Various 16-bit multiplier architectures are compared in terms of dissipated energy, propagation delay, energy-delay product (EDP), and area occupation, in view of low-power low-voltage signal ...processing for low-frequency applications. A novel practical approach has been set up to investigate and graphically represent the mechanisms of glitch generation and propagation. It is found that spurious activity is a major cause of energy dissipation in multipliers. Measurements point out that, because of its shorter full-adder chains, the Wallace multiplier dissipates less energy than other traditional array multipliers (8.2 mu W/MHz versus 9.6 mu W/MHz for 0.18mum CMOS technology at 0.75 V). The benefits of transistor sizing are also evaluated (Wallace including minimum-size transistors dissipates 6.2 muW/MHz). By combining transmission gates with static CMOS in a Wallace architecture, a new approach is proposed to improve the energy-efficiency further (4.7 muW/MHz), beyond recently published low-power architectures. The innovation consists in suppressing glitches via resistance-capacitance low-pass filtering, while preserving unaltered driving capabilities. The reduced number of V dd -to-ground paths also contributes to a significant decrease of static consumption.
The Virgo interferometer for gravitational wave detection has concluded four months of scientific data acquisition in its final optical configuration (a power-recycled interferometer with Fabry-Perot ...cavities in the arms). The lock acquisition technique developed to bring and keep the Virgo detector on its working point largely proved to be very efficient and robust. In this paper we describe the variable finesse lock acquisition technique and we discuss the performance of the whole locking system.
Following a successful period of data-taking between 2006 and 2011, the Virgo gravitational-wave detector was taken offline for a major upgrade. The changes made to the instrument significantly ...increased the complexity of the control systems and meant that an extended period of commissioning was required to reach a sensitivity appropriate for science data-taking. This commissioning period was completed in July of 2017 and the second-generation Advanced Virgo detector went on to join the Advanced LIGO detectors in the O2 science run in August of the same year. The upgraded detector was approximately twice as sensitive to binary neutron star mergers as the first-generation instrument. During the August 2017 science run, Advanced Virgo detected its first gravitational wave signal, with the binary black hole merger, GW170729. This paper describes the control of the longitudinal degrees of freedom in the Advanced Virgo instrument during the O2 science run and the process that brought the detector from an uncontrolled, non-resonant state to its target working point.
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