Christian Siegel

Simplified RF-MEMS Switches Using Implanted Conductors and Thermal Oxide

This paper presents microwave capacitive RF-MEMS switches based on a novel simplified fabrication process. The devices are fabricated on a silicon substrate using only one metallisation layer. For the capacitive coupling of the switch, an implanted conductive region and thermally grown silicon oxide is used instead of a second metal layer and an additional dielectric layer. In addition, the formerly used bimorph metallisation layer is replaced by a single-metallisation concept, which results in an increased temperature range of operation. The simplified process as well as the switch topology used lead to high performance and highly reliable RF-MEMS switches. RF-measurement results are presented of Ku- and K-band series switches and a Ka-band parallel switch with low insertion losses between -0.2dB and -0.3dB and isolation of e.g. -17dB at 30GHz

Very low complexity RF-MEMS technology for wide range tunable microwave filters

This paper presents tunable microstrip filters in the GHz range, fabricated on silicon in a very low complexity RF-MEMS process with only one metallization layer. Affected by a mechanic stress gradient in the metallization, free standing parts of the structure roll up. These bended beams can be switched onto the substrate by electrostatic actuation and thus tune the resonance frequency by changing the /spl epsiv//sup r eff/ of the resonant structure. The technology offers the possibility to realize tunable filters with a small insertion loss of less than 1.5dB at 30GHz for bandpass and for bandstop filters and a large frequency shift of about 20% in operation frequency.

Hybrid Integrated RF-MEMS Phased Array Antenna at 10GHz

In this paper, a one-dimensional electrically steerable RF-MEMS phased array antenna for operation at 9.5 GHz is demonstrated. The antenna itself is a four by eight patch antenna array realised on low-loss Teflon substrate and the feed network made out of the same substrate is a one-to-four corporate feed network. The phase shifting necessary to steer the main beam of the antenna in the H-plane of the aperture is achieved by four 3 bit RF-MEMS phase shifters, which are integrated in a hybrid fashion between the antenna and the feed network. The paper describes the integration of the different elements in a standalone phased array antenna demonstrator. The design of the 3 bit RF-MEMS phase shifters is presented and validated by very good measurement results. Finally, the measured radiation characteristic of the complete phased array antenna is shown for different switching states of the phase shifters.

Low complexity RF-MEMS switch optimized for operation up to 120°C

This paper presents a RF-MEMS switch optimized for high temperature range of operation using a temperature stable metallization. The devices are fabricated on a silicon substrate in very low complexity process using only one metallization. The performed measurements characterize the properties of the metallization and also the properties of the entire switch in terms of creeping behaviour, RF performance and charging effects at different temperatures. A stable operation up to 120degC is demonstrated and the principle reliability of the switches is shown by 109 switching cycles.

Chip scale package of a MEMS microphone and ASIC stack

Most MEMS microphone systems on the market are packaged by conventional chip bonding and wire bonding.. A significant step towards miniaturization was achieved earlier by applying flip-chip bonding to MEMS microphone packaging. This technology is called chip scale MEMS package (CSMP). Thereby the package size could be reduced to 2.8 × 2.05 × 0.9 mm³ compared to a standard size of 3.76 × 2.95 × 1.1 mm³. In this paper the next step in miniaturization is presented. A further reduction to a total size of only 2.05 × 2.05 × 0.95 mm³ was achieved by placing the ASIC directly under the microphone chip inside a cavity in the substrate. This design is called stacked CSMP.

Switchable microwave circuits using the EADS low-complexity RF-MEMS process

This article illustrates the ongoing RF-MEMS development at EADS Innovation Works in Germany from the basic drivers for the use of RF-MEMS in aeronautic and space systems to the major results achieved so far. It discusses in detail the EADS low-complexity RF-MEMS in-house process and highlights the demonstration of several switchable microwave circuits like phase shifters, filters and patch antennas. Index Terms – RF-MEMS, switch, switchable filter, switchable antenna, low-complexity, technology