Compact, High-Isolation 110–140GHz SPST and SPDT Switches Using a 250nm InP HBT Process

A low insertion-loss (IL) and high isolation (ISO) single-pole single-throw (SPST) and single-pole double-throw (SPDT) is demonstrated in 250-nm Indium Phosphide (InP) heterojunction bipolar transistor (HBT). The switch employs a 90° hybrid coupler with independent reflective loads to break tradeoffs in IL and ISO ratio. Measurement results of the implemented SPST show IL of 0.77–2.7 dB and ISO of 22.5–40dB in 110–140 GHz. Measured results of the proposed SPDT show 1.42–3.8 dB IL and ISO of 33.8–53 dB in 110–132 GHz.