ABSTRACT
This chapter focuses on design and development of a conventional 5-bit switched-line phase shifter using metal-contact microelectromechanical systems (MEMS) switches utilizing a coplanar waveguide (CPW)-based transmission line. It demonstrates design, fabrication and characterization of the 5-bit CPW-based switched-line phase shifter. In a digital distributed MEMS transmission line (DMTL) phase shifter, typically about 8 RF MEMS switches are used to provide 90° phase shift and accordingly 16 RF MEMS switches periodically placed are needed for 180° phase shift. A digital DMTL phase shifter would therefore require a large number of switching elements and, accordingly, length of the phase shifter becomes large. There are a few aspects where more care can be taken to improve the reliability of the switched-line digital phase shifter. A stiffer beam can be used to overcome the variations in actuation voltage, but that inevitably leads to higher actuation voltage.
