CMOS Signal Synthesizers for Emerging RF-to-Optical Applications

The need for clean and powerful signal generation is ubiquitous, with applications spanning the spectrum from RF to mm-Wave, to into and beyond the terahertz-gap. RF applications including mobile telephony and microprocessors have effectively harnessed mixed-signal integration in CMOS to realize robust on-chip signal sources calibrated against adverse ambient conditions. Combined with low cost and high yield, the CMOS component of hand-held devices costs a few cents per part per million parts. This low cost, and integrated digital processing, make CMOS an attractive option for applications like high-resolution imaging and ranging, and the emerging 5-G communication space. RADAR techniques when expanded to optical frequencies can enable micrometers of resolution for 3D imaging. These applications, however, impose upto 100x more exacting specifications on power and spectral purity at much higher frequencies than conventional RF synthesizers. This generation of applications will present unconventional challenges for transistor technologies - whether it is to squeeze performance in the conventionally used spectrum, already wrung dry, or signal generation and system design in the relatively emptier mm-Wave to sub-mmWave spectrum, much of the latter falling in the ``Terahertz Gap". Indeed, transistor scaling and innovative device physics leading to new transistor topologies have yielded higher cut-off frequencies in CMOS, though still lagging well behind SiGe and III-V semiconductors. To avoid multimodule solutions with functionality partitioned across different technologies, CMOS must be pushed out of its comfort zone, and technology scaling has to have accompanying breakthroughs in design approaches not only at the system but also at the block level. In this thesis, while not targeting a specific application, we seek to formulate the obstacles in synthesizing high frequency, high power and low noise signals in CMOS and construct a coherent design methodology to address them. Based on this, three novel prototypes to overcome the limiting factors in each case are presented. The first half of this thesis deals with high frequency signal synthesis and power generation in CMOS. Outside the range of frequencies where the transistor has gain, frequency generation necessitates harmonic extraction either as harmonic oscillators or as frequency multipliers. We augment the traditional maximum oscillation frequency metric (fmax), which only accounts for transistor losses, with passive component loss to derive an effective fmax metric. We then present a methodology for building oscillators at this fmax, the Maximum Gain Ring Oscillator. Next, we explore generating large signals beyond fmax through harmonic extraction in multipliers. Applying concepts of waveform shaping, we demonstrate a Power Mixer that engineers transistor nonlinearity by manipulating the amplitudes and relative phase shifts of different device nodes to maximize performance at a specific harmonic beyond device cut-off. The second half proposes a new architecture for an ultra-low noise phase-locked loop (PLL), the Reference-Sampling PLL. In conventional PLLs, a noisy buffer converts the slow, low-noise sine-wave reference signal to a jittery square-wave clock against which the phase of a noisy voltage-controlled oscillator (VCO) is corrected. We eliminate this reference buffer, and measure phase error by sampling the reference sine-wave with the 50x faster VCO waveform already available on chip, and selecting the relevant sample with voltage proportional to phase error. By avoiding the N-squared multiplication of the high-power reference buffer noise, and directly using voltage-mode phase error to control the VCO, we eliminate several noisy components in the controlling loop for ultra-low integrated jitter for a given power consumption. Further, isolation of the VCO tank from any varying load, unlike other contemporary divider-less PLL architectures, results in an architecture with record performance in the low-noise and low-spur space. We conclude with work that brings together concepts developed for clean, high-power signal generation towards a hybrid CMOS-Optical approach to Frequency-Modulated Continuous-Wave (FMCW) Light-Detection-And-Ranging (LIDAR). Cost-effective tunable lasers are temperature-sensitive and have nonlinear tuning profiles, rendering precise frequency modulations or 'chirps' untenable. Locking them to an electronic reference through an electro-optic PLL, and electronically calibrating the control signal for nonlinearity and ambient sensitivity, can make such chirps possible. Approaches that build on the body of advances in electrical PLLs to control the performance, and ease the specification on the design of optical systems are proposed. Eventually, we seek to leverage the twin advantages of silicon-intensive integration and low-cost high-yield towards developing a single-chip solution that uses on-chip signal processing and phased arrays to generate precise and robust chirps for an electronically-steerable fine LIDAR beam

FORMULATION AND EVALUATION OF COLON TARGETED DRUG DELIVERY SYSTEM OF BUSULFAN: USING COMBINATION OF pH AND TIME DEPENDANT SYSTEMS

In present work Colon targeting drug delivery system was developed for Busulfan an anticancer drug by using combination of delayed systems one is pH dependant and other is time dependant delayed system.  Rapid release core tablet (RRCT) formulations were prepared using Busulfan drug with different disintegrating agents in different concentrations. The pre-compression and post-compression parameters of all formulations were determined and the values were found to be satisfactory. From the In-vitro dissolution studies, F6 formulation with 12% Hydroxy propyl cellulose (HPC) was the best formulation. For optimized RRCT formulation press coat was done by using Xanthum Gum and Ethyl Cellulose (EC) in different ratios. Press coated tablet delays the drug release up to 8 hours based on the nature and concentrations of the polymer. Each press coated tablet was coated using enteric solution made of HPMC phthalate, Myvacet and color dissolved in ethanol. Enteric press coated tablets (EPCT) were delayed drug release up to 2hrs in fed condition due to pH dependant delayed system.  Based on dissolution studies of EPCT formulations, C3OPF formulation was optimized and showed delayed release pattern in a much customized manner. As a result of this study it may be concluded that the colon targeted drug delivery tablets using a combination of two polymers in optimized concentrations can be used to increase the delayed action of drug release to deliver the drug in a delayed manner. Key words: Colon, RRCT, HPC, Xanthum gum and EPC

Wind Power Control Using MPPT and SEPIC Converter

A wind energy system is simulated by MATLAB/SIMULINK software. In which a SEPIC (DC/DC converter) converter is used to convert the varingDC voltage a constant output voltage by using its control mechanism.The amount of power output from a Wind Energy System (WES) depends upon the accuracy with which the peak power points are tracked by the maximum power point tracking (MPPT) controller of the WES control system irrespective of the type of generator used. Incremental conductance (InCond) method has been used as the algorithm in this MPPT block. The simulated system proposed uses a three-level, three phase, twelve pulse inverter for converting DC voltage generated by the SEPIC converter to AC voltage at desired frequency and voltage level. The usage of three-level inverter reduces Total Harmonic Distortion (THD) in output voltage. When large power generated from wind energy system then it will be stored in Battery, this stored energy will be used by load when system is shut-down or in unrealiable conditions. Lead-acid batteries are used due to their large availability in many sizes, low cost and well firm performance characteristics. The main concentration here is to develop a system to make use of the available renewable resourcei.eWES effectively and increase the efficiency of system by implementing MPPT technique

Poliovirus Excretion in Children with Primary Immunodeficiency Disorders, India

Prolonged excretion of poliovirus can occur in immunodeficient patients who receive oral polio vaccine, which may lead to propagation of highly divergent vaccine-derived polioviruses (VDPVs), posing a concern for global polio eradication. This study aimed to estimate the proportion of primary immunodeficient children with enterovirus infection and to identify the long-term polio/nonpolio enterovirus excreters in a tertiary care unit in Mumbai, India. During September 2014–April 2017, 151 patients received diagnoses of primary immunodeficiency (PID). We isolated 8 enteroviruses (3 polioviruses and 5 nonpolio enteroviruses) in cell culture of 105 fecal samples collected from 42 patients. Only 1 patient with severe combined immunodeficiency was identified as a long-term VDPV3 excreter (for 2 years after identification of infection). Our results show that the risk of enterovirus excretion among children in India with PID is low; however, systematic screening is necessary to identify long-term poliovirus excreters until the use of oral polio vaccine is stopped