Stochastic electromagnetic fields originating from processes in digital circuitry affect the operation of the circuit, increase the error rate in the transmission of digital signals, degrade the circuit's performance, yield malfunction of the system or even lead to a complete failure of the system's operation. Interference from stochastic fields are not only disruptive but are becoming more common due to the increasing complexity of modern electronics. Stochastic electromagnetic fields under common circumstances are due to a mixture of emissions from different sources, which makes a quantification of stochastic fields very challenging. Since digital signals are clocked, the ensemble averages of the electromagnetic field transients representing the digital signal exhibit a periodic time dependence with the period of the clock interval. The probabilistic model of the cyclostationary random process was composed by appropriate transformations of the initial discrete random process of the binary symbols. Exploiting the cyclostationary characteristics of stochastic fields greatly simplifies their analysis. The physical signal propagating along the transmission line is considered also a source of the radiating electromagnetic field which preserves the cyclostationary properties of the binary sequence. The stochastic process of the measured near-field emissions inherits probability characteristicsfrom the random process of the physical signal in the transmission line. This paper presents an approach for quantifying emissions and coupling of stochastic fields using their cyclostationary properties. For practical evaluation of cyclostationary characteristics the statistical cyclic averaging of the measured signals are used. The important feature of the statistical cyclic averaging procedure is its capability to distinguish cyclostationary signals from a mixture of stochastic processes such as stationary noise with deterministic signals and even from other cyclostationary signals with distinct cyclic frequencies. The measurement setup for observing electromagnetic emissions from printed circuit boards (PCBs) hosting digital electronic devices comprises an automated positioning system with a scanning near-field probe attached to the moving scanner head. This scanning near-field probe and a properly position fixed or also movable reference probe are connected to the inputs of a multi-channel digital oscilloscope for simultaneous and synchronous sampling and registering of the magnetic field components. The registered data from the oscilloscope was transferred to a data acquisition computer. After the postprocessing procedure, the spatial localization of distributed radiating sources on the surface of the PCB was performed in conjunction with determination of their average power characteristics and specified cyclic frequencies. The proposed cyclic averaging was applied to the spatial separation of radiating sources with different bit rates and for the quantitative characterization of crosstalk and coupling between transmission lines carrying the data sequencesand subsequent estimation of bit error rate (BER) caused by the crosstalk using their cyclostationary properties.

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Cyclostationary Characterization of Radiated Emissions in Digital Electronic Devices

This paper presents a detailed treatment of modeling of noisy electromagnetic field propagation as well as a formulation for its numerical implementation along with numerical and experimental examples. Modern electromagnetic interference measurement systems operate in time domain (TD) and exhibit gigahertz bandwidths together with short measurement times. Two-point near-field scanning with two field probes allows recording of near-field autocorrelation and cross correlation data as a basis for the TD simulation of noisy electromagnetic (EM) field propagation, also in complex environments. TD modeling yields results for the whole frequency band under consideration with a single computational run and is advantageous if results for a broad frequency range are of interest. We introduce a correlation dyadic-based approach for noisy EM field modeling using analytic TD Green’s functions. For experimental validation of the method, we have computed spatial cross correlations in the far field from experimental near-field scanning data of a digital circuit board under test. The propagated results are compared to cross correlations obtained from measurements performed directly in the far field.

Time-Domain Modeling of Noisy Electromagnetic Field Propagation

In this paper stochastic approach for Power Integrity, Signal Integrity, EMC and EMI analysis of moving objects is proposed. Circuit building blocks including mixers and distributed sensors for harmonic radars are presented. Dedicated wireless links for energy transfer, designed using Bond-Wire loops with scalable geometric profile and length, are experimentally characterized. Perspectives for multi-Physics Co-Design & Co-Analysis of moving probes for efficiently coupling signal information and material properties are drawn.

Stochastic approach for Power Integrity, Signal Integrity, EMC and EMI analysis of moving objects

In this paper, we present experimental characterization and analysis of radiated emissions from coupled UAV and smart RFIC Objects (smartphones) in presence of noisy interferers. Spectral and spatial Near-Field responses of radiated emissions from coupled Motor (UAV) and Circuit (smartphones) are extracted. Analysis of radiated emissions based on Energy density and Entropy considerations are proposed. Wavelet Multi-Resolution approach is introduced for the simultaneous Time-Frequency identification and localization of stochastic noisy sources.

Measurement and analysis of radiated emissions from coupled UAV and smart RFIC objects

Schottky barrier diodes (SBD) were integrated in a 0.25 /m SiGe BiCMOS technology. The SBDs were realized without additional process steps using the titanium silicide (TiSi) phase of the standard contact formation for the anode Schottky barrier. We observe a specific parameter degradation after reverse anode voltage operation. Different parameters as series resistance R s , forward and leakage currents (Ia, I r ) and design parameters like anode area, contact edge lengths and corners were evaluated in order to decrease this degradation. were extracted by s-parameter measurements and show an obvious decreased degradation. Finally maximum reverse operating voltages for a ten year life time and a maximum change of 10% for critical parameters were extrapolated for the worst operation conditions.

Reliability aspects of TiSi-Schottky barrier diodes in a SiGe BiCMOS technology

This paper presents the design and experimental characterization of High-Quality varactors and Schottky Diodes in SiGe:C Technology. A new layout topology for differential varactor is proposed to significantly improve its quality factor up to the Ka band. This new layout topology addresses the typical trade-off that designers often face between the quality factor and the tuning range. 2x improvement of the quality factor up to 30 GHz over conventional layout topology made of multi fingers is demonstrated. On the other side, special care has been taken to minimize parasitic capacitance between anodes to keep the tuning range stable. Measured VCO with this new type of varactor shows a reduction of 2 dB in the Phase Noise at 1 MHz from the carrier. Silicon-based Schottky Diodes arrays with Cut-Off frequencies in the THz domain are designed and fabricated. Concurrent optimization of Schottky Diode arrays geometry and electrical performances (Cutoff frequency, parasitic, Quality-factor, Sensitivity, Responsiveness, etc.) is carried out based on careful modeling and experimental characterizations. Analysis of the Schottky Diode arrays including sweep in DC-biasing conditions to control non-linearities is studied. Detection mechanisms related to the non-linear behavior are studied and figures of merit are introduced for their analysis.

High-Quality varactors and Schottky-Diodes in SiGe:C Technology for mm-Wave and THz applications

In this paper, modeling and experimental characterization of bond-wire arrays are proposed based on dedicated pilote carriers designed and fabricated for RF and microwave applications. Effects of the number of wire elements, connected in parallel to build bond-wire arrays, on the values of extracted broadband parasitics are investigated. Physical characterization of molding compound materials is proposed for their structural analysis and for broadband extraction of their dielctric properties (complex permittivity). Influence of molding compound properties on extracted parasitics of bond-wire arrays is highlighted.

Olivier Doussin

Papers

Stochastic approach for Power Integrity, Signal Integrity, EMC and EMI analysis of moving objects

High-Quality varactors and Schottky-Diodes in SiGe:C Technology for mm-Wave and THz applications

Modeling and characterization of bond-wire arrays for distributed Chip-Package-PCB Co-design