A 15-to-45 GHz low-loss analog reflection-type MEMS phase shifter

A low-loss broadband reflection-type phase shifter (RTPS), showing constant phase shift from 15 to 45 GHz, was developed using MEMS technology. The analog phase shifter consists of two cascaded reflection-type phase shifters for 1:3 bandwidth. Air-gap overlay CPW couplers were employed for low-loss 3 dB coupling, and bridge-type MEMS variable capacitors were used for low-loss reflective terminations. The fabricated phase shifter shows the average insertion loss of 3.63 dB, and rms phase error of 3.7/spl deg/ from 15 to 45 GHz. Compared with the similar RTPS using GaAs PHEMT varactor diodes, much lower loss is observed together with improved bandwidth.