24 research outputs found

    A Charge-Sensitive Amplifier Associated with APD or PMT for Positron Emission Tomography Scanners

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    to be presented at the 32nd International Convention MIPRO (Microeectronics, Electronics, and Electronic Technology (MEET)), Opatija, Croatia, May 25-29 2009We present a Charge-Sensitive Amplifier (CSA) to be coupled with a 511-KeV 2-photon detector for positron emission tomography scanners. The circuit has been designed to be associated with an Avalanche Photodiode (APD) or Photo-Multiplier Tube (PMT) with large capacitance. It is a two-stage structure. The input stage consists of a foldedcascode fully-differential part and a common-mode feedback (CMFB) circuit. The output stage employs complementary source followers. The amplifier has been designed in a 0.35μm BiCMOS process with optimization of noise and speed performances to meet specific constraints. Its main characteristics evaluated by post-layout simulations are: 70-dB DC gain, 4.6-GHz GBW, 20-ns peaking time for pulsed stimulus, 3900-electron equivalent input noise charge (ENC), 135-mW power consumption at 3.5 V supply

    NMR planar microcoil for microanalysis

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    This article deals with the analysis of small sample volume by using a planar microcoil and a micromachined cavity. This microcoil is used as a nuclear magnetic resonance (NMR) radio frequency detection coil in order to perform in vitro NMR analysis of the sample introduced into the microcavity. It is a real challenging task to develop microsystem for NMR spectrum extraction for smaller and smaller sample volume. Moreover, it is advantageous that these microsystems could be integrated in a Micro Total Analysing System (μ\mu -TAS) as an analysing tool. In this paper, NMR theory, description, fabrication process and electrical characterization of planar microcoils receiver are described. Results obtained on NMR microspectroscopy experiments have been performed on water and ethanol, using a 1 mm diameter planar coil. This microcoil is tuned and matched at 85.13 MHz which is the Larmor frequency of proton in a 2 T magnetic field

    A time-integration based quenching circuit for Geiger-mode avalanche diodes

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    Sister cytotoxic CD8+ T cell clones differing in natural killer inhibitory receptor expression in human astrocytoma

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    Natural killer (NK) inhibitory receptors are thought to play a critical role in the regulation of cytotoxicity of NK cells and certain self-reactive T cells. In the present study, we investigated whether astrocytoma infiltrating T lymphocytes may be functionally compromised by NK receptors (NKRs). The NK inhibitory receptor CD94/NKG2A was found on a significant proportion of CD8+ astrocytoma infiltrating lymphocytes. The functional consequences of CD94/NKG2A expression were explored at the clonal level, using a T cell clone that exhibited substantial variation in the expression of this heterodimer. Triggering of CD94/NKG2A inhibited the killing properties of T cells with a high level of this receptor, but not those from T cells with a low level. Our data indicate that some astrocytoma infiltrating lymphocytes express functional inhibitory CD94/NKG2A, raising the possibility that they may represent silent T cells specific for self-antigens (Ags) expressed on tumor cells. Understanding the mechanisms of regulation of these receptors may bring new insights for optimizing an anti-tumor immune response

    A CMOS microcoil-associated preamplifier for NMR spectroscopy

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