MIC and MMIC packages capable of good performance at frequencies as high as 60 GHz need to have small volume, low weight, microstrip and/or coplanar waveguide (CPW) compatibility and exhibit negligible electrical interference with the rest of the circuit. In order to acquire some of these characteristics, special provisions need to be made during circuit layout and design, resulting in high-density packages. The designed circuits have a large number of interconnects which are printed on electrically small surface areas and communicate through the substrate in a direct through-via fashion or electromagnetically through appropriately etched apertures. In a circuit environment of this complexity, parasitic effects such as radiation and cross talk are intensified, thus, making the vertical interconnection problem very critical. In this paper, transitions using through-substrate vias are considered and analyzed both in the time and frequency domains using the Finite Difference Time Domain (FDTD) technique and the Finite Element Method (FEM), respectively. The merits of each method in conjunction with accuracy, computational efficiency and versatility are discussed and results are compared showing excellent agreement. Specifically, a microstrip short-circuit, a microstrip ground pad, a CPW-to-microstrip through-via transition and a channelized CPW-to-microstrip transition are analyzed and their electrical performance is studied. >

Characterization of high frequency interconnects using finite difference time domain and finite element methods

A system-level electromagnetic (EM) modeling tool combining a three-dimensional (3-D) full-wave finite-element EM-field analysis tool and a time-domain electric-circuit simulator is developed and applied to various geometries such as multilayer printed circuit boards (PCBs), signal lines embedded in a PCB or package, and split power-distribution network. Since the signal integrity is a primary concern of high-speed digital circuits, the noise distributions on various circuit planes are evaluated from the analysis. These noise distributions, often called voice maps, are utilized to identify the location of the major source of simultaneous switching noise (SSN). This information can eventually be adapted for optimum placement of decoupling capacitors to minimize the noise fluctuations on the various circuit planes on an entire PCB.

Application of system-level EM modeling to high-speed digital IC packages and PCBs

Two numerical techniques, the finite difference in time domain (FDTD) and the finite element method (FEM) in frequency domain, are employed to characterize microstrip hermetic transition geometries in an effort to investigate high-frequency effects. Measurements performed on these transitions compare favorably with theory. Two different types of transitions have been analyzed from 10 to 25 GHz and have been found to be limited in performance by higher return loss as frequency increases. It is shown that microstripthrough-CPW hermetic transitions in the shielded environment may suffer from parasitic waveguide modes which, however, can be eliminated with the use of vias at appropriate locations. The hermetic wall on top of the CPW section shows a relatively small (I 2 dB) effect on the original circuit performance. Similarly, the hermetic bead transition shows good performance at a lower frequency region while it degrades as frequency increases. This indicates the need for very careful characterization of transitions intended for use in microwave and millimeter-wave applications. 0 1996 John Wiley & Sons, Inc.

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Modeling of hermetic transitions for microwave packages

It has been shown that the finite difference time domain (FDTD) method is an accurate and flexible technique to simulate complex electromagnetic problems. A 3D-FDTD software package is introduced. It can be used to simulate electronic packaging problems from an electromagnetic field point of view. >

C. Wu

Papers

A new three dimensional finite difference time domain (3D-FDTD) simulator for modelling electronic interconnections and packaging