Phase shifters are high value components within phased array antenna architectures. Phased array antennas have many advantages over traditional antenna concepts, including fast, reliable electronic beam steering, a compact volume profile, and graceful degradation with device failures. To date, however, traditional phased array antennas have been constructed with expensive active electronics behind every radiating element severely limiting the degree to which this type of antenna architecture has been deployed in communication systems.
One option for communications antennas is to utilize “passive” array approaches where each radiator is driven by an ultra-low loss phase shifter, and where multiple radiator/phase shifters are fed by a single electronics module. A block diagram for this antenna architecture is shown in the figure below. This option is very cost effective as it amortizes the expensive electronics (the module) over 4, 8, or 16 radiators. However, in this architecture, phase shifter losses must be considerably lower than are realized with conventional microwave electronics technology. Typical pin-diode or GaAs FET based 4-bit phase shifters typically have 4-5 dB of loss at X-band while at Ka-band they have 8-10 dB.
Block diagram of a low-cost, passive, electronically scanned antenna
The primary technology for realizing the required low loss phase shifters is micromachined RF MEMS switches. MEMtronics is developing phase shifters based on their own proprietary low-loss capacitive MEMS switches to enable passive high performance phased array antennas from X-band through Ka-band and beyond. The most important features of these phase shifters are their very low insertion loss, negligible power consumption (10s of nanojoules per switch cycle), and high linearity (third order intercept points exceeding +66 dBm). The insertion performance obtainable with these components far exceeds that obtainable with phase shifters utilizing pin diode or GaAs FET switch technology. Shown in the figure below is a prototype fully packaged 4-bit Ka-band phase shifter created with RF MEMS switching technology. The chip size is 1.7mm x 5.4mm.
Fully packaged prototype 4-bit MEMS Ka-band phase shifter
The flexibility of MEMtronics’ MEMS processes make their switches excellent candidates for co-integration with other electronics technologies – control CMOS, GaAs electronics, etc. to meet specific customer requirements.
If you have microwave or millimeter-wave applications similar to these, please feel free to contact a MEMtronics representative. We are always interested in talking with potential customers and collaborators on how MEMtronics’ phase shifter technology may benefit their application.