Christoph Keller

Fast Emission Measurement in Time Domain

According to the applicable standards, electromagnetic compatibility emission measurements are carried out in the frequency domain using a measuring receiver. In this paper, the theory, setup, and algorithms, as well as the practical aspects including the examples of a precompliance measuring system in the time domain, are presented. The advantage of this system is that the measurements can be carried out approximately 10-100 times faster with sufficient accuracy and signal-to-noise ratio in the detector modes peak, quasi-peak, and average.

Transfer Function Method for Predicting the Emissions in a CISPR-25 Test-Setup

The CISPR-25 standard is used in the automotive industry to characterize the electromagnetic radiation of electronic components. The setup is comprised of an electronic device, a cable harness, a metallic table, and an antenna. Dimensions stretch from a couple of meters for the setup to fractions of a millimeter for printed circuit board features. Numerical prediction of radiated emissions (RE) is of great usefulness for prediction of potential electromagnetic compatibility nonconformities in the early design process, but extremely difficult to be done for this setup as a whole. In this paper, we demonstrate how RE can efficiently be computed based on a setup as commonly used to model conducted emissions only, i.e., electric control unit and harness on infinite-ground plane. Applying Huygens principle and using it to generate a fixed transfer function between a particularly chosen Huygens surface and the antenna, we arrive at a novel computing scheme for RE. The scheme is applied for the antenna model and antenna factor-based calculations and demonstrates agreement with measurements within 5 dB range.

Advanced simulations of automotive EMC measurement setups using stochastic cable bundle models

This paper deals with modeling and simulation of cable bundles for automotive EMC tests. A new stochastic cable bundle model is presented. The parameters of the model are grouped into parameters for geometry, simulation, and disorder. Using a particularly developed cable bundle testbench, the model is validated against measurements and the parameter dependencies are investigated. The parameter study shows that the model is governed by one universal constant which describes the stochastics of the cable bundle and a characteristic density which is directly related to the cable bundle geometry. Finally, the model is used in an exemplary EMC setup whose device under test is a partially populated printed circuit board of an automotive electronic control unit. The simulation agrees very well with the according real life measurement setup.

Simulation of automotive EMC emission test procedures based on cable bundle measurements

Two time efficient simulation methods for the prediction of the conducted and radiated automotive EMC emission tests, respectively, are presented. To verify the correct prediction of the cable bundle model, a novel cable bundle test bench has been developed. It allows a fully automated network analysis with up to 32 ports. Several types of cable bundles are experimentally characterized under stochastic considerations. The system simulation for the conducted emission setup is partitioned into four parts connected on circuit level. The statistically analyzed voltage at the output of the line impedance stabilization network is in very good agreement to respective measurements. To simulate the radiated emission a novel method is presented, where the setup is partitioned by the use of Huygens principle. The simulated prediction of the antenna voltage is in good agreement with respective measurements. The presented approaches are very time efficient and therefore can be used effectively during product development.

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.

Understanding conducted emissions from an automotive inverter using a common-mode model

This contribution presents results from an investigation into conducted emissions of an automotive inverter in a component level EMC test setup with unshielded cables. The primary goal of the investigation is to develop a profound understanding of the shape of the disturbance voltages frequency spectrum at the line impedance stabilization network. Complying with that objective, common-mode currents are identified as the dominating noise currents, especially at the operating point of the inverter representing the worst case scenario regarding EMC performance. To support this conclusion, an AC simulation of a single-phase common-mode equivalent circuit of the system is presented. The resonances occurring in the noise spectrum and its overall shape are explained by the simulation within the frequency range of 100 kHz to 110 MHz. In addition, CY capacitors are used as common-mode filter elements. Based on the validated simulation model, the influence of the filter capacitors and their parasitic inductances are investigated.

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%.

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.