A Compensated Finite-Ground Elevated Coplanar Waveguide Interconnect Strategy for InP Based Integrated Circuits Above 100 GHz

In this paper, a low-loss interconnect strategy for InP integrated circuits operating above 100 GHz is proposed. The interconnect strategy is based upon finite-ground elevated coplanar waveguide (FG-ECPW) structures and requires no through-substrate vias (TSVs) or backside processing. To minimize the reflection losses at the FG-ECPW discontinuities, the ground bridge parasitics are compensated leading to a seamless transmission characteristic through FG-ECPW structures such as Tee-junctions, bends and crosses. The compensated FG-ECPW interconnects have been implemented in a high-speed, mixed-signal InP DHBT technology from III-V Lab. A compensated FG-ECPW meandered line with an accumulated length of 1.65 mm shows a resonance free, single-mode transmission characteristic with an average insertion loss of 2.4 dB in the full D-band from 110-170 GHz. The measured improvement in insertion loss is 3.7 dB at 170 GHz over a similar noncompensated FG-ECPW meandered line.