Giorgi Muchaidze

Susceptibility Scanning as a Failure Analysis Tool for System-Level Electrostatic Discharge (ESD) Problems

Susceptibility scanning is an increasingly adopted method for root cause analysis of system-level immunity sensitivities. It allows localizing affected nets and integrated circuits (ICs). Further, it can be used to compare the immunity of functionally identical or similar ICs or circuit boards. This paper explains the methodology as applied to electrostatic discharge and provides examples of scan maps and signals probed during immunity scanning. Limitations of present immunity analysis methods are discussed.

A measurement technique for ESD current spreading on a PCB using near field scanning

Electrostatic discharge (ESD) can cause interference or damage in circuits in many ways e.g., by E- or H-field coupling or via conduction paths. Although we can roughly estimate the voltage and current at the injection point during an ESD event, the real offending parameter is mostly the ESD current spreading throughout the system. Those currents can be simulated if great simplifications of the system are accepted. However, even in moderately complex systems the ability to simulate is limited by lack of models and computational resources. Independent of the complexity, but obviously not free of its own limitations is a measurement technique that captures the current as a function of time and location through the system. This article describes the proof on concept of ESD such a measurement technique that allows reconstructing the spreading current as a movie from magnetic field measurements. It details the technique, question of probe selection and how to process the data to present the current spread as a movie.

Probe characterization and data process for current reconstruction by near field scanning method

previously a measurement technique for ESD current spreading on a PCB using near field scanning was developed in order to connect the local ESD sensitivity to system level ESD failures in time and spatial domain. The concept of such scanning methodology is proved and several scanning results were processed. However the validation, precision and weakness of such methodology need to be further investigated before the application of such scanning methodology on complex circuit or system. This article investigates the current reconstruction by near field scanning technique and methodology. It studies the probe factors including coupling frequency response characterization and deconvolution method, spatial resolution for scanning and orthogonal-scan data combine process.

Near field probe for detecting resonances in EMC application

Resonances degrade the products EMI or immunity performance at resonance frequencies. Near field scanning techniques, like EMI scanning or susceptibility scanning determine the local behaviour, but fail to connect the local behaviour to the system level behaviour. Resonating structures form part of the coupling paths, i.e., identifying them will aid in understanding system level behaviour of products. In this article, a near field probe (patent pending) is proposed to detecting the resonances frequencies, locations or resonating structures and their Q-factors. The probe is suitable for integration into an automatic scanning system for analysing resonances of PCBs, cables, structural elements etc. The mechanism of the probe has been verified with full wave tools (CST MWS and Ansoft HFSS). Two samples of application are presented.

A novel method for the analysis of ESD generators and coupling using frequency domain

A concept for analyzing ESD generators and coupling to EUTs in the frequency domain is presented. Its novelty lies in not only taking the current shaping, but also the radiation effects of structural elements and electrical components located within the ESD generator into account, without discharging the ESD generator. This is achieved by using the frequency domain and substituting the electrical breakdown within the ESD generator (contact mode) for one port of a network analyzer. The network analyzer excites all the pulse forming and the radiating elements of the ESD generator as they would be excited during a discharge. This offers the advantage of an increased dynamic range of frequency domain techniques without having to simplify the complex radiation properties of real ESD simulators. Keywords-Electrostatic Discharge; ESD, simulation, network analyzer

Developing a universal exchange format for near-field scan data

Near-field scan measurements and simulations generate a large amount of data. The format of the data is closely linked to the supplier of the acquisition or simulation software, rendering extremely difficult its exchange between suppliers, customers, EDA tool vendors, academics, etc. The paper describes how a universal exchange format for near-field scan data has been developed. The format caters for various coordinate systems and is suited to emission and immunity testing both in the frequency and time domains.

Effect of Inhomogeneous Medium on Fields Above GCPW PCB for Near-Field Scanning Probe Calibration Application

In this paper, a method is proposed to calibrate a probe by placing it into a known field and referencing its output voltage to the known field. A transmission line is a convenient structure for creating such a known field. This paper presents the effect of the inhomogeneous medium on the near-field generated over a grounded coplanar waveguide (GCPW) printed circuit board (PCB) and reports the field pattern over the GCPW. GCPW PCBs are used to determine the probe factor for near-field scanning applications. A near-field scan is performed to visualize the near-field sources over a device under test (DUT). The near-field is measured by using E- and H-field electromagnetic interference probes. The output of these probes is a voltage and using the probe factor, the field present over the DUT can be determined. To calculate the probe factor, the near-field strength needs to be known using the 3-D simulation. GCPW creates a quasi-TEM field. The effect of non-TEM modes is easily underestimated, such that non-TEM fields prevent the user from determining the unwanted field suppression of probes at higher frequencies.