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 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 100MHz 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.