The design, fabrication, and experimental characteristics of InGaAs PIN diodes are presented for InP-based W-band monolithic integrated switches. The diodes with 10μm-diameter were used and showed a breakdown voltage of 17 V, a turn-on voltage of 0.36 V, and a switching cutoff frequency of 6.3 THz. The monolithic integrated switches employed microstrip transmission lines and backside via holes for low-inductance signal grounding. A radial stub-based design was used for on-chip biasing, and the high-frequency characteristics of the switches were verified by on-wafer W-band testing. The SPST PIN monolithic switch demonstrated 25 dB isolation, 1.3 dB insertion loss, and 0.8 dB reflection loss at 83 GHz.
