Low LC Research Articles

Cascaded H-Bridge Inverters for UPS Applications: Adaptive Backstepping Control and Formal Stability Analysis

In this letter, an advanced adaptive controller is designed for N-cascaded H-bridge multilevel inverters, each fed by a DC voltage source. The studied system provides an added-value to Uninterruptable Power Supply applications, and is able to generate a precise sinusoidal voltage using a low dimensional LC filter. The main objectives of this letter are: i. generating a low THD sinusoidal voltage, ii. developing adaptive control laws able to regulate the system even with the presence of parameters' variations, and iii. proving the stability of the designed system using some tools from Lyapunov stability, Lasalle's invariance principle and persistency of excitation. This latter proves that the closed-loop control system is uniformly exponentially stable. To achieve these objectives, the adaptive backstepping approach is used. The performance of the system is checked with the use of MATLAB/SIMULINK/ SimPowerSystems environment, where the synthesized regulator meets its objectives.

Increasing power efficiency in the design of a low power and low phase noise CMOS LC oscillator

SummaryThis study developed a local oscillator (LO) with low phase noise and low power consumption. The proposed oscillator core comprises a pair of cross‐coupled transistors, which are fed by another pair of transistors that injects current at moments close to the peak of output voltage. The position of the current injection transistors, which are inserted in series with the cross‐coupled transistors, affects the waveform of current injected into an inductive–capacitive (LC) tank. Installing a capacitor on the source node of the cross‐coupled transistors increases the current injected into the LC tank and thereby augments the output voltage amplitude and power efficiency of the LO. The resonator phase shift and Q can be corrected by adjusting the source capacitance, which filters noise. These changes reduce the phase noise to −123.4 dBc/Hz at a frequency offset of 1 MHz and improve oscillator performance with a figure of merit equal to −193.5 dBc/Hz. To evaluate the LC tank, a 5 GHz LO was simulated at 1.8 V power supply and 2.5 mW power consumption. The simulation was conducted using a practical 0.18 complementary metal–oxide–semiconductor model manufactured by the Taiwan Semiconductor Manufacturing Company. The simulation results confirmed the analytical findings.

Study of the Greitzer Model for Centrifugal Compressors: Variable Lc Parameter and Two Types of Surge

In this paper, the Greitzer surge model was systematically analysed with the model compressor duct length Lc as the tuning parameter. The surge phenomenon is known to induce a serious risk to centrifugal compressor operation. The two-dimensional Greitzer model is a well-established way of modelling this dangerous instability, but the determination and changes of the model parameters are still being discussed. In this paper an automated procedure determines the Lc value providing the best fit with the experimental data has been presented. The algorithm was tested on five valve positions and revealed that the best fit was obtained for different Lc values following a linear trend against the mass flow rate. The study has also shown that the Greitzer model has two solutions for a given pressure oscillation amplitude: one similar to the deep surge (low Lc) and one similar to the mild surge (low Lc). This suggests that this model can be used to simulate both types of the phenomenon known from the experimental analyses. The study proposes the dimensionless average pressure as the parameter allowing to distinguish which surge cycle was observed at a given instance. Past papers were analysed to observe the surge type that appeared in different experiments. It was found that most researchers obtained low Lc surge. The results show that both deep and mild surge could be simulated with the Greitzer model. It also revealed that the Lc should not be treated as a constant value for a given machine and that it changes with the mass flow rate.

Power conversion with complete photonic band gap in magneto-photonic crystal slab based on cerium-substituted yttrium iron garnet

Abstract In this work, we propose a slab waveguide structure based on a magneto-photonic crystal, formed by a triangular lattice of circular air holes in a cerium-substituted yttrium iron garnet (Ce-YIG) medium grown on a silica (SiO2) substrate; in this structure, we have studied the width of the photonic band gap (PBG) using the expansion plane waves method in three dimensions to reach and optimize the complete PBG, centered at the telecommunication wavelength, also a theoretical study of the conversion mode, reported and studied the effect of some parameters such as the radius and the thickness using a beam propagation method in two dimensions. In our proposed structure, the maximum conversion modes ratio equal to 98% with a low coupling length LC = 15 µm is obtained for gyrotropy g = 0.36 and Faraday rotation FR = 1500 × 104 deg/cm.

Performance Analysis of Unipolar SPWM Inverter: Resistive load and Inductive load

This paper presents the performance analysis of the Unipolar SPWM Inverter for the resistive and inductive load testing. The common criteria reported in various technical papers where the resistive load will produce a unity power factor correction and lagging power factor behaviour for inductive load. This paper is to demonstrate the performance of both loads that are tested to the single phase Unipolar SPWM inverter under the modulation ratio of 0.8. The performances will be covered in term of the waveform behavior and THDv performance. The project are carried out through the simulation using PSIM software and real implementation to the real hardware. The selection of filter for this paper is the low pass passive LC filter.

Lower Salinity Leads to Improved Physiological Performance in the Coccolithophorid Emiliania huxleyi, Which Partly Ameliorates the Effects of Ocean Acidification

While seawater acidification induced by elevated CO2 is known to impact coccolithophores, the effects in combination with decreased salinity caused by sea ice melting and/or hydrological events have not been documented. Here we show the combined effects of seawater acidification and reduced salinity on growth, photosynthesis and calcification of Emiliania huxleyi grown at 2 CO2 concentrations (low CO2 LC：400 μatm; high CO2 HC：1000 μatm) and 3 levels of salinity (25, 30 and 35‰). A decrease of salinity from 35 to 25‰ increased growth rate, cell size and photosynthetic performance under both LC and HC. Calcification rates were higher in the LC compared to the HC-grown cells only at 25‰ salinity, with insignificant changes under 30 and 35‰ levels. Since salinity and OA treatment did not bring about interactive effects on calcification, changes in calcification are attributed to the elevated dissolved inorganic carbon concentration, with higher ratios of calcification to photosynthesis in the cells grown under 35‰ compared with those grown at 25‰. In contrast, photosynthetic carbon fixation increased almost linearly with decreasing salinity, regardless of the pCO2 treatments. When subjected to short-term exposure to high light, the low-salinity-grown cells showed the highest photochemical effective quantum yield with the highest repair rate, though the HC treatment enhanced the PSII damage rate. Our results suggest that Emiliania huxleyi can tolerate low salinity plus acidification conditions by up-regulating its photosynthetic performance, but shows a relatively insensitive calcification response, which may help it better adapt to future ocean global environmental changes, especially in the coastal areas of high latitudes.

Stationary quantum entanglement between a massive mechanical membrane and a low frequency LC circuit

We study electro-mechanical entanglement in a system where a massive membrane is capacitively coupled to a low frequency LC resonator. In opto- and electro-mechanics, the entanglement between a megahertz (MHz) mechanical resonator and a gigahertz (GHz) microwave LC resonator has been widely and well explored, and recently experimentally demonstrated. Typically, coupling is realized through a radiation pressure-like interaction, and entanglement is generated by adopting an appropriate microwave drive. Through this approach it is however not evident how to create entanglement in the case where both the mechanical and LC oscillators are of low frequency, e.g., around 1 MHz. Here we provide an effective approach to entangling two low-frequency resonators by further coupling the membrane to an optical cavity. The cavity is strongly driven by a red-detuned laser, sequentially cooling the mechanical and electrical modes, which results in stationary electro-mechanical entanglement at experimentally achievable temperatures. The entanglement directly originates from the electro-mechanical coupling itself and due to its quantum nature will allow testing quantum theories at a more macroscopic scale than currently possible.

Collective excitations and field induced anti-ferroelectric modes in chiral liquid crystal dimer

Collective excitations and field influence are investigated in tilted or orthogonal layered liquid crystal smectic (Sm) phases in a chiral hydrogen bonded (HB) calamitic dimer 10OBA:M*SA:10OBA by low-frequency dielectric spectroscopy. Phase transition temperatures, hysteresis, and phase thermal ranges are determined. The hysteresis in SmC* reveals the storage device suitability. The magnitude of the tilt angle in SmC* infers moderate viewing angle. The growth of primary order parameter tilt angle θ(T) infers long range interaction in SmC*. The growth of ferroelectric (FE) relevant secondary order parameter polarization Ps(T) infers strong layer-over-layer helical coupling of transverse dipole moment μt. Dispersion (loss vs permittivity) in 1D SmC*, 3D orthogonal SmBcryst, and 3D hexagonal tilted SmG crystal phases infers two distinct collective modes, viz., high frequency soft mode (SM) and low frequency Goldstone mode (GM). The dielectric strength of the SM in the SmC* phase confirms the FE Curie–Weiss behavior. The GM persists down to low temperature 3D LC phases. The AF order in SmC* is smeared by high temperature thermal fluctuations. A bias field resolves the GM in SmC* to reveal antiferroelectric (AF) modes. AF order manifested as GM1 and GM2 is explained by distinct Ps helices with different relaxation frequencies fR1 and fR2. GM1 and GM2 in 3D SmBcryst and SmG phases are explained by quenching by crystal field. HB LC dimer with a just shifted chiral center promoted the occurrence of field induced AF modes. AF P-switching in SmC* infers the gray scale mode. Trends of dielectric parameters, relaxation frequency, loss maximum, activation energy, dielectric strength, distribution parameter, etc., are discussed with respect to utility in appliances.

High-voltage and high-current crowbar system based on pseudospark switches: from system design to verification

This paper presents a high-voltage and high-current crowbar system using pseudospark switches to produce a fast front edge and prolonged pulse current with low ripple amplitude. The crowbar system mainly consists of a main switch, a crowbar switch, an energy storage capacitor, and an inductive load. The basic parameters of the pseudospark switch crowbar system: the storage capacitance is 5 μF, the typical operation voltage is 30 kV, the peak discharge current is about 46.2 kA, the rise time is 4.3 μs, and the pulse duration time is approximately 109 μs, which is nearly 25 times of the rise time. In this paper, we report the timing setting for crowbar system. Experimental results show that crowbar timing should be set slightly after first current maximum, which has a great advantage of increasing the time scale without any reduction in the loss-free peak current. In addition, the pulse current characteristics are also studied. In the research, crowbar inductance Lc and crowbar resistance Rc have significant effects on the ripple amplitude and load current amplitude of pulse current. The experimental results also show that the crowbar current Ic can reach nearly twice of the coil load current Iload with low crowbar inductance Lc. The over-current capacity of the crowbar switch needs to be greater than that of the main switch. The experimental results in this paper can be used to optimize the inductive load current in high-voltage and high-current crowbar system.

Investigation of the Causal Association between Long-Chain n-6 Polyunsaturated Fatty Acid Synthesis and the Risk of Type 2 Diabetes: A Mendelian Randomization Analysis

Background: Globally, 1 in 11 adults has diabetes mellitus, and most of these cases are type 2 diabetes (T2D). The risk of T2D is influenced by many factors, including diet. The synthesis of long-chain n-6 polyunsaturated fatty acids (LC n-6 PUFA) has been posited as a risk factor for T2D; however, its causal role is uncertain. Aim: To test the causal effect of LC n-6 PUFA synthesis on insulin resistance and transgenerational T2D risk in a large cohort of men and women. Methods: Two-sample mendelian randomization (MR) was conducted to evaluate the effect of low or high levels of LC n-6 PUFA synthesis on glycemia and development of T2D in the UK Biobank (n = 463,010) and Meta-Analysis of Glucose- and Insulin-Related Traits Consortium (MAGIC; n = 5,130) cohorts. The increased likelihood of a predisposition to low or high LC n-6 PUFA synthesis and the risk of T2D was also investigated using the participants’ siblings and parents. In MR-Base, 4 genetic variants associated with LC n-6 PUFA synthesis were found (p < 10^–8). After pruning, 1 variant (rs174547) on the FADS1 gene was retained. Results: Lower LC n-6 PUFA synthesis and abundance (per % unit decrease) are associated with small reductions in the insulin disposition index (–0.038 ± 0.012 mM^–1; p = 0.002) within MAGIC. In the UK Biobank, we report negligible effects of low n-6 PUFA synthesis on the odds of T2D (OR <1%; p < 0.05). Additionally, reduced LC n-6 PUFA synthesis does not appear to be a contributor to familial T2D risk. No significant association was observed between LC n-6 PUFA synthesis and BMI. Conclusion: In a primarily white European population, LC n-6 PUFA synthesis is not a major contributor to T2D risk.

Red complex periodontal pathogens are risk factors for liver cirrhosis.

Periodontal disease has been associated with liver disease; however, the identities of the periodontal disease-causing bacteria in patients with viral liver disease remain unknown. The aim of the present study was to determine the counts of the 3 periodontal pathogens that form the red complex in chronic periodontitis (Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola) and 3 other bacteria (Aggregatibacter actinomycetemcomitans, Prevotella intermedia and Fusobacterium necrophorum) in patients with liver disease. A total of 47 patients with liver disease were divided into two groups based on the counts of the red complex bacteria: group A (high counts of red complex bacteria) and group B (low counts of red complex bacteria). The counts of the 6 types of bacteria in saliva and the prevalence of P. gingivalis-specific fimA genotype were determined. In addition, salivary occult blood tests and serological assays were performed. Univariate and multivariate logistic regression analyses were used to analyze the risk factors between the two groups of patients. Hepatitis C virus-related liver disease was the most frequent (41/47; 87.2%) occurrence followed by liver cirrhosis (LC; 12/47; 25.5%) and oral lichen planus (32/47; 68.1%). The significant risk factors between the two groups were LC, albumin (Alb) level, ratios of each bacteria and prevalence of the fimA II genotype. The 3 factors identified in the multivariate analysis to be associated with the red complex bacteria count were low Alb level (<3.7 g/dl), LC and fimA II genotype, with adjusted odds ratios of 6.93, 4.72 and 4.08, respectively (P<0.05). These data indicated that patients with LC were at increased risk of presenting with the red complex bacteria leading to periodontal disease progression. Therefore, these patients may need to take additional care of their oral health compared with patients without LC, which may prove beneficial for the maintenance of their general health.

Thermal Stability and Kinetic Study on Thermal Degradation of Vitamin D3 in Fortified Canola Oil.

Nowadays, fortified vegetable oils with vitamin D3 are widely available in different countries and are consumed daily. The reduction rate of added vitamin D3 in fortified canola oil during heating process, the changes in oxidative status, and the thermal kinetic degradation of vitamin D3 in the fortified oil were investigated. For this purpose, canola oil was fortified at two levels of vitamin D3 with 5.625 µg/mL (low concentration or LC) and 13.585 µg/mL (a high concentration or HC). Samples were heated isothermally at 100, 150, and 180 °C for 30 min. The vitamin D3 concentration was determined by the high-performance liquid chromatographic method. The retention of vitamin D3 in samples treated at 100 °C for 30 min showed no significant reduction. Samples treated at 150 and 180 °C depending on the initial concentration showed the retention of 67.5% to 72.97% and 33.16% to 40.35% of vitamin D3 , respectively. An inverse relationship was found between the increment of lipid oxidation products (peroxide and anisidine values) and the retention of vitamin D3 . Kinetic parameters such as rate constant, activation energy, decimal reduction time, and quotient indicator were also calculated. An Arrhenius relationship was used for the assessment of temperature dependence of vitamin D3 degradation. Activation energies for vitamin D3 in LC and HC between 100 and 180 °C were found to be 44.01 and 38.77 kJ/mol, respectively. PRACTICAL APPLICATION: The oil can be fortified with vitamin D3 at low cost and offers a good bioavailability. A high-temperature cooking method may not be appropriate for the fortified products containing high lipid content.

Interaction between dietary fatty acids and genotype on immune response in Atlantic salmon (Salmo salar) after vaccination: A transcriptome study.

A pivotal matter to aquaculture is the sourcing of sustainable resources as ingredients to aquafeeds. Levels of plant delivered oils as source of fatty acids (FA) in aquafeeds have reached around 70% resulting in reduced levels of long-chain omega-3 polyunsaturated fatty acids (LC n-3 PUFA), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), in salmon fillet composition. EPA and DHA can modulate inflammation and immune response, so it is crucial to understand how fish immune response is affected by low LC n-3 PUFA diet and if this diet can have a detrimental effect on vaccine response. Atlantic salmon (Salmo salar) can produce EPA/DHA from α-linolenic acid (ALA) and this endogenous capacity can be explored to develop families with higher tolerance to low LC n-3 PUFA diets. Here we analyze innate and adaptive immune response in Atlantic salmon to a commercial vaccine after being fed low levels of EPA and DHA, and we also compare three strains of salmon selected by their endogenous capacity of synthesizing LC- n-3 PUFA. A total of 2,890 differentially expressed genes (DEGs) were identified (p-value adjusted < 0.1) when comparing vaccinated fish against control non-vaccinated. Gene ontology (GO) and KEGG analysis with 442 up/downregulated genes revealed that most DEGs were both related to immune response as well as part of important immune related pathways, as “Toll-like receptor” and “Cytokine-Cytokine interaction”. Adaptive response was also addressed by measuring antigen specific IgM, and titers were significantly higher than in the pre-immune fish at 62 days post-immunization. However, diet and strain had no/little effect on vaccine-specific IgM or innate immune responses. Atlantic salmon therefore display robustness in its response to vaccination even when feed low levels of LC n-3 PUFA.

Effects of early long-chain n-3HUFA programming on growth, antioxidant response and lipid metabolism of Siberian sturgeon (Acipenser baerii Brandt)

The effects of early LC n-3HUFA programming on growth performance, antioxidant response and lipid metabolism on Siberian sturgeon were studied. Two groups of diets with high or low levels of LC n-3HUFA for larvae by microcapsule processing (diet E1 and E2 with 34.6 and 6.5 g/kg) and for grow-up by extrusion (diet J1 and J2 with 34.4 and 7.8 g/kg) were prepared respectively. During the early programming period (8–32 days post-hatching, dph), larval fish were divided into 2 groups, and named group EH (fed diet E1) and EL (fed diet E2), then both groups were fed diet J1 during 33 - 55dph (the intermediate period), then fed diet J2 from 56dph to 77dph (the adaptability period). The results showed that the specific growth rate of group EH was significantly higher than that of group EL during 8-32dph, but the survival rate between the two groups was no difference. During the 33–55dph, although the final body weight of EL group was still lower, a higher complementary SGR was observed in this group. By the end of 77dph, growth performance of the two groups was no difference anymore. Both groups of fish kept antioxidant homeostasis during all feeding stages. The whole-body EPA and DHA levels of the EL group were significantly lower than those of the EH Group at 77dph. At 18dph, a high mortality was observed for both of groups, and simultaneously, except the dull reaction of the gene expression of ELOVL5, which engages for the EPA and DHA synthesis, other tested genes related to fatty acid synthesis, desaturation and elongation (FASN, FADS1/2, ELOVL6) in fish experienced low dietary LC n-3HUFA were positively up-regulated. Fish of EL group also significantly up-regulated the mRNA levels of genes related lipolysis/β-oxidation (PPARα, HL and LPL), which could be related to the higher energy-supply efficient of 18:1n-9 in soy oil. In conclusion, LC n-3HUFA is essential for early ontogenesis of Siberian sturgeon, but it had a minor influence on growth and lipid metabolism in later life, which could be related to the progressively elaborated HUFA synthesis capability in grow-up Siberian sturgeon.

The NAO affects the reproductive potential of small tuna migrating from the Mediterranean Sea

Several studies have confirmed that the North Atlantic Oscillation (NAO) has a direct effect on tuna across a range of biological aspects, such as abundance, catchability, recruitment, and physical condition (LC), especially during winter season (NAOw). However, its effect on reproductive biology has been barely investigated. Thus, the main aim of this study was to investigate the effect of the NAO on the physical condition index and gonadosomatic index (GSI) of the three most commercially exploited small species of migrating tuna (i.e. little tunny, bullet tuna, and Atlantic bonito) in the Mediterranean Sea. A positive direct correlation was found between little tunny and Atlantic bonito and the gonadosomatic and the physical condition indexes. In addition, a strong correlation was found between the NAOw and the gonadosomatic and LC indexes, which could lead to higher reproductive investment in gonad growth before the spawning season. In contrast, bullet tuna had a low LC index during peak gonad growth and were less affected by NAOw oscillations. In the case of bullet tuna, these results could be explained by a longer reproductive period that would lead to faster fat consumption before the reproductive period than in the other species considered and greater dependence on the surrounding environmental conditions for reproductive success.

Toward highly sensitive and reproducible LC-MS/MS analysis of MK-8591 phosphorylated anabolites in human peripheral blood mononuclear cells.

Aim: MK-8591 (EFdA), a novel anti-HIV nucleoside analog, is converted to mono-, di- and tri-phosphates (MK-8591-MP, MK-8591-DP and MK-8591-TP) intracellularly, among which MK-8591-TP is the active pharmacological form. An ultrasensitive LC-MS/MS assay was required to measure MK-8591-DP and MK-8591-TP levels in human peripheral blood mononuclear cells (PBMCs). Sensitivity and reproducibility were major bottlenecks in these analyses. Materials and methods: Human PBMCs were isolated from blood and lysed with 70/30 methanol/RPMI-1640. An LC-MS/MS method was developed to simultaneously quantify MK-8591-DP and MK-8581-TP in PBMC lysates.Results: Low flow LC and dimethyl sulfoxide mediated signal enhancement enabled an extreme sensitivity with limit of quantitation at 0.1ng/ml. Assay accuracy was 92.5-106% and precision was 0.7-12.1% for a linear curve range of 0.1-40ng/ml. Matrix variability and interference liability were comprehensively evaluated. Conclusion: Our study findings and steps taken in addressing clinical sample issues help understand and overcome the challenges facing intracellular nucleotide analog analysis.

Design of High Frequency, Low Phase Noise LC Digitally Controlled Oscillator for 5G Intelligent Transport Systems

This paper presents the design, simulation, and measurements of a low power, low phase noise 10.25–11.78 GHz LC digitally controlled oscillator (LC DCO) with extended true single phase clock (E-TSPC) frequency divider in 130 nm complementary metal–oxide–semiconductor (CMOS) technology for 5G intelligent transport systems. The main goal of this work was to design the LC DCO using a mature and low-cost 130 nm CMOS technology. The designed integrated circuit (IC) consisted of two parts: the LC DCO frequency generation and division circuit and an independent frequency divider testing circuit. The proposed LC DCO consisted of the following main blocks: the high Q-factor inductor, switched-capacitors block, cross-coupled transistors, and the current control block. Inductors with switched-capacitors block formed an LC tank. The designed E-TSPC frequency divider consisted of eight blocks connected in a series; each block increased the division ratio by a factor of two. The frequency of the input signal was divided in the region from two to 256 times using the designed divider. The main parameters of the designed E-TSPC divider and the LC DCO measurements were given as follows: LC DCO achieved a wide tuning range from 10.25 GHz to 11.78 GHz (1.53 GHz, 15.28% bandwidth); phase noise at 1 MHz offset frequency from LC DCO lowest carrier frequency was −113.42 dBc/Hz; phase noise at 1 MHz offset frequency from LC DCO highest carrier frequency was −110.51 dBc/Hz; The average power consumption of the designed LC DCO core and E-TSPC divider were 10.02 mW and 97.52 mW, respectively; the figure of merit (FOM) and the extended FOMT values of the proposed LC DCO were −183.52 dBc/Hz and −187.20 dBc/Hz, respectively. These FOM and FOMT results were achieved due to very low phase noise (−113.52 dBc/Hz) and a wide frequency tuning range (15.28%). The total layout area including the pads was 1.5 mm × 1.5 mm, with the largest part of the layout occupied by the proposed LC DCO (193 µm × 311 µm). The largest part of the LC DCO was occupied by the inductor 184 µm × 184 µm. The manufactured chip was packed into a quad flat no-leads (QFN) 20 pads package.

Stability Design of Single-Loop Voltage Control With Enhanced Dynamic for Voltage-Source Converters With a Low LC-Resonant-Frequency

Voltage-controlled voltage-source converters (VSCs) are widely applied in islanded microgrids, dynamic voltage restorers, and uninterruptible power supplies, etc. Typically, an LC filter with a large filter capacitance is employed to improve the quality of output voltage and system robustness against external disturbances. Nevertheless, a large capacitance may lead to a low LC -resonant-frequency and cause unstable voltage control of VSCs when a single-loop proportional-resonant (PR) or resonant controller is used. This paper proposes a novel design of single-loop voltage control, where a negative proportional gain is adopted in the PR voltage controller, and it is revealed that the voltage control can be stable even with a low LC -resonant-frequency, e.g., lower than one-third of the system sampling frequency. To tackle the poor dynamic issue introduced by the negative proportional gain, this paper further proposes a closed-loop zeros configuration-based control method, which can flexibly tune the system dynamic response without affecting its stability. Finally, simulation and experimental results are provided to verify the effectiveness of the proposed method.

Power Efficient Implementation of Low Noise CMOS LC VCO using 32nm Technology for RF Applications

Voltage Controlled Oscillator (VCO) is an integral component of most of the receivers such as GSM, GPS etc. As name indicates, oscillation is controlled by varying the voltage at the capacitor of LC tank. By varying the voltage, VCO can generate variable frequency of oscillation. Different VCO Parameters are contrasted on the basis of phase noise, tuning range, power consumption and FOM. Out of these phase noise is dependent on quality factor, power consumption, oscillation frequency and current. So, design of LC VCO at low power, low phase noise can be obtained with low bias current at low voltage. Nanosize transistors are also contributes towards low phase noise. This paper demonstrates the design of low phase noise LC VCO with 4.89 GHz tuning range from 7.33-11.22 GHz with center frequency at 7 GHz. The design uses 32nm technology with tuning voltage of 0-1.2 V. A very effective Phase noise of -114 dBc / Hz is obtained with FOM of -181 dBc/Hz. The proposed work has been compared with five peer LC VCO designs working at higher feature sizes and outcome of this performance comparison dictates that the proposed work working at better 32 nm technology outperformed amongst others in terms of achieving low Tuning voltage and moderate FoM, overshadowed by a little expense of power dissipation.

Adaption of a parallel-path poly(tetrafluoroethylene) nebulizer to an evaporative light scattering detector: Optimization and application to studies of poly(dimethylsiloxane) oligomers as a model polymer

The adaption of an parallel-path poly(tetrafluoroethylene)(PTFE) ICP-nebulizer to an evaporative light scattering detector (ELSD) was realized. This was done by substituting the originally installed concentric glass nebulizer of the ELSD. The performance of both nebulizers was compared regarding nebulizer temperature, evaporator temperature, flow rate of nebulizing gas and flow rate of mobile phase of different solvents using caffeine and poly(dimethylsiloxane) (PDMS) as analytes. Both nebulizers showed similar performances but for the parallel-path PTFE nebulizer the performance was considerably better at low LC flow rates and the nebulizer lifetime was substantially increased. In general, for both nebulizers the highest sensitivity was obtained by applying the lowest possible evaporator temperature in combination with the highest possible nebulizer temperature at preferably low gas flow rates. Besides the optimization of detector parameters, response factors for various PDMS oligomers were determined and the dependency of the detector signal on molar mass of the analytes was studied. The significant improvement regarding long-term stability made the modified ELSD much more robust and saved time and money by reducing the maintenance efforts. Thus, especially in polymer HPLC, associated with a complex matrix situation, the PTFE-based parallel-path nebulizer exhibits attractive characteristics for analytical studies of polymers.