force applied to the PCB. This article presents a novel methodology to extract the equivalent force of electri...

Heatsinks may cause radiated emission and radio frequency interference problems when they are mounted on printed circuit boards. In this article, the radiation mechanism of heatsinks is systematically investigated using characteristic mode theory. The dipole moment is a commonly used equivalent source model for integrated circuits that drive radiat...

This article presents a new optimization method for complex power distribution networks (PDNs) with irregular shapes and multilayer structures using deep reinforcement learning (DRL), which has not been considered before. A fast boundary integration method is applied to compute the impedance matrix of a PDN structure. Subsequently, a new DRL algori...

Radio frequency interference can degrade the receiving sensitivity of antennas. The interference is usually caused by certain coupling structures, such as layouts without adequate grounding for the radio frequency signal return path. Those structures can be modeled as a set of equivalent dipole moments when they are electrically small. Herein, the...

Accurate evaluation and simulation of power noise is critical in the development of modern electronic devices. However, the widely used target impedance fails to predict the low-frequency noise generated in a device due to the existence of the dc–dc converter, whose output impedance can change under different loading conditions. A physical circuit...

In this article, a method for analyzing coupling mechanisms in radio frequency interference (RFI) problems is proposed. The partial element equivalent circuit (PEEC) method is first used to derive the retarded inductances and capacitances between different mesh cells. With the introduction of a novel partitioning algorithm, the capacitive coupling...

This article proposes a method to predict power supply induced jitter (PSIJ) at the inverter chain buffer output with the design parameters of power distribution network (PDN). The PDN is assumed to contain multiple decoupling capacitors with sufficiently different values for each branch. The relationship between PSIJ and PDN design parameters is d...

This article proposeda SPICE-compatible model to fast simulate the buzz noise problem in a camera device. Based on the reciprocity theorem, the proposed SPICE-compatible model consists of cascaded scattering (S) parameters extracted from the field coupling. It can provide an accurate estimation of the buzz noise transfer function (TF <sub xmlns:mml...

With the increasing switching frequencies and power densities in modern power converters, magnetic core losses are becoming more essential for efficiency and thermal optimization. Traditionally, the two-winding method suffers from sensitivity to phase error in practical measurements; this is mainly created by the unknown phase shift of a current-se...

Accurate core-loss characterization is essential to push the power density of power converters to their limits. However, existing core-loss measurement methods still have some limitations, such as a slow test speed and a complex probe calibration procedure. In particular, accurate phase-difference measurement is time-consuming because a fast Fourie...

This article presents an efficient methodology based on boundary integration to calculate the dc and ac impedance of power distribution networks (PDNs) for arbitrary-shape and multilayer printed circuit boards (PCBs). The proposed method adopts a boundary element method to extract inductances for the arbitrary parallel-plane shapes. Subsequently, t...

As more compact designs and more assembled function modules are utilized in modern electronic devices, radio-frequency interference (RFI) source reconstruction is becoming more challenging because different noise sources may contribute simultaneously. This article presents a novel methodology to reconstruct multiple random noise sources on a real-w...

Modeling and simulating a power distribution network (PDN) for printed circuit boards with irregular board shapes and multi‐layer stackup is computationally inefficient using full‐wave simulations. This paper presents a new concept of using deep learning for PDN impedance prediction. A boundary element method (BEM) is applied to efficiently calcula...

In memory devices, such as solid-state drive, multitopology is used for interfaces where multiple memory packages are connected to a controller using a branched transmission line. Impedance mismatching caused by the branches and unwanted reflection from deactivated packages inevitably degrades signal quality, limiting the data rate of the interface...

This article proposes a jitter-aware decoupling capacitors placement optimization method that uses the genetic algorithm (GA). A novel method for defining the optimization target function in regard to power delivery network (PDN) and power source-induced jitter (PSIJ) optimization based on the GA-based tool is proposed. The proposed method can prov...

Modeling and simulating a power distribution network (PDN) for printed circuit boards (PCBs) with irregular board shapes and multi-layer stackup is computationally inefficient using full-wave simulations. This paper presents a new concept of using deep learning for PDN impedance prediction. A boundary element method (BEM) is applied to efficiently...

In this work, a generalized power supply induced jitter (PSIJ) model is proposed. The PSIJ sensitivity is obtained based on the evaluation of driver power supply rejection ratio (PSRR) response. The voltage ripple at the driver output is transformed into driver output jitter with the slope of the switching edge. The time-averaged effect of power no...

This article demonstrates an inaudible attack on smart speakers using electromagnetic interference (EMI). The EMI induces voltages on the order of a few millivolts on conductors, which are then converted into baseband signals by exploiting the inherent nonlinearity of microphones. The EMI signal is specially preprocessed to minimize the useless har...

Presents corrections to the above named paper.

Presents corrections to the above named paper.

The conventional definition of shielding effectiveness (SE) is well suited for calculations of far-field electromagnetic shielding. However, in the near field, SE calculations are not as straightforward. In radio-frequency interference (RFI) problems, the majority of field coupling occurs in the near field. Thus, a well-defined method for calculati...

In this article, multilayer ceramic capacitors (MLCCs) induced acoustic noise is studied through simulation investigation of the vibration behavior of the printed circuit board (PCB). The board vibration theory is briefly summarized to understand the key parameters influencing intrinsic board vibration properties. The identified key parameters are...

Source reconstruction using equivalent dipole moments to replace the original noise source is widely used in radio frequency interference. The conventional reconstruction methods only work well in the cases of free space or with a large ground plane. In this article a new method is proposed for source reconstruction over an arbitrarily shaped groun...

In this article, an improved target impedance concept directly correlating circuit output jitter with power distribution network (PDN) R - L - C parameters is proposed. A systematic procedure to develop the target impedance curves is formulated and developed for common CMOS buffer circuits. The relationship between output jitter and PDN R-L-C...

This article proposes a novel radio frequency interference (RFI) mitigation method and applies it to a real consumer electronic device. Through near-field scanning, an equivalent dipole moment of the noise source containing the CPU and DDR memory chip is reconstructed. The near-field components of the victim Wi-Fi antenna are measured to obtain the...

In this article, acoustic noise of printed circuit board (PCB) introduced by multilayer ceramic capacitors (MLCCs) on power distribution network (PDN) is studied. The correlation of PDN power rail noise, MLCCs and PCB dynamic characteristics, and PCB acoustic noise is demonstrated on a real mobile product through electrical, vibrational, and acoust...

A new method to visualize the coupling path is proposed to help solve electromagnetic compatibility problems. By using the reciprocity theorem and the concept of reaction, the coupling density coefficient (CC) is defined. Integration of the CC on closed surfaces equals the coupled power at the receiver. By plotting the CC on a set of surfaces from...

The mechanism of a universal serial bus 3.0 connector caused radio frequency interference (RFI) to a nearby antenna is studied. The connector radiation is modeled by an equivalent stripline-fed slot antenna, based on the analysis of the common mode current path on the connector structure. With the proposed connector model, the original connector ra...

Display modules have become inextricable components in recent mobile platforms; however, displays also represent the most common noise sources contributing to radio-frequency interference (RFI) issues. This paper considers RFI issues caused by power management integrated circuits (PMIC) that support display modules in practical mobile devices. The...

A transfer function based calculation method is proposed to estimate radio frequency interference (RFI) problems. The closed-form equations are analytically derived from Maxwell's equations and the reciprocity theorem. The derived equations can clearly decompose the RFI problem into two parts: the noise source and the coupling transfer function to...

In mobile platforms, RF interference issues caused by the switched-mode power supply (SMPS) ringing noise often arise in the on-the-go mode and the charging mode of the interface power management integrated circuits. In this paper, we introduce the modeling method for the SMPS ringing noise in the conventional two-level dc-dc converters and then, b...

In a near-field scanning system, each element of the measurement chain contributes to the thermal noise power density: probe, cables, amplifiers, and the measuring instrument. The signal-to-noise ratio (SNR) is strongly affected by the source output impedance, source temperature, the lossy transmission lines between probe and amplifiers, amplifier...