A 50-MHZ 30-GHZ BROAD-BAND COPLANAR WAVE-GUIDE SPDT PIN DIODE SWITCH WITH 45-DB ISOLATION

This paper reports on a GaAs PIN diode SPDT switch design which achiev es 45 dB of isolation up to 30 GHz. The switch design uses 2-mu m-thic k i-region PM's, a shunt-shunt-series switch topology in each arm, and a quasi-coplanar waveguide (CPW) design environment to achieve its su perior isolation performance. By employing CPW ground isolation with a microstrip design, as much as 10-dB improvement in isolation performa nce was observed at the upper band frequencies. The switch achieves 1. 02-dB insertion loss and >15-dB input and output return-loss across th e band. In comparison to previously reported GaAs MMIC PIN diode switc hes at millimeter-wave frequencies, this design achieves state-of-the- art isolation performance.