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This paper reports a low-dispersion metamaterial-based 3-bit phase shifter which occupies an area of approximately 5 mm2 and uses only six microelectromechanical systems (MEMS) switches. The phase shifter is based on a coplanar slow-wave structure with defected ground and comprises three unit cells of 180°, 90° and 45° phase shifts, respectively. Each unit cell uses two single-pole-single-throw MEMS...
This paper reports compact, wideband, low-dispersion, metamaterial-based phase shifters with lower loss, wider bandwidth, and fewer MEMS switches than previous designs. The present design is based on a novel 90° unit cell which uses two synchronized MEMS switches that are actuated and unactuated in unison for the through and delayed states, respectively. By combining three of these 90° unit cells...
Novel phase shifters were designed by using only two MEMS switches to control a metamaterial-based slow-wave structure in each unit cell. A unit cell with an area smaller than 1 mm2 exhibited a phase shift of 54±15°, an insertion loss of less than 0.9 dB, and a return loss of higher than 15 dB between 12 GHz and 18GHz. Modeling not only agrees with the measured data, but also points out possibilities...
This paper reviews the progress over the past decade in improving the reliability of MEMS capacitive switches. The emphasis is on mitigating the dielectric-charging problem as it currently limits the lifetime of these switches. The most critical is to distinguish charging of the dielectric surface from that of the dielectric bulk, and then mitigate them separately. Once surface charging is eliminated...
We report, for the first time, the benefit of RF burn-in at power levels significantly higher than the nominal handling capacity of micro-electromechanical capacitive switches. The benefit appears to be permanent, so that, after burn-in, the switches remain less vulnerable to dielectric charging and, presumably, more reliable. It was speculated that high RF power permanently changed the bond configuration...
A CMOS control circuit capable of closed-loop capacitance sensing and control of RF MEMS switches was designed, fabricated, and tested. The control was based on fine-tuning the magnitude of the bias voltage of the switches according to the difference between sensed and targeted capacitances. Intelligence could be programmed by periodically alternating the sign of the bias voltage when its magnitude...
Modifications to a standard capacitive MEMS switch process have been made to allow the incorporation of ultra-nano-crystalline diamond as the switch dielectric. The impact on electromechanical performance is minimal. However, these devices exhibit uniquely different charging characteristics, with charging and discharging time constants 5-6 orders of magnitude quicker than conventional materials. This...
A robust design of RF MEMS capacitive shunt switches was implemented with a movable gold membrane, separate and non-contacting actuation pads, and electrostatic actuation. The same design was fabricated on silicon and quartz substrates with different combinations of dielectric constant, resistivity, thermal conductivity, and thermal expansion coefficient. It was found that most switches could operate...
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