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In this paper, a dual-mode (DM) micromechanical elliptical ring resonator for use in temperature sensing is reported. The proposed resonator is made of single crystal silicon and works based on beat frequency (fb). In the designed sensor, temperature coefficient of beat frequency (TCfb) will be increased significantly by minimizing the fb and provides better temperature sensitivity. This proposed device was designed and simulated by COMSOL Multyphysics software. By engineering the device geometry, we introduce two adjacent resonant frequencies which produce very small fb in the range of 2 kHz. The device shows TCf1 of about 44 ppm/ºC and TCf2 of 5 ppm/ºC. Combination of small fb and large ΔTCf, present temperature coefficient of beat frequency (TCfb) about 112000 ppm/ºC which has approximately 75× improvement in TCfb compared to previous demonstrated DM resonators. [ABSTRACT FROM AUTHOR]

In this paper design and simulation of an improved depletion-mode n-channel nanoelectromechanical field effect transistor (NEMFET) at 300K is reported. The designed NEMFET is based on NEMS technology and fully compatible with CMOS fabrication process. A NEMFET is composed of a NEM relay and a MOSFET and comprises a movable gate and a semiconductor part, so that the flowing current is always in the semiconductor part. The nanomechanical movable gate was a bossed doubly clamped beam and simulated by COMSOL Multiphysics software and the electrical part was designed and simulated by ATLAS software. The designed NEMFET had a 25 nm length, 100 nm width and 5.2 nm thicknesses. Optimization was done by applying two 8.5 nm spaces, one between source to gate and the other between gate to drain. Simulation results show in the proposed structure, sub-threshold swing was decreased to 86 mV/dec and the Ion/Ioff ratio was increased to 8.68×104. [ABSTRACT FROM AUTHOR]

In this paper, an operational transconductance amplifier (OTA) is designed, simulated and configured so that input dynamic range is improved by bulk-driven technique of the input transistors. The bulk-driven structure is used in the proposed OTA to stabilize the transconductance and to achieve a high linearity. By changing the control voltage and the input common-mode voltage, the voltages and currents of the circuit are changed so that the transconductance and the voltage gain are changed linearly. Also, setting a reference voltage in the circuit can greatly reduce the destructive effects of undesired changes in the circuit operation during fabrication process. The proposed OTA is designed in 180 nm CMOS technology and required only 0.5 V supply voltage. The simulation results show the OTA voltage gain is varied from 0 dB to 14.2 dB by changing the control voltage from 0 to 0.5 V. Moreover, the input common-mode voltage of the OTA can be changed in the range of 0.125 to 0.375V and without linear degradation. The proposed OTA is dissipated 250 nW and makes it suitable for low-power applications. [ABSTRACT FROM AUTHOR]