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This article reports on a low temperature cofired ceramic (LTCC)-based RF MEMS packaging and its electrical modeling using lumped elements and microstrip lines. An LTCC cap with vertical vias was flip-chip bonded with a glass substrate, where a coplanar waveguide (CPW) formed to measure the RF characteristics of packaging structure. We measured return loss (S11) and insertion loss (S21) of the fabricated packaging structure in a frequency range of 1 to 30 GHz. The parameters of two different equivalent circuits using lumped elements and physical microstrip lines were extracted from the measured results. The mean absolute errors (MAEs) were calculated to show the agreement between measured properties and electrical equivalent circuits. The calculated MAEs were 0.591 dB (S11) and 0.146 dB (S21) for lumped elements, and 0.926 dB (S11) and 0.179 dB (S21) for microstrip lines, respectively. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 252–257, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24895 [ABSTRACT FROM AUTHOR]

In this article, we proposed the novel monolithic microwave integrated circuit (MMIC) protection technique in plasma etching process for MMIC mounted mechanically movable RF MEMS antenna. We could eliminate the distortion of radiation pattern caused by RF feed line on antenna frame and torsional hinge as using MMIC direct mounting on antenna plate instead of using external RF power source. Silicon-based mechanically movable RF MEMS antenna was released using DRIE process, which was performed on the backside of silicon substrate after MMIC mounting on RF MEMS antenna plate. An aluminum layer on the front side of RF MEMS antenna plays a role of etch stop layer for DRIE process. We measured the radiation pattern as rotating the moving plate along the vertical- and horizontal-direction hinge mechanically. We could obtain the radiation pattern without gain reduction and distortion of radiation pattern. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3089–3093, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23870 [ABSTRACT FROM AUTHOR]

We developed a small-sized micromachined probe for the measurement of biological properties using microelectromechanical systems (MEMS) technology. We also experimentally showed the suitability of the micromachined probe for biological applications through in vivo, as well as in vitro measurements of various types of tissue. We measured the permittivities of 0.9% saline and the muscle and fat of pork using the micromachined probe after liquid calibration. The measured permittivities of 0.9% saline and pork agreed well with both the expected values of the Cole-Cole equation along with the measured values obtained through the use of a 1-mm-diameter open-ended coaxial probe. We also performed in vivo measurements of breast cancer tissue implanted in an athymic nude mouse to show the suitability of the small-sized micromachined probe for practical biological applications. Through the obtained data, the capability of the micromachined probe of distinguishing different tissue types from one another was shown. The actual aperture size of the micromachined probe is only 240 μm × 70 μm and, therefore, we can extract the biological information from very small biological tissues and drastically decrease the invasiveness of this method through the implementation of the small probe created through the use of MEMS technology. [ABSTRACT FROM AUTHOR]

In this paper, fully monolithic reconfigurable millimeter-wave filters are proposed using the CPW-based periodic structures with novel multiple-contact MEMS switches. Millimeter-wave low-pass and band-pass filters were designed, fabricated, and tested. Three cascaded CPW-based periodic structures, with low-pass and band-pass intrinsic filtering characteristics, are reconfigured into a self-similar single unit cell by the operation of the novel multiple-contact MEMS switches with single actuation. By using the multiple-contact MEMS switches, the insertion loss can be reduced and the operating frequency ranges are extended to millimeter-waves with little increase of loss. Additionally, the number of the switching elements has been reduced and the bias-decoupling circuits are not required, resulting in a very small chip size. The measured results of the reconfigurable low-pass filter show the 3-dB cutoff frequency change from 67 to 28 GHz with very small change in the insertion loss from 0.32 to 0.27 dB. The center frequency of the reconfigurable band-pass filter is tuned from 55 to 20 GHz, and the measured 3-dB cutoff bandwidth changed from 32 to 12 GHz, while the average insertion loss changed from 1.27 to 1.61 dB. The chip size of the low-pass and band-pass filter including dc bias line is 1.2 mm × 1.5 mm and 1.2 mm × 4.5 mm, respectively. [ABSTRACT FROM AUTHOR]

In this letter a novel λ/4 micromachined directional coupler is presented with a 10 μm benzocyclobutene (BCB) layer used to suspend one transmission line over another one in order to achieve a 3-dB coupling. The coupler is centered at a frequency of 24 GHz. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1813–1814, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22574 [ABSTRACT FROM AUTHOR]

This paper presents a theoretical and experimental strategy for thermal de-isolation of silicon microstructures during a plasma etching process. Heat sinking blocks and thin metal layers are implemented around a thermally isolated mass to avoid severe spring width losses by a steep temperature rise. Thermal de-isolation significantly reduces the fabrication errors from -51.0% to -9.0% and from -39.5% to -6.7% for spring widths and resonant frequencies, respectively. Thermal de-isolation also reduces the standard deviation of resonant frequencies from 8.7% to 1.5% across a wafer, which clearly demonstrates the proposed method. [ABSTRACT FROM AUTHOR]

Presents a type of antenna fabricated by micromachining technology for mechanical beam steering with two degrees of freedom of motion. Design of a V-band two-dimensional mechanical beam-steering antenna and fabrication on a single high-resistivity silicon substrate using microelectromechanical systems technologies; Microwave properties investigated.

Reports on the development of low-loss digital distributed phase shifters. Use of micromachined capacitive shunt switches for V-band applications; Connection of high-Q metal-air-metal capacitors in series with the microelectromechanical system; Minimization of dielectric loss; Reduction of the operation voltage for the phase shifters.