Relativistic global and local divergences in hydrogenic systems: A study in position and momentum spaces

Relativistic effects in one-particle densities of hydrogenic systems are quantified by means of global and local density functionals: the Jensen-Shannon and the Jensen-Fisher divergences, respectively. The Schrödinger and Dirac radial densities are compared, providing complementary results in position and momentum spaces. While the electron cloud gets compressed towards the origin in the Dirac case, the momentum density spreads out over its domain, and the raising of minima in position space does not occur in the momentum space. Regarding the dependence on the nuclear charge and the state quantum numbers for all divergences here considered, as well as their mutual interconnection, accurate powerlike laws y˜Cxa are found systematically. The parameters {C,a} defining the respective dependences are extremely sensitive to the closeness of the system to the ground and/or the circular state. Particularly interesting are the analyses of (i) the plane subtended by the Jensen-Shannon and Jensen-Fisher divergences, in a given space (position or momentum), and (ii) either of the above two divergences in the position-momentum plane. These kinds of results show the complementary role of global and local divergences and that of both conjugate spaces

Super class AB RFC OTA with adaptive local common-mode feedback

A super class AB recycling folded cascode operational transconductance amplifier is presented. It employs local common-mode feedback using two matched tuneable active resistors, allowing to adapt the amplifier to different process variations and loads. Measurement results from a test chip prototype fabricated in a 0.5 μm CMOS process validate the proposal

CMOS First-Order All-Pass Filter With 2-Hz Pole Frequency

A CMOS fully integrated all-pass filter with an extremely low pole frequency of 2 Hz is introduced in this paper. It has 0.08-dB passband ripple and 0.029-mm 2 Si area. It has 0.38-mW power consumption in strong inversion with ±0.6-V power supplies. In subthreshold, it has 0.64-μW quiescent power and operates with ±200-mV dc supplies. Miller multiplication is used to obtain a large equivalent capacitor without excessive Si area. By varying the gain of the Miller amplifier, the pole frequency can be varied from 2 to 48 Hz. Experimental and simulation results of a test chip prototype in 130-nm CMOS technology validate the proposed circuit

Dynamics of a structured slug population model in the absence of seasonal variation

We develop a novel, nonlinear structured population model for the slug Deroceras reticulatum, a highly significant agricultural pest of great economic impact, in both organic and non-organic settings. In the absence of seasonal variations, we numerically explore the effect of life history traits that are dependent on an individual's size and measures of population biomass. We conduct a systematic exploration of parameter space and highlight the main mechanisms and implications of model design. A major conclusion of this work is that strong size dependent predation significantly adjusts the competitive balance, leading to non-monotonic steady state solutions and slowly decaying transients consisting of distinct generational cycles. Furthermore, we demonstrate how a simple ratio of adult to juvenile biomass can act as a useful diagnostic to distinguish between predated and non-predated environments, and may be useful in agricultural settings

Configuration Complexities of Hydrogenic Atoms

The Fisher-Shannon and Cramer-Rao information measures, and the LMC-like or shape complexity (i.e., the disequilibrium times the Shannon entropic power) of hydrogenic stationary states are investigated in both position and momentum spaces. First, it is shown that not only the Fisher information and the variance (then, the Cramer-Rao measure) but also the disequilibrium associated to the quantum-mechanical probability density can be explicitly expressed in terms of the three quantum numbers (n, l, m) of the corresponding state. Second, the three composite measures mentioned above are analytically, numerically and physically discussed for both ground and excited states. It is observed, in particular, that these configuration complexities do not depend on the nuclear charge Z. Moreover, the Fisher-Shannon measure is shown to quadratically depend on the principal quantum number n. Finally, sharp upper bounds to the Fisher-Shannon measure and the shape complexity of a general hydrogenic orbital are given in terms of the quantum numbers.Comment: 22 pages, 7 figures, accepted i

An Op-Amp Approach for Bandpass VGAs With Constant Bandwidth

Two approaches to implement variable gain amplifiers based on Miller op-amps are discussed. One has true constant bandwidth while the other has essentially reduced bandwidth variations with varying gain. Servo-loops and ac coupling techniques with quasi floating gate transistors are used to provide a bandpass response with very low cutoff frequency in the range of hertz. In practice, one of the schemes is shown to have bandwidth variations close to a factor two while the second one has true constant bandwidth over the gain tuning range. Experimental results of test chip prototypes in 180-nm CMOS technology verify the theoretical claims

±0.25-V Class-AB CMOS Capacitance Multiplier and Precision Rectifiers

Reduction of minimum supply requirements is a crucial aspect to decrease the power consumption in VLSI systems. A high-performance capacitance multiplier able to operate with supplies as low as ±0.25 V is presented. It is based on adaptively biased class-AB current mirrors which provide high current efficiency. Measurement results of a factor 11 capacitance multiplier fabricated in 180-nm CMOS technology verify theoretical claims. Moreover, low-voltage precision rectifiers based on the same class-AB current mirrors are designed and fabricated in the same CMOS process. They generate output currents over 100 times larger than the quiescent current. Both proposed circuits have 300-nW static power dissipation when operating with ±0.25-V supplies

±0.3V Bulk-Driven Fully Differential Buffer with High Figures of Merit

A high performance bulk-driven rail-to-rail fully differential buffer operating from ±0.3V supplies in 180 nm CMOS technology is reported. It has a differential–difference input stage and common mode feedback circuits implemented with no-tail, high CMRR bulk-driven pseudo-differential cells. It operates in subthreshold, has infinite input impedance, low output impedance (1.4 kΩ), 86.77 dB DC open-loop gain, 172.91 kHz bandwidth and 0.684 μW static power dissipation with a 50-pF load capacitance. The buffer has power efficient class AB operation, a small signal figure of merit FOMSS = 12.69 MHzpFμW−1, a large signal figure of merit FOMLS = 34.89 (V/μs) pFμW−1, CMRR = 102 dB, PSRR+ = 109 dB, PSRR− = 100 dB, 1.1 μV/√Hz input noise spectral density, 0.3 mVrms input noise and 3.5 mV input DC offset voltage.Junta de Andalucía - Consejería de Economía, Conocimiento, Empresas y Universidades P18-FR-4317Agencia Estatal de Investigación - FEDER PID2019-107258RB-C3

Low-Voltage 0.81mW, 1-32 CMOS VGA with 5% Bandwidth variations and 38dB DC rejection

A CMOS low-voltage amplifier with approximately constant bandwidth and DC rejection is introduced. The design is based on the cascade of a wide linear input range OTA, an op-amp and a servo-loop with extremely large time constants. It operates with ±0.45V supplies and a power consumption of 0.81mW in 180nm technology. The bandwidth changes only from 9.08MHz to 9.54MHz over a gain range from 1 to 32, it has a 9.8Hz low cutoff frequency and a DC attenuation of 38dBs. DC floating voltage sources are used to keep the gates of all differential pairs at a constant value close to a supply rail in order to operate the amplifier circuit with minimum supply voltage. The proposed circuit has small and large signal figures of merit FOM SS = 5380 (MHz*pF/mW) and FOM LS = 0.0085((V/ns)*pF/mA) for a nominal gain A = 32