Design and implementation of frequency synthesizers for 3-10 ghz mulitband ofdm uwb communication

The allocation of frequency spectrum by the FCC for Ultra Wideband (UWB) communications in the 3.1-10.6 GHz has paved the path for very high data rate Gb/s wireless communications. Frequency synthesis in these communication systems involves great challenges such as high frequency and wideband operation in addition to stringent requirements on frequency hopping time and coexistence with other wireless standards. This research proposes frequency generation schemes for such radio systems and their integrated implementations in silicon based technologies. Special emphasis is placed on efficient frequency planning and other system level considerations for building compact and practical systems for carrier frequency generation in an integrated UWB radio. This work proposes a frequency band plan for multiband OFDM based UWB radios in the 3.1-10.6 GHz range. Based on this frequency plan, two 11-band frequency synthesizers are designed, implemented and tested making them one of the first frequency synthesizers for UWB covering 78% of the licensed spectrum. The circuits are implemented in 0.25µm SiGe BiCMOS and the architectures are based on a single VCO at a fixed frequency followed by an array of dividers, multiplexers and single sideband (SSB) mixers to generate the 11 required bands in quadrature with fast hopping in much less than 9.5 ns. One of the synthesizers is integrated and tested as part of a 3-10 GHz packaged receiver. It draws 80 mA current from a 2.5 V supply and occupies an area of 2.25 mm2. Finally, an architecture for a UWB synthesizer is proposed that is based on a single multiband quadrature VCO, a programmable integer divider with 50% duty cycle and a single sideband mixer. A frequency band plan is proposed that greatly relaxes the tuning range requirement of the multiband VCO and leads to a very digitally intensive architecture for wideband frequency synthesis suitable for implementation in deep submicron CMOS processes. A design in 130nm CMOS occupies less than 1 mm2 while consuming 90 mW. This architecture provides an efficient solution in terms of area and power consumption with very low complexity

Study on Rheological Properties of Sodium Carboxymethyl Cellulose in the presence of mixed surfactants and Electrolytes

The effect of mixed surfactant systems of CTAB (cationic) and IGEPAL – CO 890 (non ionic) as well as different electrolytes i.e. NaCl, Na2SO4, and NaH2PO4 on the flow rheological properties of CMC has been studied. Initially various properties such as CMC values, surface excess, β interaction parameter and area of the molecule are calculated for mixed surfactant systems in the ratio of 7:3 and 3:7 (CTAB to IGEPAL CO -890) and also in the presence of electrolytes at 150mmol at low value of mixed surfactants. Low values of CMC were observed for mixed surfactant systems due to higher synergistic effect and minimum surface tension value is also low for the mixed surfactant solution compared to that of the pure surfactants. Later flow rheological properties of carboxymethyl cellulose i.e. change in viscosity and shear stress for a wide range of shear rate in the presence of surfactants and electrolytes were observed. It was observed that at low shear rate viscosity values were higher and with increasing shear rate the values decreases. It was also observed that with increase in surfactant values and valency of electrolytes the shear stress decreases due to adsorption of surfactant molecules in between the polymer molecules which results in disruption of the structured molecule

Design and implementation of frequency synthesizers for 3-10 ghz mulitband ofdm uwb communication

The allocation of frequency spectrum by the FCC for Ultra Wideband (UWB) communications in the 3.1-10.6 GHz has paved the path for very high data rate Gb/s wireless communications. Frequency synthesis in these communication systems involves great challenges such as high frequency and wideband operation in addition to stringent requirements on frequency hopping time and coexistence with other wireless standards. This research proposes frequency generation schemes for such radio systems and their integrated implementations in silicon based technologies. Special emphasis is placed on efficient frequency planning and other system level considerations for building compact and practical systems for carrier frequency generation in an integrated UWB radio. This work proposes a frequency band plan for multiband OFDM based UWB radios in the 3.1-10.6 GHz range. Based on this frequency plan, two 11-band frequency synthesizers are designed, implemented and tested making them one of the first frequency synthesizers for UWB covering 78% of the licensed spectrum. The circuits are implemented in 0.25µm SiGe BiCMOS and the architectures are based on a single VCO at a fixed frequency followed by an array of dividers, multiplexers and single sideband (SSB) mixers to generate the 11 required bands in quadrature with fast hopping in much less than 9.5 ns. One of the synthesizers is integrated and tested as part of a 3-10 GHz packaged receiver. It draws 80 mA current from a 2.5 V supply and occupies an area of 2.25 mm2. Finally, an architecture for a UWB synthesizer is proposed that is based on a single multiband quadrature VCO, a programmable integer divider with 50% duty cycle and a single sideband mixer. A frequency band plan is proposed that greatly relaxes the tuning range requirement of the multiband VCO and leads to a very digitally intensive architecture for wideband frequency synthesis suitable for implementation in deep submicron CMOS processes. A design in 130nm CMOS occupies less than 1 mm2 while consuming 90 mW. This architecture provides an efficient solution in terms of area and power consumption with very low complexity

Design and implementation of low power multistage amplifiers and high frequency distributed amplifiers

The advancement in integrated circuit (IC) technology has resulted in scaling down of device sizes and supply voltages without proportionally scaling down the threshold voltage of the MOS transistor. This, coupled with the increasing demand for low power, portable, battery-operated electronic devices, like mobile phones, and laptops provides the impetus for further research towards achieving higher integration on chip and low power consumption. High gain, wide bandwidth amplifiers driving large capacitive loads serve as error amplifiers in low-voltage low drop out regulators in portable devices. This demands low power, low area, and frequency-compensated multistage amplifiers capable of driving large capacitive loads. The first part of the research proposes two power and area efficient frequency compensation schemes: Single Miller Capacitor Compensation (SMC) and Single Miller Capacitor Feedforward Compensation (SMFFC), for multistage amplifiers driving large capacitive loads. The designs have been implemented in a 0.5??m CMOS process. Experimental results show that the SMC and SMFFC amplifiers achieve gain-bandwidth products of 4.6MHz and 9MHz, respectively, when driving a load of 25Kδ/120pF. Each amplifier operates from a ??1V supply, dissipates less than 0.42mW of power and occupies less than 0.02mm2 of silicon area. The inception of the latest IEEE standard like IEEE 802.16 wireless metropolitan area network (WMAN) for 10 -66 GHz range demands wide band amplifiers operating at high frequencies to serve as front-end circuits (e.g. low noise amplifier) in such receiver architectures. Devices used in cascade (multistage amplifiers) can be used to increase the gain but it is achieved at an expense of bandwidth. Distributing the capacitance associated with the input and the output of the device over a ladder structure (which is periodic), rather than considering it to be lumped can achieve an extension of bandwidth without sacrificing gain. This concept which is also known as distributed amplification has been explored in the second part of the research. This work proposes certain guidelines for the design of distributed low noise amplifiers operating at very high frequencies. Noise analysis of the distributed amplifier with real transmission lines is introduced. The analysis for gain and noise figure is verified with simulation results from a 5-stage distributed amplifier implemented in a 0.18??m CMOS process

Institutional quality and foreign direct investment inflows : evidence from cross-country data with policy implication

Purpose: The study examines the impact of institutional quality on Foreign Direct Investment (FDI) inflows for emerging economies from South Asiain the period 2002-2016. Other economic factors such as globalisation, financial development, and GDP are also considered. Design/Methodology/Approach: The study uses Im-Pesaran-Shin (IPS) panel unit root test to check stationarity property. It uses cross dependency (CD) and cross-sectional augments IPS tests to check cross-sectional dependency and heterogeneity across the group countries. Next, it uses panel ARDL-PMG tests to check the existence of long-relationship among variables. Then, we apply the panel Granger causality test to check the direction of causality. Finally, for the robustness of results, we use the Pedroni co-integration technique. Findings: The study finds the existence of a long-run relationship between institutional quality and FDI inflows. Other economic factors such as globalization and financial development show long-run and strong causality with FDI inflows. However, the short-run unidirectional causality from institutional quality to FDI inflows is not found for all the countries. Finally, institutional quality strongly causes FDI inflows provided paired with either globalisation or financial development. Practical Implications: Institutional quality increases the FDI inflows. Therefore, policymakers should focus on institutional quality along with globalization and financial development for higher inflows of FDI in emerging countries. Originality/Value: The study considers institutional quality as one of the inputs for FDI inflows in selected emerging economies from South Asia. Further, it creates an institutional quality index for the emerging countries to examine the impact on FDI inflows.peer-reviewe

A System for the Generation of Synthetic Wide Area Aerial Surveillance Imagery

The development, benchmarking and validation of aerial Persistent Surveillance (PS) algorithms requires access to specialist Wide Area Aerial Surveillance (WAAS) datasets. Such datasets are difficult to obtain and are often extremely large both in spatial resolution and temporal duration. This paper outlines an approach to the simulation of complex urban environments and demonstrates the viability of using this approach for the generation of simulated sensor data, corresponding to the use of wide area imaging systems for surveillance and reconnaissance applications. This provides a cost-effective method to generate datasets for vehicle tracking algorithms and anomaly detection methods. The system fuses the Simulation of Urban Mobility (SUMO) traffic simulator with a MATLAB controller and an image generator to create scenes containing uninterrupted door-to-door journeys across large areas of the urban environment. This ‘pattern-of-life’ approach provides three-dimensional visual information with natural movement and traffic flows. This can then be used to provide simulated sensor measurements (e.g. visual band and infrared video imagery) and automatic access to ground-truth data for the evaluation of multi-target tracking systems

Do a Robot's Eyes Change a Human's Speech?

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Do a Robot's Eyes Change a Human's Speech?

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Does a robot’s gaze aversion affect human gaze aversion?

Gaze cues serve an important role in facilitating human conversations and are generally considered to be one of the most important non-verbal cues. Gaze cues are used to manage turn-taking, coordinate joint attention, regulate intimacy, and signal cognitive effort. In particular, it is well established that gaze aversion is used in conversations to avoid prolonged periods of mutual gaze. Given the numerous functions of gaze cues, there has been extensive work on modelling these cues in social robots. Researchers have also tried to identify the impact of robot gaze on human participants. However, the influence of robot gaze behavior on human gaze behavior has been less explored. We conducted a within-subjects user study (N = 33) to verify if a robot’s gaze aversion influenced human gaze aversion behavior. Our results show that participants tend to avert their gaze more when the robot keeps staring at them as compared to when the robot exhibits well-timed gaze aversions. We interpret our findings in terms of intimacy regulation: humans try to compensate for the robot’s lack of gaze aversion.Peer Reviewe