Analytical modelling of microstrip-like interconnections in presence of ground plane aperture

High-speed multichip module interconnects are characterised by planar transmission lines. An interconnect line with ground plane aperture is essentially a microstrip line with partially removed ground plane below the line. The authors report the closed-form analytical expressions for line capacitance and characteristic impedance of microstrip interconnect line with a ground plane aperture. The expressions have been obtained using variational analysis combined with transverse transmission line technique. The closed-form expressions are general and are obtained for a range of structure parameters and the dielectric constants. Results are compared with finite-difference time-domain simulations and measurements performed on a vector network analyser. The proposed study can find applications in the design of high-speed interconnects for printed circuit boards, radio frequency (RF) and multichip module applications. These are particularly useful where high impedance lines are required.