A High-Isolation and Highly Linear Super-Wideband SPDT Switch in InP DHBT Technology

This work presents an SPDT switch with more than 235 GHz bandwidth, fabricated using 800 nm InP DHBT technology. Three cascaded shunt stages were used to achieve high isolation and relatively large transistors within the 90–325 GHz operating range. The three stage design enhances the isolation and wideband property at the expense of slightly higher insertion loss. Within the full BW, an average isolation of >40 dB and an average insertion loss of 3–6 dB are achieved. Linearity measurements at 100 GHz yield a input referred PIN1dB of more than 16 dBm, which is close to the highest reported value for InP DHBT based SPDT switches at this frequency. To the authors’ best knowledge, this is the widest bandwidth of an SPDT switch achieved in any MMIC technology. This ultra-wideband switch with its high input referred PIN1dB opens up new possibilities for multi-band mm-wave and THz spectroscopy, ultra-wideband radar systems and multiband measurement instruments.