Analysis of Bond Wires and Proposal for Compensation Circuits in 73 GHz Applications

This work investigates the problems associated with bond wire interconnection in millimeter wave applications. The deteriorating effect of bond wire caused by the inductance and other parasitic parameters in the bond wire is analyzed against frequency. To improve the insertion loss and matching associated with bond wire, an impedance compensation circuit is designed at $73 \mathbf{G H z}$ consisting of a radial stub and microstrip line. Furthermore, simulations shows that the degradation in transmission loss performance and matching can be minimized by reducing the overall length of bond wire and increasing the diameter. The proposed solution is verified by the measurements of a 25 um diameter bond wire with and without compensation structure. The measured insertion loss is reduced to $\mathbf{- 3. 5} \mathrm{dB}$, compared to the -6dB insertion loss in bond wire interconnect without compensation. Moreover, the input and output return loss are better than $\mathbf{- 1 0} \mathbf{d B}$ at $\mathbf{7 3} \mathbf{~ G H z}$. Significant improvements in terms of transmission performance and impedance matching are observed, compared with an unmatched bond wire.