R. Joseph Daniel

Low Actuation Voltage RF MEMS Switch Using Varying Section Composite Fixed-Fixed Beam

The present authors have earlier reported the employment of varying section fixed-fixed beam for achieving lower pull-in voltage with marginal fall in restoring force. Reducing Young’s modulus also reduces the pull-in voltage but with lesser degree of reduction in restoring force. Composite beams are ideal alternatives to achieve decreased Young’s modulus. Hence new varying section composite fixed-fixed beam type RF MEMS switch has been proposed. The main advantage of this RF MEMS switch is that lower pull-in voltages can be achieved with marginal fall in stiction immunity. Spring constant of the proposed switch has been obtained using simulation studies and it has been shown that the spring constant and therefore the pull-in voltage ( ) can be considerably reduced with the proposed switch. Simulation studies conducted on the proposed switch clearly demonstrate that the pull-in voltage can be reduced by 31.17% when compared to the varying section monolayer polysilicon fixed-fixed beam. Further this approach enables the designer to have more freedom to design lower pull-in voltage switches with improved stiction immunity.

Design of Stictionfree - Lower Pull in Voltage RF MEMS Switch Using Varying Section Cantilever Beam

A new varying section cantilever beam type RF MEMS switch has been proposed. The main advantage of this switch is that it is inherently stiction free and therefore enhances design flexibility. An analytical model developed using unit load approach for the spring constant of the proposed switch has been presented and it has been shown that the spring constant and therefore the pull in voltage (Vpi) can be considerably reduced with the proposed switch. Simulation studies conducted on two groups of devices clearly demonstrate that the pull in voltage can be reduced by 26% with ten sections. Comparision of the pull in voltage obtained in the simulation studies for devices with the theoretically estimated Vpi shows that the spring constant model presented in this paper accurately estimates the spring constant. The results of analytical studies also demonstrate that the new proposed cantilever beam can considerably reduce the pull in voltage.

Sensitivity enhancement by striped arrow embossed diaphragms in low pressure MEMS piezoresistive pressure sensors

Design of low pressure MEMS sensors with high sensitivity and excellent linearity is a challenge. Researchers have proposed different techniques to achieve this. The authors propose broken arrow embossed diaphragms for the design of low range pressure sensors based on piezoresistive effect. Studies on these sensor structures show that these diaphragms are able to generate larger stresses than flat diaphragm thus enhancing the sensitivity considerably. They also perform better than the structures studied by other researchers in the past. This study also demonstrates that the proposed structure is also capable of maintaining high degree of linearity.

Graphene interconnect for nano scale circuits

The role of interconnect in an integrated circuit is to enable effective passing of clock and other signals in addition to providing power to various parts of the circuit on a chip. The advent of sub-quarter-micron IC technologies has forced dramatic changes in the design and manufacturing methodologies for integrated circuits and systems. The paradigm shift for interconnect which was once considered just parasitic but can now be a dominant factor for integrated circuit performance provided the greatest impetus for change of existing methodologies. Copper, which is presently used as the interconnect material. Cu interconnect dimensions begin to come into the range of mean free path of electron typically 40nm. This results in surface and grain boundary scattering. Owing to these scattering phenomena resistivity, of Cu begins to increase. This limitation of copper interconnects is driving research for alternative interconnect materials and technologies for next-generation ICs. Nanotubes, Graphene, and Nanowires and Carbon Nano Tubes are some of the new materials suggested as an alternate to overcome these problems. Here in this paper we have analysed the various properties of graphene to use as an interconnect. Graphene has been attracting wide attention owing to its superb electronic, thermal and mechanical properties.

Design of High Sensitivity SOI Piezoresistive MEMS Pressure Sensor

In this paper, the effect of the size of the piezoresistors that forms the Wheatstone bridge on sensitivity has been studied and reported. There are four resistors implanted on the diaphragm in such a way that two of them sense the tensile stress (Group I) and the other two senses the compressive stresses (Group II). The structure of this MEMS sensor has been created and analyzed using IntelliSuite MEMS CAD tool. The results show that the size of the group I resistors should be made as large as possible and that of group II should be made as small as possible to achieve maximum sensitivity. It is also illustrated that the size design of group II resistors is critical.