Robustness Comparison of Emerging Devices for Portable Applications

Extensive development in portable devices imposes pressing need for designing VLSI circuits with ultralow power (ULP) consumption. Subthreshold operating region is found to be an attractive solution for achieving ultralow power. However, it limits the circuit speed due to use of parasitic leakage current as drive current. Maintaining power dissipation at ultralow level with enhanced speed will further broaden the application area of subthreshold circuits even towards the field programmable gate arrays and real-time portable domain. Operating the Si-MOSFET in subthreshold regions degrades the circuit performance in terms of speed and also increases the well-designed circuit parameter spreading due to process, voltage, and temperature variations. This may cause the subthreshold circuit failure at very low supply voltage. It is essential to examine the robustness of most emerging devices against PVT variations. Therefore, this paper investigates and compares the performance of most promising upcoming devices like CNFET and DG FinFET in subthreshold regions. Effect of PVT variation on performance of CNFET and DG FinFET has been explored and it is found that CNFET is more robust than DG-FinFET under subthreshold conditions against PVT variations

Application of CSDG Mosfet based active high pass filter in communication systems.

Masters Degree. University of KwaZulu-Natal, Durban.This research work looks at the design of three active high pass filters. These filters have been designed for (i) robotic system, (ii) sensing device and (iii) satellite communication system. In this research work a high pass filter has been designed with a Cylindrical Surrounding Double Gate (CSDG) MOSFET. A CSDG MOSFET is a continuation of DG MOSFET technology. It is formed by rotation of a DG MOSFET with respect to its reference point to form a hollow cylinder. It consists of 2 gates, a drain and a source. Electronic robotic systems have a section of transmitter and receiver. For the receiver, to provide the required selectivity of frequencies, a filter is used. There is a wide variety of these filters that can be used within the Radio Frequency (RF) range. Radio frequencies range from 3 kHz to 300 GHz. This particular filter is designed and simulated at a cutoff frequency of 100 GHz (0.1 THz). It makes use both an operational amplifier and a transistor. This circuit was compared to a circuit that made use of 2 operational amplifiers and the results are discussed. In addition a CSDG MOSFET which makes use of a Silicon Dioxide dielectric is connected to the output of the transistor circuit to see what effect it has on the circuit. Using this model of filter a fine signal (command) can be given to robotic system. The second filter is designed for remote sensing devices. These devices continuously send/receive signals and these signals or radio waves are transmitted/received via a transmission line to/from a receiver/transmitter which has a filter that selectively sorts out the signals and only passes a desired range of signals. The CSDG MOSFET being a capacitive model allows for better filtering of low frequencies and passes through a frequency range of 200 GHz (0.2 THz) efficiently. By placing the capacitors in parallel, the design requires smaller capacitance values to be used. In addition the desired range of frequencies can be achieved from the inversely proportional relationship between frequency and capacitance. Finally a filter has been designed to use in satellite communication systems. These systems consist of various subsystems to allow it to function efficiently. These subsystems require a number of electronic devices. In this research work, a CSDG MOSFET is added to the output of the transistor circuit and operates within the EHF band (0.3 THz). The CSDG MOSFET makes use of Hafnium Silicate (HfSiO4) as a dielectric material due to its wide band-gap and lower dielectric constant makes it ideal for this design. The gain and other parameters of the three designed filters are analyzed. In conclusion, it has been demonstrated that the third order active high pass filters performs better with the CSDG MOSFET