Coplanar waveguide to slotline transitions

The uniplanar configuration has having a growing popularity in the area of microwave integrated circuits. Fundamentals uniplanar configurations are the coplanar waveguide (CPW) and the slotline(SL). Well known advantages with respect to the microstrip line configuration are: easy shunt and series mounting, elimination of via holes, reduced radiation loss (for CPW), use of thicker substrates overcompensate the necessity for air bridges to suppress the spurious slotline mode in the CPW. The lack of accurate design tools however has prevented an extensive application of uniplanar technology, of which the transition between CPW and SL is a key element. The FDTD method has been employed to analyze several types of CPW-SL transitions including the effects of the coaxial connectors, air bridges, shielding effects as well as interactions between discontinuities. Theoretical simulations show excellent agreement with experimental data appeared in the literature.

Hybrid integrated circuit bonding:

The bonding wire interconnection is a key element for the fabrication of hybrid integrated circuits. It is employed to connect solid state devices to passive circuit elements as well as multichip modules. In spite of its small physical length, when millimeter-wave operations are required, the discontinuity introduced by the bonding wire can significantly affect the performance of the whole circuit. At the University of Perugia, the bonding wire interconnection has been studied from the point of view of its modeling and electrical characterization. In particular, two electrical models of the bonding wire have been developed. First, the Finite Difference Time Domain (FDTD) method has been adopted to rigorously analyze several bonding wire configurations (including multi-chip, single- and double-wire structures) and to produce reference results. Then, a quasi-static model of the bonding wire has been derived. This model is based on the representation of the structure with four uniform transmission line sections. Such an approach is suitable for commercial microwave CAD tools since the model parameters can be evaluated analytically from the dimensions of the structure.