Saila Ponnapalli

A package analysis tool based on a method of moments surface formulation

A package analysis tool is described which is based on a method of moments analysis and surface formulation. The surface formulation replaces ideal conductors by electric currents on their surfaces; electric and magnetic currents are used for lossy conductors. These currents are then discretized using triangular linear current approximations, with the primary advantage of being able to represent arbitrary shapes. Frequency dependent inductance and resistance are computed using a novel approach. The capacitance is also computed using piecewise constant charge distributions on each triangle. The current and charge distributions are compatible, and therefore transmission line modelling can be done accurately. The algorithm enables use of the tool for both transmission line and discontinuity modelling, as well as inductance evaluation for analysis of simultaneous switching noise. The tool has a graphical pre- and post-processor, which allows analysis of highly irregular structures, as are found in most practical packaging configurations. In this paper, the algorithms for the tool are described. Comparisons are shown between results obtained using the approach of the paper and analytical and approximate calculations. Comparison is also shown with measured capacitance for irregular shapes. The analysis of simultaneous switching noise for a 304 lead, six layer single chip module is described. >

Methodology for evaluating practical EMI design guidelines using EM analysis programs

Most companies oflering products that mus t pass FCC or’ other regulatory agency specifications have compiled EMI design guidelines which are practiced b y their engineers. I n this paper, we take one such practical E M I design guideline and, through extensive use of a state-of-the-art electromagnetic analysis code, investigate its range of applicability, and show its lamitations. The emphasis is placed on the methodology, rather than the guideline itself, so that a framework is established under which other EMI design guidelines can be similarly “revisited”.

Frequency Domain Microwave Modeling Using Retarded Partial Element Equivalent Circuits

Full-wave electromagnetic modeling is used increasingly to model the properties of high speed interconnect or to predict electromagnetic interference. Retarded partial element equivalent circuit (rPEEC) models provide a way to simulate with full-wave accuracy in time and frequency domain without leaving the level of circuit simulation. This paper presents a new algorithm to simulate frequency domain rPEEC models efficiently.

Whip antenna design for portable rf systems

Whip type antennas are probably the most commonly used antennas in portable rf systems, such as cordless and cellular phones, rf enabled laptop computers, personal digital assistants (PDAs), and handheld computers. Whip antennas are almost always mounted on the chassis which contains the radio and other electronics. The chassis is usually a molded plastic which is coated with a conducting paint for EMI purposes. The chassis which appears as a lossy conductor to the antenna, has several effects -- detuning, altering the gain of the antenna, and shadowing its radiation pattern. Extensive modeling and measurements must be performed in order to fully characterize the affects of the chassis on the whip antenna, and to optimize antenna type, orientation and position. In many instances, modeling plays a more important role in prediction of the performance of whip antennas, since measurements become difficult due to the presence of common mode current on feed cables. In this paper models and measurements are used to discuss the optimum choice of whip antennas and the impact of the chassis on radiation characteristics. A modeling tool which has been previously described and has been successfully used to predict radiated field patterns is used for simulations, and measured and modeled results are shown.