Guangyao Shen

Designing A 3D Printing Based Channel Emulator

This research explored the possibility of building channel emulators by utilizing fused deposition modeling (FDM) 3D printing technology, which provides a rapid and low cost method with high flexibility to produce parts with many shapes of interest. Algorithms are developed for obtaining the printing pattern and loss profile based on S parameters of a target channel to be emulated. Parts with different dielectric constants, and loss tangents can be printed using filament with high dielectric constant or conductive fillers. Those parts will be placed on a low loss transmission line. As a result, different channel emulators can be built with the advantage of avoiding complicated electronic components, and only being limited in the frequency range by the base trace and its connectors.

ESD Immunity Prediction of D Flip-Flop in the ISO 10605 Standard Using a Behavioral Modeling Methodology

As the ESD stress is becoming more and more important for integrated circuits (ICs), the ability to predict IC failures becomes critical. In this paper, an 18-MHz D flip-flop IC is characterized and its behavioral model is presented. The resulting IC model is validated in the setup according to the ISO 10605 standard. A complete model of the setup combining the IC behavioral model and the passive parts of the setup, including parallel and twisted pair harnesses, is built to estimate the failure prediction accuracy in a totally simulated environment. The results show that the model can predict the failure level with the error of less than 20% in parallel harness case and around 30% in the twisted pair case.

EMI control performance of the absorbing material for application on flexible cables

Common mode signals on flexible cables often cause unwanted EMI. Common mode currents can be controlled by applying electromagnetic absorbing materials to the flexible cables. This work presents a set of specially designed test apparatuses that allow the performance of absorbing materials to be estimated for three typical structures known to radiate: monopole antennas, loop antennas, and transmission lines. Two materials are compared for each of the apparatuses, and the resulting common mode and EMI metrics are presented. The amount and placement of absorbing material was optimized based on reduction of EMI and impact on signal integrity. The better-performing materials were further tested in the actual hardware (television), showing a lower reduction in EMI (of about 3 dB) compared to the test apparatuses. The possible reason for reduced performance is that the flexible cable may not be the only source of radiation in the more complex real system.

Designing a 3-D Printing-Based Channel Emulator With Printable Electromagnetic Materials

This paper explored the possibility of building channel emulators by utilizing fused deposition modeling (FDM) three-dimensional (3-D) printing technology. The FDM 3-D printing provides a rapid and economic method to produce parts with different shapes. An optimizing algorithm was developed for obtaining the printing pattern and loss profile. Parts with different dielectric constants and loss tangents can be printed. Those parts will be placed or directly printed on a low-loss transmission line to modify its transmission or reflection. As a result, different channel emulators can be built to emulate the S-parameter and eye diagrams of a target channel with the advantage of avoiding complicated electronic components and only being limited in the frequency range by the transmission line and attached connectors.

Terminal model application for characterizing conducted EMI in boost converter system

A terminal model is a common method to create equivalent models of boost converters in order to predict conducted emissions. In this paper, a characterization board was designed to measure the voltages across and currents flowing into the input side of a DC-DC boost converter automatically by changing the load conditions using the relays as switches. After the equivalent source was determined, the induced noise voltage at the test load was compared to that predicted by the model. The results indicate that the agreement with the direct measurement is quite good up to 100 MHz when the load is within the characterization range. The model is able to correctly predict the conducted emission of the converter in situations quite different from the characterization conditions, for example when an EMI filter is added.

Simple D flip-flop behavioral model of ESD immunity for use in the ISO 10605 standard

As the ESD stress is becoming more and more important for integrated circuits (ICs), the ability to predict IC failures becomes critical. In this paper, an 18 MHz D flip-flop IC is characterized and its behavioral model is presented. The resulting IC model is validated in the setup according to the ISO 10605 standard. A complete model of the setup combining the IC behavioral model and the passive parts of the setup is built to estimate the failure prediction accuracy in a totally simulated environment. The results show that the model can predict the triggering level with the error of less than 20%.

Radiated EMI Estimation From DC–DC Converters With Attached Cables Based on Terminal Equivalent Circuit Modeling

An equivalent two terminal model based on the Thevenin equivalents describes the common mode (CM) currents on the input and output side of two widely used types of dc-to-dc power converters—buck and boost. Thus, it describes a nonlinear circuit by a linear equivalent circuit. The maximized spectrum of the CM currents is extracted for converters with stochastic signals using a novel characterization procedure. The extracted Thevenin model is used in co-simulation combined with a full-wave electromagnetic solver to predict the radiated emissions from the system consisting of the shielded dc–dc converters with attached cables and a DC brushless motor as load. The results using the terminal model agree well with the measurements providing that the actual CM loads are within the range of CM loads used while obtaining the Thevenin equivalent circuit.

Source isolation measurements in a multi-source coupled system

An electronic system will commonly have multiple emission (or noise) sources, some of which are correlated while others are un-correlated. Measuring the contribution to a node voltage or branch current by an individual source with high accuracy in such a multi source inter-coupled system is a fundamental problem. The problem is further amplified when the signal processing following the measurements is highly sensitive to the error in the measured parameters. This article describes a filtering method which can isolate the measured parameter (voltage or current) of the contribution of other such sources while preserving the phase and magnitude associated with the source under consideration.

Design methodology for behavioral surface roughness model

The surface roughness of copper foils has a considerable impact on the signal integrity performance of transmission lines at high data rates and long propagation distances. Existing surface roughness models for low-loss transmission lines are inadequate for accurate characterization. A new behavioral model for analyzing the surface roughness effects has been developed. The model is applied in the design process by adding a dispersive term to the bulk dielectric to represent the loss due to the foil surface roughness. By adding a broadband dielectric model into the original transmission model, time- and frequency-domain performance improvements are achieved.

Simulation of ESD coupling into cables based on ISO 10605 standard using method of moments

ESD events can damage or upset electronic vehicle systems, so discharges to the electronic systems or to the attached cables need to be considered. Discharges to the cables or to coupling structures close to the cables were investigated and a Method of Moments (MoM)-based methodology for ESD simulation is proposed. The simulation results for test benches according to ISO standards were verified against measurements.