Millimeter-Wave Dielectric Slab-Based Chip-to-Chip Interconnect Network Allowing for Relaxed Assembly Tolerances

Abstract

An on-chip, low-loss, and wideband transition to dielectric slab waveguide is proposed in this article, for millimeter-wave interchip communication network applications. The transition design features a three-terminal circuit with one on-chip planar microstrip line and two off-chip dielectric slab-waveguide ports. It presents an add-drop attribute, which can be employed to realize the traditional bus and backbone network topologies. Prototypes presented operate on a thin-film layer imitating the back-end-of-line layers of a chip. Measurements are performed for an end-to-end connection and a hexagonal ring interconnect network at 170 and 100 GHz, respectively. In addition, the proposed transition is shown to enable an equal signal power distribution scheme in a linear array of receivers. To provide much needed relaxation against mechanical tolerances and thermal expansion effects in multiport circuits based on the ceramic dielectric waveguide, a novel low-loss and mechanically flexible connection between two dielectric slab waveguides is presented. The design of this connection, operating from 80 to 100 GHz, is verified by measurements. Technical merits, packaging attributes, and limitations of the proposed single hierarchy interchip interconnect network are discussed.