E. Paleczny

Theoretical limits for signal reflections due to inductance for on-chip interconnections

Transmission line properties of on-chip wiring need to be taken into account due to the great lengths and fast rise times encountered. As the line lengths and circuit speeds increase, the wavelength decreases, and the distributed n-section RC representation will be no longer adequate to analyse signal integrity. With these trends it is becoming more important to include inductance when modeling on-chip interconnect. The electrical phenomena that have to be investigated are governed by the electromagnetic theory. We present first in this paper an efficient and accurate modeling and simulation technique of frequency-dependent transmission lines to determine interconnection characteristics. The electromagnetic approach is then used to determine the limits where effects such as signal reflections can be predicted. The theoretical limits calculated are then illustrated.

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>>

Impact of inductance on timing characteristics of VLSI interconnects

As the result of the scaling down of technology and increased chip sizes, the cross-sectional area of wires has been reduced. With these trends, it is becoming crucial to be able to determine which nets within a high speed VLSI circuit exhibit prominent inductive effects. The object of this paper is to answer a question frequently put to designers: is inductance necessary to model interconnections or can a simple RC model be sufficient? By comparing the simulation results obtained from electrical simulations to an electromagnetic approach we can verify if the RC distributed model is always sufficient to characterize the propagation delay and the degradation due to the interconnect lines in submicronic circuit. Limits between RC and RLC models are determined.

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.

Full Wave Analysis and Electrical Modeling of Eight Copper Interconnects Placed in a Giga-Scale Integrated Environment for Signal Integrity Evaluation

Signal integrity analysis on eight unintentionally coupled copper interconnects is derived from an equivalent distributed electrical multi-conductor cell. Compatible with SPICE environment, this elementary cell is calculated with a full wave analysis such as tangential vector finite element method and the transmission line theory. After R, L, C, G and mutual extraction, two types of excitation are implemented based on one aggressor and seven victims and vice versa in order to weigh the influence of parasitic mutual via crosstalk evaluation

On the analysis of four symmetrical interconnects for signal integrity evaluation

The purpose of this paper is to explain the way used to determine the electrical frequency dependant equivalent circuit of four coupled interconnects located on the same level. This is done with a full wave finite element method in one way, and the analysis of four symmetrical lines with the telegrapher transmission line equation and coupled mode theory in another way. Once the equivalent R/sub i/, L/sub i/, G/sub i/, Q/sub i/, Z/sub ij/,Y/sub ij/ circuit is determined for SPICE model, signal integrity is analyzed when the victim line is, for example, separated from the aggressive one by two and three interconnects.

Electrical performance of single and coupled Cu interconnects for the 70 nm technology

This paper deals with propagation delay, rise time and crosstalk for Cu wire of 100 nm width and 2.2 to 1.7 aspect ratio AR ( AR /spl sime/ h/w) in single and coupled configuration. Electrical and electromagnetical characteristics are predicted, with a full wave analysis, for various wire resistivity and low k dielectric material when a clock pulse of 143 ps period (7 GHz) propagate. Critical value of 300 /spl mu/m is calculated for wire length when propagation delay equals MOSFET switching delay. Such critical values also induced more than 20% crosstalk in two coupled lines with 100 nm spacing and low k=2.0.

Full Wave Analysis of Superconducting Microstrip for MMIC Applications

We take into account the influence of the superconducting nature of the strip in order to study the behaviour of the superconducting microstrip line by means of two numerical methods. The first one is the Spectral Domain Approach modified by the surface impedance concept and the second one is the modified mode matching technique. This last one allows to simulate more accurately the presence of the superconducting strip without using surface impedance approximation.