A high frequency model based on the physical structure of the ceramic multilayer capacitor

Abstract

Abstract-In this paper modelling of the high frequency behavior of ceramic multilayer capacitors based on device physics is presented. An accurate predictive model incorporating physical dimensions, material constants and aspects of the CMC application environment is presented. This model is suitable for use in the design and development of improved high frequency CMC structures. I. INTRODUCTIONThe physical modelling described in the following is primarily intended for the designer of high frequency ceramic multilayer caManuscript received September 27, 1991; revised March IO, 1992. The authors are with the Delft University of Technology, Department of Electrical Engineering, Laboratory for Telecommunication and Remote Sensing Technology, P.O. Box 5031, 2600 GA Delft, The Netherlands.IEEE Log Number 9200934. pacitors (CMC's). Secondarily, users of CMC's can gain insight into the optimal placement of CMC's in their application environment. T H E MODELIn 1991 Pema proposed a simple resonant folded transmission line model for a CMC mounted in series in a transmission line [ I ] . In 1987 Ingalls and Kent reexamined Pema's folded line model [ 2 ] . They tried to give the model a more rigorous basis and measured devices using the latest VNA's. This study has resulted in a more fundamental predictive model which has subsequently been proven in practice.The structure under study is that of the intrinsic CMC mounted in an application environment as given in Fig. 1. It is clear from the figure that the capacitor conceptually consists of the following three regions:The terminations:The interconnects:The capacitive part: connection of the electrodes and the metallization. interface between the terminations and the central capacitive region. this is the actual capacitor consisting of a rectangular block of ceramic dielectric in which a number of interleaved preciousmetal electrodes have been chosen to yield high capacitance per unit volume.Transformation to an equivalent circuit model may be made by treating the electrodes and the terminations as multiconductor sections. This requires the accurate calculation of the multiconductor parameters. The device simulator PISCES has been used to carry out these computations [3]. In our case its use is limited to the calculation of the capacitance per unit length between the conductors. These conductors are entered into the program as cross-sections separated by ideal insulating materials whose dielectric constants correspond to those of the CMC under consideration. Solutions are found in a two dimensional plane which somewhat restricts the validity of the model for complicated structures at higher frequencies (i.e. a 100 pF capacitor with 6 plates is accurately modelled up to I O GHz, a similar 330 pF capacitor model is accurate up to about 9 GHz). This restriction lies in the fact that there are a small number of three dimensional discontinuity regions which can not be accurately calculated in this way. Keeping these restrictions in mind, we can transform the physical structure int...

A study of the high frequency performance of thin film capacitors for electronic packaging

“…Computer simulation is a very useful aid in forecasting and envisioning the performance of capacitors. Some ceramic capacitors and thin film capacitors have been studied using different modeling and simulation methods [10]- [14]. Our goal was to study the high frequency performance of thin film capacitors using the finite element method.…”