P. Kennis

Microwave performance prediction of a III–V semiconductor electrooptic waveguide modulator

The use of microwave modulations of optical waves allows one to obtain devices with very large bandwidths. Designers must solve two problems, one more specifically relevant to the optical field, the other in the microwave frequency range. The purpose of this paper is to focus the attention of optical device designers on microwave problems that occur when such modulators are made. To do so, we give some quantitative results relative to the microwave characteristics of such devices, when the hybrid nature of the microwave mode is taken into account.

Crosstalk Phenomenon in Coupled Microstrip Lines Laid on Semi-Conducting Substrates

Crosstalk phenomena and pulse propagation in coupled microstrip lines on insulating and semiconducting substrates are analysed. Propagation characteristics of these lines are obtained by Spectral Domain Analysis in order to avoid any error involved by the use of analytical model and T.E.M. approximation. Time domain results are calculated by a conventional fast Fourier transform. Effects of semiconducting layer, substrate thickness, lines spacing and length, loading impedances, on crosstalk and transfer are investigated.

Full Wave Analysis of Conductor and Substrate Losses in High Speed VLSI Interconnects

The determination of electrical properties of interconnects represents a critical design and analysis problem in the high-speed integrated very large-scale integration (VLSI) circuit in order to minimize signal distortion due to propagation delay and dispersion. In order to accomplish this, it is necessary to analyze and model the broad-band characteristics of submicrometer interconnects since the signals tend to exhibit both the short rising and falling times. Today, most extraction and delay analysis tools are limited to RC networks leaving an inherent unpredictability in the design process where inductive and substrate effects are suspected. However, the effect of a silicon substrate, which is negligible at low frequency, has a prevalent effect on the characteristics of lines during the operation of high-speed chips. One result of this study is to give a criteria that can be used to determine that a range exist for which inductance and substrate effects are not negligible, and which nets require a complete transmission line model.

Analysis of planar transmission lines and microshield lines with arbitrary metallization cross sections using finite elements methods

Propagation analysis is proposed to determine with much accuracy as possible, the dispersion characteristics for classical planar structures as well as for the new microstrip and coplanar membrane microshield lines both for microwave and millimeter wave ranges. These transmissions lines present an arbitrary cross section for the metallization of the strips and a finite value of the conductivity. We have developed two formulations of finite element methods in order to simulate such structures in the considered frequency range, showing the influence of lossy strips corner angles.<<ETX>>

Microwave characteristics of planar electrooptic modulator

An attempt is made to model traveling-wave optical modulators in the microwave frequency range by two methods: a desktop computer method based on the effective complex dielectric constant and a more rigorous method, i.e. the mode-matching technique. The aim is to quantify both bulk microwave and metallic losses and to determine the phase velocity in the microwave frequency range. This study takes into account the geometry of the cross section of the structure, the multilayered nature of the waveguide, and the hybrid nature of the mode. The two methods are compared for moderately lossy structures and shown to give quite similar results. However, when more realistic structures with highly doped multilayered substrates are considered, only the rigorous method can be used.<<ETX>>

Modeling of Passive Coplanar Elements for W-band ICS, Experimental Verification Up to 110 GHz and Parasitic Mode Coupling Study

The purpose of this work is to establish accurate broadband models of a complete CPW library of passive elements. These models are based on a distributed CPW line model, geometrical data and physical process parameters only and neither fitting parameter nor specific test structures are required. This whole CPW library can be directly introduced in any CAD packages. Comparison between measurement and models performed from 0.5 GHz to 110 GHz show the validity of the proposed approach. A multimode full-wave analysis has been used to verify the efficiency of air-bridges to suppress the slot-line mode.

Comparison Between a Full-Wave and a Quasi-Static Analysis for High-Frequency Interconnects Crossover in Multilayered Dielectric Media

Microstrip discontinuities such as open ends, gaps, steps, bends, T junctions and crossing, which are fundamental passive components in microwave ad millimeter-wave monolithic circuits, have been extensively analysed by several authors. For multilevel integrated circuits, what kind of new typical transitions occur? We find, naturally, via holes and crossover between conducting strips. To date little has been reported on the exact analysis of such complex structures. Our object is to study a strip crossover in a multilayered dielectric media. Although the full-wave analysis provides the highest degree of accuracy, it requires extensrve analytical and numerical calculations. In comparison, the quasi-static analysis are tradionally faster in term of CPU time and analytical process than full-wave techniques. The choice ofa faster numerical tool (a quasi-static model) needs to define the range of validity. This leads to develop a full-wave and a quasi-static analysis. That was done and we show for a typical structure the discrepancy versus frequency.

A modified matrix pencil moment method for multimode waveguide discontinuities analysis

This paper presents an original approach to analyze multimode waveguide discontinuities. The generalized scattering parameters are determined by a Matrix Pencil Moment Method (MPMM) associated with efficient numerically multimode matched loads placed at each physical port of the discontinuities. The analysis of both microstrip-coupled lines and coplanar lines asymmetric discontinuities is presented and successfully compared to experiments and available published results.

Scattering Parameters and Mode Conversion in Asymmetric CPW-Microstrip Overlap Transitions

In this communication, an asymmetric overlay transition between a microstrip and a CPW is studied. The mode conversion phenomenon is characterized by an efficient full-wave approach associated with the Matrix Pencil post-treatment.

An Extension of the NML simulation to the 3D Spectral Domain Analysis using Triangular Subdomain Functions

A clever way to simulate Numerical Matched Loads is presented and applied in the mathematical framework of the 3D Spectral Domain Analysis when triangular subdomain functions are used as both expansion and testing functions in the Moment Method.