A 3-bit microelectromechanical system (MEMS) digital attenuator is designed with 0-20 GHz bandwidth. The attenuation ranges from 0 to 35 dB with 5 dB step. The attenuator, with the coplanar waveguide (CPW), is implemented by surface sacrificial layer technology. The DC-contact MEMS switches with three contact dimples are symmetrically placed around the T type resistor network, making the switches minimum in number and the structure compact. Through the lumped parameter method, the attenuator has good terminal matches in different attenuation states. The test results show that eight different attenuation states are realized within 0-20 GHz. The attenuation deviation is less than ±5%, the insertion loss is less than 1.7 dB and the voltage standing wave rations is less than 1.4 under most of the attenuation states. With the MEMS switches and CPW being adopted, the attenuator has the advantages of higher linearity, lower insertion loss and power consumption. The chip size is about 3.2 mm 2 including the pad.

Etching technique for ruthenium with a high etch rate and high selectivity using ozone gas In order to improve the temperature stability of DC-contact RF MEMS switch, a thermal buckle-beam structure is implemented. The stability of the switch pull-in voltage versus temperature is not only improved, but also the impact of stress and stress gradient on the drive voltage is suppressed. Test results show that the switch pull-in voltage is less sensitive to temperature between -20 • C and 100 • C. The variable rate of pull-in voltage to temperature is about -120 mV/ • C. The RF performance of the switch is stable, and the isolation is almost independent of temperature. After being annealed at 280 • C for 12 hours, our switch samples, which are suitable for packaging, have less than 1.5% change in the rate of pull-in voltage. C 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License. [http://dx Design of DC-contact RF MEMS switch with temperature stability

This paper presents a high reliable direct-contact electrostatic RF MEMS switch. To enhance the reliability, the contact structure of the switch is designed into a circular shape, and the bottom contact surface is covered by a hard metal Pt layer. Besides, a high resistance silicon cap is used for hermetic packaging of the switch structure. By theoretical calculation and FEM simulation, parameters of the switch structure as well as its packaging are co-designed and optimized. During fabrication, the circular contact structure is formed by a three-step etching process; and after fabrication, the silicon hermetic packaging is realized by epoxy bonding and multi-step dicing process. The measured insertion loss and isolation of the switch with package is -0.41@ 20GHz, and -20.9@20GHz. Because of the optimization design, the RF performance of the switch keeps almost unchanged before and after packaging. The measured driving voltage is 50~60V, and the ON/OFF switching time is 25μs/5μs. The lifetime test shows that the switch passes the 2.6 billion times hot switching at the working power of 25 dBm. Finally, the switch also shows good performances in package leak rate test.

This paper describes a novel monolithic switchable filter covering a bandpass frequency of 12–16 GHz at the Ku-band on a silicon substrate. The filter structure is based on parallel-coupled half-wavelength resonator topologies and microelectromechanical system-tunable resonators designed by placing ohmic switches at the open ends of the microstrip resonators. A wideband coplanar waveguide is designed for microstrip transition without via holes during wafer testing. The measured results show a minimum insertion loss of 3.6 dB, a return loss better than 15 dB, a 10.2% fractional bandwidth and a 14.2% tuning range from 13 to 15 GHz. The fabricated filter has a chip area of 15.1 mm × 3 mm and has achieved skirt slopes of over 30 dB GHz−1.