Switched-compensation technique in switched-capacitor circuits for achieving fast settling performance

Resolving stability issue is one of the major challenges in designing a perfect op-amp, the most widely used analog circuit block. Many compensation techniques have been proposed to improve the stability performance of op amps, but virtually all these techniques were developed for continuous-time applications and subsequently applied to discrete-time applications (e.g., switched-capacitor circuits). Since the early 1980s, an increasing number of op-amps have been used in switched-capacitor circuits with no special compensation method applied. Consequently, there remains a need to explore the possibility of designing a unique compensation method specifically for switched-capacitor use. A new switched-compensation technique (SCT) is proposed for switched-capacitor circuit applications in which high speed is a critical index of performance. In general, designers must deal with trade-offs among accuracy, speed, and power dissipation. SCT avoids traditional approaches of designing high-speed, high-gain operational amplifiers that are in many cases technology-limited. Instead, it modifies the switched-capacitor circuit structure to use the under-damped response of the system, usually regarded as a drawback. SCT is introduced as a novel solution for achieving fast settling performance and lower quiescent power dissipation while guaranteeing almost equivalent accuracy. SCT can be easily implemented in flip-around switched-capacitor amplifier circuits. This paper explains SCT principle and implementation applied to multiplying-digital-to-analog converters (MDACs) as a proof of concept. Simulation results based on an IBM 0.13um CMOS process are presented. Compared with a conventional switched-capacitor amplifier, a SCT-based implementation reduces the quiescent power consumption by half and settling time within 1% error by 60%

Three-Body Recombination near a Narrow Feshbach Resonance in 6 Li

We experimentally measure and theoretically analyze the three-atom recombination rate, L3, around a narrow s-wave magnetic Feshbach resonance of 6Li−6Li at 543.3 G. By examining both the magnetic field dependence and, especially, the temperature dependence of L3 over a wide range of temperatures from a few μK to above 200 μK, we show that three-atom recombination through a narrow resonance follows a universal behavior determined by the long-range van der Waals potential and can be described by a set of rate equations in which three-body recombination proceeds via successive pairwise interactions. We expect the underlying physical picture to be applicable not only to narrow s wave resonances, but also to resonances in nonzero partial waves, and not only at ultracold temperatures, but also at much higher temperatures

Image Restoration using Total Variation Regularized Deep Image Prior

In the past decade, sparsity-driven regularization has led to significant improvements in image reconstruction. Traditional regularizers, such as total variation (TV), rely on analytical models of sparsity. However, increasingly the field is moving towards trainable models, inspired from deep learning. Deep image prior (DIP) is a recent regularization framework that uses a convolutional neural network (CNN) architecture without data-driven training. This paper extends the DIP framework by combining it with the traditional TV regularization. We show that the inclusion of TV leads to considerable performance gains when tested on several traditional restoration tasks such as image denoising and deblurring

SURROGACY, SOCIAL POLICY AND ECONOMIC DEVELOPMENT

Surrogacy policy is a highly complex global policy that has important ramifications, yet it is unclear how a country’s socio-economic status can influence its surrogacy policy. This study quantitatively assessed the influence of economic development on surrogacy policy in 84 countries. Using an internet analytic search and comprehensive literature review, countries were identified for study. Each country’s surrogacy policy and economic development were characterized and an analysis of the relationship between economic development and surrogacy policy was conducted. The analysis demonstrated that economic development acts as a negative predictor for more liberal surrogacy policy, despite its positive impact on other social policies such as abortion and same-sex marriage. This disparity highlights the need for governments to more holistically examine their existing surrogacy policies and ensure greater internal alignment with their other social policies

Parametric cooling of a degenerate Fermi gas in an optical trap

We demonstrate a novel technique for cooling a degenerate Fermi gas in a crossed-beam optical dipole trap, where high-energy atoms can be selectively removed from the trap by modulating the stiffness of the trapping potential with anharmonic trapping frequencies. We measure the dependence of the cooling effect on the frequency and amplitude of the parametric modulations. It is found that the large anharmonicity along the axial trapping potential allows to generate a degenerate Fermi gas with anisotropic energy distribution, in which the cloud energy in the axial direction can be reduced to the ground state value