PROJECT DESCRIPTION, MOTIVATION, & RELATED WORK
Emerging millimeter-wave (MMW) systems continue to require more compact, low-cost, interconnect and packaging solutions, for high data rates (>1 Gbps) wireless communications and automotive radar applications. Because mechanical tolerances, grounding techniques, and interconnect lengths play a crucial role in the high frequency device performance, packaging costs account for a larger portion of the total manufacturing cost at MMW frequencies. Although IC technologies for MMW systems are experiencing a cost reduction as improvements are made, progress in the high frequency packaging has been somewhat slower. This has lead to unexpected results in fabricated MMW systems, caused by interconnects exhibiting undesirable high-frequency behavior such as cross talk, radiation, and EMC related problems. In the end, a great deal of time and money has been spent in back-peddling and fixing the designs to account for the high-frequency packaging effects. Therefore, simulation models that accurately depict high-frequency behavior of MMW interconnects are greatly desired because they ensure high first-time design successes.

The overall objective of this project is to create high-frequency models for Motorola that provide accurate results at frequencies as high as 65 GHz. This will lead to the development of low-cost IC-to-package-to-motherboard interconnect strategies for MMW applications. In so doing, material and mechanical issues have to be taken into account, as well as the interactions between the IC, package, and motherboard designs. One very cost-effective strategy would be to develop accurate high-frequency interconnect models for bond wires, ribbon bonds, microstrips, waveguides, etc. that could be integrated into Agilent’s Advanced Design System (ADS) simulation software. Then the interaction between the IC, package, and motherboard designs could be properly characterized and analyzed before fabrication, resulting in time and cost savings.

Fig. 1. Comparison of simulated and measured S-parameter data for a bond wire. The measured data is courtesy of Motorola. These results represent two bond wires in parallel, each having a length of 60 mil and a diameter of 1 mil.

Fig. 3. Comparison of simulated S-parameter data between an HFSS 3-D bond-wire model and an equivalent ADS transmission-line bond-wire model (shown in Fig. 7). These results are for a 100-mil long bond wire.