Modeling and Optimization of Bond Wires as Transmission Lines and Integrated Antennas at RF/Microwave Frequencies

In this contribution, we present a systematic approach for optimizing the RF performance of bond wires. First of all, a comparative analysis between two of the most commonly used bond wire signal configurations, the two-conductor and coplanar configurations, is done. Our results reveal that although the partial self-inductance of the signal wires is the same in both configurations, the partial mutual inductance of the coplanar configuration is higher, resulting in a smaller loop inductance. Consequently, the return and insertion losses are smaller. By reducing the distance between the signal and return currents, we further reduced the loop inductance, and significantly optimized the coplanar configuration. For example, considering a 1 mm long bond wire with a diameter of 25 μm, we successfully kept the power lost through the coplanar configuration below 10% at 15 GHz, in comparison to the 70% power lost through the two-conductor configuration at the same frequency. However, more than 30% of the entire power is lost through the optimized coplanar configuration at 40 GHz. At such frequencies where bond wires are unsuitable to be used as transmission lines, we demonstrate that they are very efficient as antennas by designing a half-loop integrated bond wire antenna having a bandwidth of 3 GHz. For experimental verification, test samples were designed, fabricated and measured. An excellent correlation was obtained between simulation and measurement.