300 GHz Four Ways On-Chip Power Combiner Based on BCB Transmission Line

This work presents a broadband 300 GHz 4 ways on-chip power combiner based on
$\mathbf{10}\ \boldsymbol{\mu} \mathbf{m}-\mathbf{thick}$
. BCB transmission line. The BCB transmission line is heterogeneously integrated on existing
$\mathbf{50}\ \boldsymbol{\mu} \mathbf{m}-\mathbf{thick}$
InP HEMT process. This line has the merits of compact size, concise structure and high frequency pure mode transmission conditions, which is supposed to be proper for Terahertz Monolithic Integrated Circuits (TMICs) above 300 GHz. Based on the transmission line, a 300 GHz T-junction power combiner is designed and fabricated. The combiner chip size is only
$\mathbf{890}\times \mathbf{820}\ \boldsymbol{\mu} \mathbf{m}$
. On wafer measured results show that, the return loss is better than 10dB and the insertion loss is around 3.5dB across the 220-325GHz band. The good measurement results demonstrate the high frequency feasibility of this BCB transmission line.