Frederic Domingue

Design Methodology and Optimization of Distributed MEMS Matching Networks for Low-Microwave-Frequency Applications

A design methodology for the distributed microelectromechanical system (MEMS) impedance matching networks based on the optimization of the uniformity of the Smith chart coverage has been developed. The proposed approach was validated through a comparison between a traditional coplanar waveguide (CPW) design and an improved design based on a slow-wave (SW) structure. The enhanced reconfigurable impedance matching network has been developed for low-frequency applications. The network is based on a distributed MEMS transmission line (DMTL) coupled with the SW structure to reduce the total physical length of the network by 25% in comparison with a traditional DMTL. An extensive analysis was performed to identify the impact of each design parameter in order to optimize the structure and reduce the required size for relatively low-frequency applications. Several parameters are extracted from the electromagnetic simulation results and are used to design the proposed impedance matching network. Measurement results confirm the efficiency of the proposed design methodology in improving the impedance coverage and also miniaturization of the DMTL impedance matching networks.

Passive Microwave Substrate Integrated Cavity Resonator for Humidity Sensing

This paper presents an original passive microwave substrate integrated cavity resonator [substrate integrated waveguides (SIWs)] as an environment sensor for humidity detection. The proposed structures are based on a high quality factor (Q ~ 300) substrate integrated cavity resonator operating at 3.6 and 4.15 GHz. The detection principle is based on a frequency shift due to the permittivity variation of the humid air. This variation can be detected and used as the sensor indication. The frequency shift has been estimated analytically using the dielectric perturbation method for the resonator prototypes. The structure of the presented SIW resonators has been tested in the presence of humidity and shows sensitive characteristics in the range of 0%-80% relative humidity in accordance with the proposed model. A comparison of sensitivity performance between the new structure and other reported microwave components for environmental sensing is also presented. Measurements of repeatability and reliability for the proposed structure are discussed as well. As a new microwave component type, the proposed substrate integrated environmental sensor has the advantage of providing a new fabrication solution for radio frequency environmental sensing and greatly simplifies the sensors manufacturing processes and cost.

A novel chipless identification tag based on a substrate integrated cavity resonator

This letter presents a novel tag structure for microwave identification. The new tag is based on a high quality factor (Q=366) substrate integrated cavity resonator in which data are encoded by introducing a variation in the effective permittivity which gives a unique and identifiable frequency spectral signature. The proposed tag design operates in the frequency range of 10.5-11 GHz. The substrate integrated tag presented has the advantages of being low cost, zero power consumption, compact and can be also transferred to different types of substrates, making it suitable for many mass production applications.

A fully packaged piezoelectric switch with lowvoltage actuation and electrostatic hold

This paper reports RF characterization of a fully packaged RF MEMS piezoelectric switch. The switch demonstrates better than 0.8 dB insertion loss at 2 GHz and 30 dB isolation up to 10 GHz. The presented device combines a piezoelectric actuation and a low electrostatic hold voltage to improve contact force. Actuation voltages of the switch are 5 V for both piezoelectric actuation and electrostatic hold. This actuation was sufficient to obtain contact resistance lower than 2 ohms. The switch is packaged by wafer-level packaging technology using gap control, AuSn eutectic bonding and post-process Thru-Silicon Vias.

Distributed MEMS Tunable Impedance-Matching Network Based on Suspended Slow-Wave Structure Fabricated in a Standard CMOS Technology

A tunable RF microelectromechanical system (MEMS) impedance-matching network operating at a frequency band from 13 to 24 GHz based on the distributed microelectromechanical transmission line (DMTL) concept is presented in this paper. The network is implemented using a standard 0.35- ¿m CMOS technology and employs a novel suspended slow-wave (SSW) structure on a silicon substrate. The SSW structure results in a reduced total footprint and enhanced impedance coverage. The 8-bit DMTL matching network, fabricated using switched MEMS capacitors and SSW coplanar waveguide on a silicon substrate, results in a wide coverage of the Smith chart up to a maximum voltage standing-wave ratio of 11.5:1 with an impedance matching better than 10 dB and a power transfer ratio of better than -2.84 dB at 24 GHz. To our knowledge, this is the first implementation of a DMTL tunable MEMS impedance-matching network using a standard CMOS technology.

A reconfigurable impedance matching network using dual-beam MEMS switches for an extended operating frequency range

A reconfigurable impedance matching network has been developed for a wideband operating frequency. The network is based on a slow-wave distributed MEMS transmission line (DMTL) coupled with a tri-state MEMS capacitive switch to improve the operating frequency range. The proposed design consists of 8 tri-state RF-MEMS switches producing 6561 (38) impedance states. The size of the tunable matching network fabricated on an alumina substrate is very compact (4.4 × 1.9 mm). The measured results demonstrate wide coverage of the Smith chart between 5 GHz to 20 GHz. The transducer gain of the network is better then 1 dB for a wide range of input impedances. The measured results validate the potential of the proposed structure to realize a miniature reconfigurable matching network with a wide impedance coverage over an extended operating frequency range.

Acoustic technologies for advanced RF architectures

This paper presents different acoustic technologies available for innovative wireless designs. Solidly mounted BAW resonators, coupled resonator filters, Lamb wave devices and guided wave components are described. The advantages of these technologies are highlighted and their performances are compared. All these technologies can be used to design highly integrated wireless architectures.

Holes Effects on RF MEMS Parallel Membranes Capacitors

Parallel membrane RF MEMS capacitors are designed with small diameter holes in the top plate of capacitance due to fabrication process requirements for sacrificial layer removal and modification of dynamic behaviour of the structure. The impact of hole characteristics (size, pitch and ligament efficiency) on the component performance is not very well documented in current literature. Only rules of thumb are used in the design without giving much justification. This study explores and assesses the effect of larger holes with different pitches and ligament efficiencies in fixed top membrane by means of simulations with CoventorWare analyzer simulation software and practical probing tests conducted on specifically designed set of RF MEMS capacitors. The approach used in this study is by varying the RF capacitance with two different axis of comparison. The first being a set of MEMS capacitors having different sized holes of equal combined surface and the second having fixed number of holes with different diameters. The experimental results converge quite adequately with the designed and simulated results giving a clear performance trend and appropriate designer solution. The outcome of this paper improves the degree of freedom of the designer with respect to the manufacturing difficulties for sacrificial layer removal associated to better dynamics and RF performances of the components

Improved distributed mems matching network for low frequency applications using a slow-wave structure

A reconfigurable impedance matching network has been developed for low frequency applications. The network is based on a distributed MEMS transmission line (DMTL) coupled with a slow-wave structure to reduce the physical length of the network by 25 % in comparison with a traditional DMTL. The proposed slow-wave structure (SW-DMTL) is studied in order to validate the integration possibilities and the improvements obtained. The SW-DMTL parameters are extracted from the electromagnetic simulation results and are used to design the SW-DMTL impedance tuner. The measured impedance coverage is presented and validates the potential of the proposed structure to realize a miniature DMTL matching network with a wide impedance coverage.

Survey of commercial sensors and emerging miniaturized technologies for safety applications in hydrogen vehicles

This paper presents a study of widely commercial hydrogen-sensing technologies for automotive applications. The performed analysis of hydrogen sensors emphasizes on their advantages and weaknesses in comparison to the automotive industry requirements. Innovative and novel solutions based on the emerging miniaturized technologies which lead to higher performance and more robust hydrogen sensing are proposed and analyzed to overcome the weaknesses in the commercial sensors.