Compact mm-wave power combiners in 65nm CMOS-SOI

Compact, slow-wave coplanar waveguide (S-CPW) power combiners are characterized in the 60GHz band. A floating electric shield promotes slow-wave propagation, while implementation in 65nm CMOS-SOI technology allows utilization of the entire interconnect metal stack to lower losses. Measured slowing factors as high as 11 lead to a reduction in size by a factor up to 4.4 for a 60GHz combiner. Measured attenuation and insertion loss of the S-CPW combiners are <;0.3dB per λ/4 and <;0.6dB/150μm length at 60GHz, respectively, with quality factors ranging from 25 to 45. The effects of ground-signal gap and shield density on characteristic impedance, attenuation, Q-factor and effective permittivity are described.