Phase Shifter Design Based on Fast RF MEMS Switched Capacitors

This paper presents the design and fabrication of fast DMTL RF MEMS phase shifters. Distributed MEMS Transmission Lines are being used with miniature RF MEMS switched capacitors (40 times 40 mum²), actuating at 25 V with a switching time around 1 mus. Both 90 and 180 degree phase shifters presented here operate at 20 GHz, are respectively less than 4.5 mm and 8.5 mm long. They are designed with 6 and 12 unit cells to achieve the desired phase shift. Measured return loss is respectively better than -13 dB and -11 dB for the 90 and the 180 degree phase shifters, and insertion loss is respectively less than 0.8 dB and 1.8 dB at 20 GHz.