D. Morlion

Modeling differential via holes

In this paper, we present a method to characterize differential via holes in printed circuit boards in a both fast and accurate way. The via hole is modeled as a cascade of capacitances and inductances. We use FASTCAP to compute the values of the capacitances, and a closed form formula to obtain the inductance values. The numerical predictions are compared with experimental data.

Modelling complex via hole structures

Derives a physics-based circuit model for complex via hole structures in printed circuit boards. The via hole is modeled as a cascade of capacitance and inductance matrices. Capacitance values are computed using a three-dimensional electrostatic solver and inductance values are computed from a two-dimensional quasi-TEM solver. This model is valid at frequencies up to a few gigahertz for typical via hole geometries, where the return current follows a well defined path.

Modelling differential via holes

With the ever-increasing frequencies of printed circuit board (PCB) interconnections, the role played by via holes is no longer negligible. Thoughtless design of via holes on a board may seriously degrade signal integrity due to reflections, ground bounce, etc. However, the characterisation of via holes has not drawn much attention until now. This paper presents a method for the characterisation of differential via holes as a cascade of capacitances and inductances. Capacitances are computed using FASTCAP and inductances using simple analytical models.

Transfer impedance measurements on the shielding of a multi-pins board-to-board connector

A new triaxial test fixture has been developed for measuring the transfer impedance of the shield of a board-to-board or backplane connector. A lot of attention has been paid to the design of the outer and inner line of the test cell. As a reference, first transfer impedance measurements were done on a commonly used coaxial cable where a good agreement with literature results was found. Various configurations of the connector shield were further measured and compared, showing a large influence of the omission of side and bottom parts of the connector shields.<<ETX>>

Accurate characterization of a high-speed and high-density multichip module connector

As a consequence, these interconnections should be considered as real circuit components, of which the high-frequency behaviour (including for example the frequency limit) has to be known. Electromagnetic modelling is usually not feasible since the structures under test often have a complex three-dimensional shape. Therefore, accurate high-frequency measurements are required. Based on these measurements, a high-frequency model, such as a Spice-model, which is indispensable for the system dcsign. can be derived for the package or the interconnection under test.

A procedure for accurate high-frequency characterisation of multi-pins backplane connectors

In this paper we present a procedure for the measurement of the high-frequency characteristics such as reflection, transmission and crosstalk of packages. Although the approach is valid for general packages, we apply it here to the specific case of multi-pins backplane connectors. The high accuracy of this procedure is needed to characterise the connectors over a wide bandwidth or a large range of rise times. Based on the measurements, equivalent models are derived that can be used in circuit design.