Low Loss RF MEMS Phase Shifters for Satellite Communication Systems

Abstract

RF MEMS represents an attractive enabling technology for future satellite communications systems. In particular, MEMS RF switch devices are characterized by low insertion loss, low power consumption, and minimal weight and volume, offering significant systemlevel benefits to space-based applications. The mechanical operation of the MEMS devices is expected to result in improved stability in radiation environments relative to semiconductor devices. A number of circuit applications of the MEMS technology have been explored, such as MEMS-based phase shifter circuits for electronically scanned antennas. These phase shifter concepts have been demonstrated and shown to provide unique capabilities with respect to loss, bandwidth, size and weight relative to competing technologies. A novel low-loss phase shifter, based on RF MEMS series switches and a single-pole four-throw (SP4T) switch design, is presented. The phase shifter is fabricated on a 200 μm-thick GaAs substrate, and occupies less than 12 mm 2 of space. The measured average insertion loss is ‐0.55 dB, with a reflection loss of less than ‐17 dB over the 8-12 GHz frequency range. The 2-bit phase shifter performs well up to 18 GHz with an average loss of only ‐0.85 dB and a near-perfect linear phase shift from DC-18 GHz. This is the lowest loss MMIC-type phase shifter to-date at 8-18 GHz.