A 50 MHz-30 GHz broadband co-planar waveguide SPDT PIN diode switch with 45-dB isolation

This paper reports on a GaAs PIN diode SPDT switch design which achieves 45 dB of isolation up to 30 GHz. The switch design uses 2-μm-thick i-region PIN's, a shunt-shunt-series switch topology in each arm, and a quasi-coplanar waveguide (CPW) design environment to achieve its superior isolation performance. By employing CPW ground isolation with a microstrip design, as much as 10-dB improvement in isolation performance was observed at the upper band frequencies. The switch achieves 1.02-dB insertion loss and >15-dB input and output return-loss across the band. In comparison to previously reported GaAs MMIC PIN diode switches at millimeter-wave frequencies, this design achieves state-of-the-art isolation performance.