Planar E-Band (71-76 GHz) Platforms for Integrating Millimeter Wave Photodiodes with WR-12 Waveguides

A planar 71-76 GHz integration platform is designed and fabricated for high-power radio-over-fiber (RoF) wireless photonic transmitters (PTs). The platform enables the integration of high-electron-mobility-transistor RF amplifiers and millimeter wave photodiodes (PDs), e.g., the waveguide triple transit region PD. An efficient electrical coupling between the PD chip and the rectangular waveguide (WR-12) output is attained through a low-loss grounded coplanar waveguide to a rectangular waveguide transition. The integration platform features a novel planar bias-tee design making use of a single quarter-wave coupled-lines (SCLs) section and slotted split-ring resonators (SRRs). The bias-tee network enables proper biasing for the PD chip and protects the hybrid integrated RF amplifier from being damaged by the DC bias voltage. The introduced design together with the WR-12 output enables the development of high-power (>17 dBm) PTs for mobile backhaul links and radar applications. Experimental characterization of the designed platform is introduced and compared to numerical results.