A novel equivalent circuit for on chip transmission lines modeling

Microstrip transmission line (MS), coplanar waveguide transmission line (CPW), grounded coplanar waveguide transmission line (GCPW), slow-wave transmission line with slotted grounded shields (GSCPW), slow-wave transmission line with slotted floating shields (FSCPW) are widely used in the silicon technology. Because the quasi-TEM assumption is still valid in these structures, an equivalent circuit is proposed to model all these structures. In this work, we notice that for some types of transmission lines, say GCPW and GSCPW, the per unit length capacitance increases with frequency. An LC series subcircuit is proposed to model this phenomenon. For CPW, GCPW, GSCPW and FSCPW, the model has very good accuracy and fits the measurement results very well up to the highest measurement frequency (40GHz). For MS, the results from the 3D EM simulation software are adopted and the model shows a great agreement with the simulation results up to the highest simulation frequency (100GHz).