Abstract-This paper presents the design and implementation of a wideband power amplifier for UWB applications, covering the lower band frequencies of 3.1 GHz to 4.8 GHz. To achieve sufficient linearity and efficiency, this PA operates in the Class-AB regime, delivering an output power of -4.2 dBm at an input-1dB compression point of -22 dBm for a 4 GHz signal. This PA has a differential input and a single-ended output that has been matched to 50Ω at both the ends. Complete design and implementation was done using TSMC 0.18µm CMOS technology and it consumes a very low power of 25 mW, while realizing a flat gain of 19±1 dB across the whole band of operation.

Abstract-The quality factor (Q) of a solidly mounted bulk acoustic wave resonator (SMR) is limited by substrate losses, because the acoustic mirror is traditionally optimized to reflect longitudinal waves only. We propose two different design approaches derived from optics to tailor the acoustic mirror for effective reflection of both longitudinal and shear waves. The first one employs the stopband theory in optics; the second one takes advantage of the periodic nature of reflection spectra in a Bragg reflector: the diffraction grating design approach. The optimized design using stopband theory reaches a calculated minimum transmission of −25 dB and −20 dB at resonance frequency for longitudinal and shear waves, respectively, for various practical reflector material combinations. Using the diffraction grating approach, a near quarter-wave performance is maintained for longitudinal waves, whereas shear waves reach minimum transmission below −26 dB. However, this design does necessitate relatively thick layers. The experimental results show good agreement with finite element models (FEM). The extracted 1-D Q for the realized shear optimized devices was increased to around 3300.I. Introduction b ulk-acoustic-wave (baW) devices are receiving great interest for rF selectivity in mobile communication systems and other wireless applications. Thinfilm baW devices have several advantages compared with saW resonators because they are remarkably small in size, and have better power handling abilities and better temperature coefficients, leading to more stable operation [1]. From a practical point of view, saW filters have considerable drawbacks at frequencies beyond 2 GHz, whereas baW devices up to 20 GHz have been demonstrated [2]. baW is expected to supersede saW as the technology of choice in many applications over the next few years as they have now evolved in performance beyond saW and can be manufactured in a very cost-competitive way using standard Ic technology. baW technology is commercially available for applications using the U.s. Personal communication service (UsPcs) (1.85 to 1.91 GHz) standard. Transmit and receive bands of the Us-Pcs standard are close in frequency [3]. This demands that the baW resonators which constitute the narrow band filters must be nearly loss-free. Hence, one of the important goals of baW community is to come up with high-Q resonators for rF filters by minimizing the losses [4]- [8].The quality factor (Q) of traditional solidly mounted bulk acoustic wave resonators (smrs) is traditionally limited by substrate losses [9]- [13], because the conventional quarter-wave acoustic mirror employed in smrs reflects only the longitudinal acoustic waves and not the shear waves. To obtain high-Q smrs, the mirror should effectively reflect both of the waves. Therefore, the influence of shear waves on Q was reviewed earlier [11]. some optimized stacks have been reported for specific material combinations [9], [10] based on numerical calculations.recently [12], we reported a systematic design procedu...

Background: With Caesarean sections on the rise WHO proposes that health care facilities use the Robson's 10 group classification system to audit their C-sections rates. This classification would help understand the internal structure of the CS rates at individual health facilities identify key population groups, indications in each group and formulate strategies to reduce these rates.Methods: This was a cross sectional study for a period of 24 months at a tertiary care hospital in a tribal area of Kerala South India. Women who delivered during this period were included and classified into 10 Robson's classes and percentages were calculated for the overall rate, the representation of groups, contribution of groups and Caesarean percentage in each group.Results: Highest contribution was by Group 5 and Group 2. Together these two groups contributed to 38% of the total Caesareans. Followed by Group 8 and 10. All four added contributed to 63% of the section rate The least contribution was by Group 3. Groups 6, 7 and 9 by themselves did not contribute much but within their groups had a 100% C-Section rate.Conclusions: The contribution of the various Robson's Group to the absolute C-Section rates needs to be looked into. Reducing primary section rates, adequate counselling and encouraging for VBAC, changing the norms for dystocia and non-reassuring fetal status, training and encouraging obstetricians to perform versions when not contraindicated could reduce the contribution of Robson's groups towards the absolute C-Section rates.

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Modeling has become a vital tool of investigation in all fields, since experimenting with real systems is not only costly, but also time-consuming and even impossible in some situations. This work presents the design and simulation of an integrated PVDF-based MEMS hydrophone with improved sensitivity, which contains a MOSFET sense amplifier. The piezoelectric polymer, polyvinylidene fluoride (PVDF), senses the input acoustic signal. As hydrophone size decreases, it becomes necessary to provide an amplifier or buffer in close proximity to avoid sensitivity loss due to interconnect capacitance. This suggests the concept of hydrophones merged with electronics in an integrated circuit environment. So, the integration of PVDF with an on-chip MOSFET is implemented. The extended gate electrode of the MOSFET is placed over an epitaxial layer isolated from the silicon substrate and is padded with a dielectric layer, SU-8, which significantly reduces the extended gate capacitance and, therefore, increases the sensor sensitivity. The variation of the transducer output when the input acoustic signal is applied is studied. The simulation is done using the MEMS simulation software, Coventorware.