Millimeter-wave microelectromechanical (MEMS) switches for automotive surround sensing systems

RF MEMS for automotive radar sensors

“…Radio-frequency (RF) MEMS switches and tunable capacitors are the principal components of most RF MEMS circuits and devices, such as phase shifters (Barker and Rebeiz, 2000), reconfi gurable antennas and matching circuits (Brown, 1998;Ulm et al , 2003), and beam steering applications (Brown, 1998;Schoebel et al , 2005;, which are suitable for automotive radar applications. Low insertion loss, high signal linearity, high isolation, near-zero power consumption, large bandwidth of RF MEMS switches, high tuning range, low series resistance and high linearity of mechanically tunable capacitors are the advantages of these components as compared to their semiconductor equivalents.…”

“…MEMS-switched true-time delay-line (TTD) phase shifter networks (Stehle et al , 2008); 2. distributed MEMS transmission line (DMTL) phase shifters (Ulm et al , 2003); and 3. a novel concept based on tuning the loading of a 3-D micromachined transmission line by a dielectric block placed on top of the line, which is vertically moved by MEMS actuators (Somjit et al , 2009).…”

“…This effect imposes another limitation on the maximum usable capacitance ratio, in addition to those required by the switch design parameters, according to the acceptable mismatch. The capacitance ratio is reported to be limited to approximately 1.3 to 1.6 in (Ulm et al , 2003).…”

“…This alternative method provides the capability of increasing the capacitance ratio, which is more suitable in millimeter-wave regimes (Ulm et al , 2003). Barker and Rebeiz (2000) presented design and optimization of DMTL phase shifters for U-band and W-band, with analog tuning capability of the bits on quartz substrate.…”

“…These MEMS automotive-radar front-ends were developed at the University of Michigan (USA) (Van Caekenberghe and Sarabandi, 2006;Van Caekenberghe, 2009) and Robert Bosch GmbH (Germany) (Ulm et al , 2003;Schobel et al , 2005).…”