Ultrawide Bandwidth Chip-to-Chip Interconnects for III-V MMICs

Ultrawide bandwidth coplanar waveguide interconnects between GaAs chips based on a novel fabrication process are demonstrated. Fabricated structures on 100 μm thick GaAs chips exhibited chip-to-chip insertion losses below 1 dB up to 110 GHz, and below 2.2 dB up to 220 GHz from on-wafer S-parameter measurements. A return loss larger than 10 dB from 100 MHz to 220 GHz was measured. The measured responses are consistent with numerical simulations, including the effects of excess solder at the chip-to-chip interface. Numerical simulations indicate that further improvements in performance, with insertion losses as low as 1.1 dB at 220 GHz, should be possible by minimizing the excess solder.