Design of a 2.4 Ghz BAW-Based CMOS Transmitter

In recent years, bulk acoustic wave resonators (BAW) in combination with RF circuits have shown a big potential in achieving the low-power consumption and miniaturization level required to address wireless sensor nodes (WSN) applications. A lot of work has been focused on the receiver side, by integrating BAW resonators with low noise amplifiers (LNA) and in frequency synthesis with the design of BAW-based local oscillators, most of them working at fixed frequency due to their limited tuning range. At the architectural level, this has forced the implementation of several single channel transceivers. This thesis aims at exploring the use of BAW resonators in the transmitter, proposing an architecture capable of taking full advantage of them. The main objective is to develop a transmitter for WSN multi-channel applications able to cover the whole 2.4 GHz ISM band and enable the compatibility with wide-spread standards like Bluetooth and Bluetooth Low Energy. Typical transmissions should thus range from low data rates (typically tens of kb/s) to medium data rates (1 Mb/s), with FSK and GFSK modulation schemes, should be centered on any of the channels provided by these standards and cover a maximum transmission range of some tens of meters. To achieve these targets and circumvent the limited tuning range of the BAW oscillator, an up-conversion transmitter using wide IF is used. The typical spurs problems related to this transmitter architecture are addressed by using a combined suppression based on SSB mixing and selective amplification. The latter is achieved by cointegration of a high efficiency power amplifier with BAW resonators, which allows performing spurs filtering while preserving the efficiency. In particular the selective amplifier is designed by including in the PA analysis the BAW resonator parameters, which allows integrating the BAW filter into the passive network loading the amplifier, participating in the drain voltage shaping. Finally, the frequency synthesis section uses a fractional division plus LC PLL filtering and further integer division to generate the IF signals and exploit the very-low BAW oscillator phase noise. The transmitter has been integrated in a 0.18 µm standard digital CMOS technology. It allows addressing the whole 80 MHz wide 2.4 GHz ISM band. The unmodulated RF frequency carrier demonstrates a very-low phase noise of –136 dBc/Hz at 1 MHz offset. The IF spurs are maintained lower than –48 dBc, satisfying the international regulations for output power up to 10 dBm without the use of any quadrature error compensation in the transmitter. This is achieved thanks to the rejection provided by the SSB mixer and the selective amplifier, which can reach drain efficiency of up to 24% with integrated inductances, including the insertion losses of the BAW filter. The transmitter consumes 35.3 mA at the maximum power of 5.4 dBm under 1.6 V (1.2 V for the PA), while transmitting a 1 Mb/s GFSK signal and complying with both Bluetooth and Bluetooth Low Energy relative and absolute spectrum requirements

A VHDL-AMS Modeling Methodology for Top-Down/Bottom-Up Design of RF Systems

Indo-ChinaAn agreement between Ho Chi Minh and the French (1946) made Vietnam a free state though fighting between parties erupted into the First Indochina War ending in May 1954.Vietnam. (2013). In Encyclopædia Britannica. Retrieved from http://school.eb.com/eb/article-52744GrayscaleForman Safety Negatives, Box

First‐principles Assessment of the Role of Water in the Reduction Half Cycle of Low‐Temperature NH3‐SCR over Cu‐CHA

Dispersion corrected density functional theory calculations show that the presence of H2O in the Reduction Half-Cycle (RHC) of NH3-SCR affects the free energy of the kinetically-relevant transition state (TS) leading to a reduction in the rate and activation energy with respect to dry conditions. In particular, H2O enthalpically stabilizes the kinetically-relevant TS by 20 kJ mol(-1) with respect to the dry counterpart. Such enthalpic stabilization vanishes when van der Waals (vdW) interactions are excluded from the calculations, thus showing the preeminent role of non-specific dispersion forces in the reduction of the activation enthalpy. At the same time, the enthalpic stabilization is more than compensated by the additional entropy losses of the TS brought forth by the presence of H2O in the CHA cage. Calculated enthalpy and entropy changes with respect to the dry case agree quantitatively with the experimental measurements and reflect the modified reacting environment in the presence of H2O. As a result, this study provides theoretical underpinnings on the mechanistic role of H2O in the RHC and, on a more general basis, highlights the importance of the molecular scale description of the reaction environment in voids of molecular dimensions

A VHDL-AMS Modeling Methodology for Top-Down/Bottom-Up Design of RF Systems

This paper presents a modelling methodology for the top-down/bottom-up design of RF systems based on systematic use of VHDL-AMS models. The model interfaces are parameterizable and pin-accurate. The designer can choose to parameterize the models using performance specifications or device parameters back-annotated from the transistor-level implementation. The abstraction level used for the description of the respective analog/digital component behavior has been chosen to achieve a good trade-off between accuracy, fidelity, and simulation performance. These properties make the models suitable for different design tasks such as architectural exploration or overall system validation. This is demonstrated on a model of a binary FSK transmitter parameterized to meet very different target specifications. The achieved flexibility and systematic model documentation facilitate their reuse in other design projects

Enhanced serum concentrations of transforming growth factor-beta1 in simple fatty liver: is it really benign?

<p>Abstract</p> <p>Background</p> <p>Inside the spectrum of non-alcoholic fatty liver disease, simple fatty liver is generally thought of as being "non progressive", differently from non-alcoholic steatohepatitis, which increases in severity due to the presence of apoptosis/inflammation and fibrosis. The "benignity" of fatty liver is widely accepted but conceptually difficult to maintain because the mechanisms underlying this entity are the same ones that determine the more severe form.</p> <p>Findings provide evidence that iron overload is associated with increased liver damage and collagen deposition. Transforming growth factor-beta1 released by hepatic stellate cells during chronic liver injury plays a critical role in liver apoptosis and fibrogenesis.</p> <p>Objective</p> <p>To verify whether both the forms of non-alcoholic fatty liver disease were really dissimilar, evaluating the serum profile of two key parameters, indexes of severity.</p> <p>Methods</p> <p>A total of 123 patients (57 females) participated, forming three groups: forty five patients with fatty liver, 42 patients with non-alcoholic steatohepatitis and 36 with chronic hepatitis C. All had a biopsy-proven diagnosis.</p> <p>Measurements</p> <p>Serum concentrations of transforming growth factor-beta1 and ferritin.</p> <p>Results</p> <p>High concentrations of transforming growth factor-beta1 were noticed in patients suffering from both fatty liver and non-alcoholic steatohepatitis, 129.1 (45.4) versus 116.8 (42.2) ng/mL, P = 0.2; they were significantly superior to those of chronic hepatitis C patients 87.5 (39.5) ng/mL, P < 0.001. Ferritin levels were on average above normal values and similar in the three groups (P = 0.9), also when adjusted for gender (P = 0.5) and age (P = 0.3).</p> <p>Conclusion</p> <p>No difference between serum concentrations of transforming growth factor-beta1 and ferritin in fatty liver and non-alcoholic steatohepatitis suggests that these forms share more common aspects, regarding their progression, than previously thought.</p

Sleep-potentiated epileptiform activity in early thalamic injuries: Study in a large series (60 cases)

OBJECTIVE: The study aims at a better definition of continuous spike-waves during sleep (CSWS) with an early thalamic lesion, focusing on various grades of sleep-potentiated epileptiform activity (SPEA). Their possible relationship with different clinical features was studied to try to define prognostic factors of the epileptic disorder, especially relating to behavior/cognitive outcome, in order to improve prevention and treatment strategies. METHODS: Sixty patients with early thalamic injury were followed since the first registration of SPEA with serial neurological, long term EEG monitoring and neuropsychological examinations, as well as neuroimaging and a detailed clinical history. They were classified in three different groups according to the sleep spike-waves (SW) quantification: electrical status epilepticus during sleep (ESES), more than 85% of slow sleep; overactivation between 50% and 85% and simple activation between 10 and 50%). Results were then examined also with a statistical analysis. RESULTS: In our series of CSWS occurring in early brain injured children with unilateral thalamic involvement there is a common neuropathologic origin but with various grades of SPEA severity. Statistical analysis showed that patients evolving toward ESES presented more commonly the involvement of the mediodorsal part of thalamus nuclei and a bilateral cortico-subcortical brain injury, epilepsy was more severe with a delayed onset; moreover, in the acute stage .ESES patients presented the worst behavior/cognitive performances. As to cognitive and behavior outcome, longer SPEA duration as well as bilateral brain injury and cognitive/behavior impairment in acute phase appear linked to a poor outcome; some particular neuropathology (ischemic stroke and haemorrhagic infarction) as well as hydrocephalus shunting are associated with behavior disorders. CONCLUSIONS: Discrete features seem to support different underlying mechanisms in ESES patients in comparison with less severe SPEA; they represent negative prognostic factors. Longer SPEA duration as well as bilateral brain injury and cognitive/behavior impairment in acute phase seem predictive of a worse cognitive/behavior outcome