Novel active-compensated weighted summer

A summer amplifier with extended bandwidth is proposed. Compensation of the frequency characteristics is achieved by employing two operational amplifiers instead of external reactive components

On the Active Compensation of Operational Amplifier Based VCVS

A unified treatment of the active compensation for VCVS realized by operational amplifiers is presented. It is a summary of low-sensitivity circuit structures which can be either magnitude or phase compensated. The performance of such a circuits is discussed in detail. Experimental data for some of them are also included

Validación de la versión española del Cuestionario Breve de Evitación Experiencial (BEAQ) en población clínica

The Brief Experiential Avoidance Questionnaire (BEAQ) has been suggested as the most appropriate instrument for measuring experiential avoidance. However, no Spanish validation has been published. The aim of this study was to validate a Spanish version of the BEAQ in a clinical sample treated at a community mental health unit. Methods: Participants (N = 332) completed the BEAQ as well as other self-report measures of experiential avoidance and psychopathology. Results: Internal consistency was satisfactory (α = .82). No statistically significant gender differences were found in the BEAQ scores. The data also showed high test-retest reliability after four to six weeks, acceptable concurrent validity with another experiential avoidance measure and acceptable convergent validity with the psychopathology measure. The principal component analysis, forcing the one factor solution proposed in the original scale, produced indicators similar to the English version of the BEAQ. Conclusions: These results firmly support the reliability and validity of this Spanish validation, stressing its usefulness as a measure of experiential avoidance in clinical populations.Antecedentes: el Cuestionario Breve de Evitación Experiencial (BEAQ) ha sido propuesto como el instrumento más adecuado para medir la evitación experiencial. Sin embargo, todavía no ha sido publicada ninguna validación en español. Por lo tanto, el objetivo del presente estudio ha sido la validación de una versión española del BEAQ, en una muestra clínica atendida en un Centro de Salud Mental Comunitario. Método: los participantes (N = 332) completaron el BEAQ, así como otras medidas de autoinforme de evitación experiencial y psicopatología. Resultados: la consistencia interna fue satisfactoria (α = .82). No se encontraron diferencias de género estadísticamente significativas en las puntuaciones del BEAQ. Los datos también mostraron una alta fiabilidad test-retest en un intervalo de cuatro a seis semanas, validez concurrente aceptable con otra medida de evitación experiencial y validez convergente aceptable con la medida de psicopatología. El análisis de componentes principales forzando a la solución de un factor, como se propuso en la escala original, obtuvo unos indicadores similares a los obtenidos en dicha versión inglesa. Conclusiones: los resultados confirman la adecuada fiabilidad y validez de la presente versión española del BEAQ, destacando su utilidad como medida de la evitación experiencial en población clínica

A 64-channel inductively-powered neural recording sensor array

This paper reports a 64-channel inductively powered neural recording sensor array. Neural signals are acquired, filtered, digitized and compressed in the channels. Additionally, each channel implements a local auto-calibration mechanism which configures the transfer characteristics of the recording site. The system has two operation modes; in one case the information captured by the channels is sent as uncompressed raw data; in the other, feature vectors extracted from the detected neural spikes are transmitted. Data streams coming from the channels are serialized by an embedded digital processor and transferred to the outside by means of the same inductive link used for powering the system. Simulation results show that the power consumption of the complete system is 377μW.Ministerio de Ciencia e Innovación TEC2009-0844

A power efficient neural spike recording channel with data bandwidth reduction

This paper presents a mixed-signal neural spike recording channel which features, as an added value, a simple and low-power data compression mechanism. The channel uses a band-limited differential low noise amplifier and a binary search data converter, together with other digital and analog blocks for control, programming and spike characterization. The channel offers a self-calibration operation mode and it can be configured both for signal tracking (to raw digitize the acquired neural waveform) and feature extraction (to build a first-order PWL approximation of the spikes). The prototype has been fabricated in a standard CMOS 0.13μm and occupies 400μm×400μm. The overall power consumption of the channel during signal tracking is 2.8μW and increases to 3.0μW average when the feature extraction operation mode is programmed.Ministerio de Ciencia e Innovación TEC2009-08447Junta de Andalucía TIC-0281

l-Amino Acid Production by a Immobilized Double-Racemase Hydantoinase Process: Improvement and Comparison with a Free Protein System

Protein immobilization is proving to be an environmentally friendly strategy for manufacturing biochemicals at high yields and low production costs. This work describes the optimization of the so-called “double-racemase hydantoinase process,” a system of four enzymes used to produce optically pure l-amino acids from a racemic mixture of hydantoins. The four proteins were immobilized separately, and, based on their specific activity, the optimal whole relation was determined. The first enzyme, d,l-hydantoinase, preferably hydrolyzes d-hydantoins from d,l-hydantoins to N-carbamoyl-d-amino acids. The remaining l-hydantoins are racemized by the second enzyme, hydantoin racemase, and continue supplying substrate d-hydantoins to the first enzyme. N-carbamoyl-d-amino acid is racemized in turn to N-carbamoyl-l-amino acid by the third enzyme, carbamoyl racemase. Finally, the N-carbamoyl-l-amino acid is transformed to l-amino acid by the fourth enzyme, l-carbamoylase. Therefore, the product of one enzyme is the substrate of another. Perfect coordination of the four activities is necessary to avoid the accumulation of reaction intermediates and to achieve an adequate rate for commercial purposes. The system has shown a broad pH optimum of 7–9, with a maximum activity at 8 and an optimal temperature of 60 °C. Comparison of the immobilized system with the free protein system showed that the reaction velocity increased for the production of norvaline, norleucine, ABA, and homophenylalanine, while it decreased for l-valine and remained unchanged for l-methionine

A 4-mode reconfigurable low noise amplifier for implantable neural recording channels

In this paper a reconfigurable implantable low noise amplifier for the recording of neural signals is presented. It is comprised by low-power and noise efficient current reuse OTAs in its direct path. The proposed architecture allows for an active feedback to set the high-pass corner in place of the commonly used pseudoresistor. Bandwidth selectivity is achieved by circuit reconfigurability which changes the pole frequencies of the system without impacting the total power consumption. Simulation results in AMS 0.18μm technology validate the proposed architecture in both nominal and corner process conditions with an estimated total power consumption of 454nW.Office of Naval Research (USA) N00014-14-1-0355Junta de Andalucía TIC 233

A 2.2 μW analog front-end for multichannel neural recording

In this paper an analog front-end for the multi-channel implantable recording of neural signals is presented. It is comprised by a two-stage AC-coupled low-noise amplifier (LNA) and a one stage AC-coupled variable gain amplifier (VGA). The proposed architecture employs highly power-noise efficient current reuse fully differential OTAs in the LNA stage and a fully differential folded cascode for the VGA stage. Simulation results in AMS 0.18μm validate the proposed architecture under process corners variations with an estimated power consumption of 2.2μm and 3.1 μVrms in-band noise.Ministerio de Economía y Competitividad TEC2016- 80923-POffice of Naval Research (USA) N00014111031