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

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

A mixed-signal integrated circuit for FM-DCSK modulation

This paper presents a mixed-signal application-specific integrated circuit (ASIC) for a frequency-modulated differential chaos shift keying (FM-DCSK) communication system. The chip is conceived to serve as an experimental platform for the evaluation of the FM-DCSK modulation scheme, and includes several programming features toward this goal. The operation of the ASIC is herein illustrated for a data rate of 500 kb/s and a transmission bandwidth in the range of 17 MHz. Using signals acquired from the test platform, bit error rate (BER) estimations of the overall FM-DCSK communication link have been obtained assuming wireless transmission at the 2.4-GHz ISM band. Under all tested propagation conditions, including multipath effects, the system obtains a BER = 10-3 for Eb/No lower than 28 dB.Ministerio de Ciencia y Tecnología TIC2003-0235

Time-averaged shallow water model: asymptotic derivation and numerical validation

The objective of this paper is to derive, from the Navier-Stokes equations in a shallow domain,a new bidimensional shallow water model able to filter the high frequency oscillations that are produced, when the Reynolds number is increased, in turbulent ows. With this aim, the non- dimensional Navier-Stokes equations are time-averaged, and then asymptotic analysis techniques have been used as in our previous works. The small non-dimensional parameter considered, "e", is the quotient between the typical depth of the basin and the typical horizontal length of the domain; and it is studied what happens when "e" becomes small. Once the new model has been justified, by the method of asymptotic expansions, we perform some numerical experiments. The results of these experiments con rm that this new model is able to approximate analytical solutions of Navier-Stokes equations with more accuracy than classical shallow water models, when high frequency oscillations appear. To reach a given accuracy, the time step for the new model can be much larger (even four hundred times larger) than the time step required for the classical models

Un modelo de aguas someras con dependencia explícita de la profundidad

En este trabajo estudiamos las ecuaciones bidimensionales de Eurler en un dominio con poca profundidad. Con este propósito, se introduce un pequeño parámetro adimensional ε relacionado con la profundidad y se aplica la técnica de los desarrollos asintóticos para estudiar lo que sucede cuando ε se hace pequeño. Se obtiene un modelo para ε pequeño que, tras deshacer el cambio de variable, en el dominio original, proporciona un modelo de aguas someras que incluye los efectos de un fondo no constante y cuya velocidad horizontal depende de z a través de la vorticidad (cuando ´esta no es nula). Esta dependencia hacen que el modelo obtenido sea novedoso respecto a los modelos de aguas someras que pueden encontrarse actualmente en la literatura. Además, este modelo se obtiene sin necesidad de imponer hipótesis a priori sobre la velocidad o la presión. El nuevo modelo es capaz de aproximar las soluciones de las ecuaciones de Euler con dependencia en z (reobteniendo el mismo perfil de velocidades), mientras que el modelo clásico únicamente calcula la velocidad media en la vertical.Ministerio de Educación y Cienci

De Románico y románicos: una aproximación a la doble naturaleza del románico popular

El mundo románico, y más concretamente sus manifestaciones artísticas y culturales, presentan tal riqueza que difícilmente pueden englobarse todas bajo los mismos parámetros de análisis y estudio. Por esta razón este trabajo trata de reflexionar sobre una de esas múltiples manifestaciones, el románico popular, para a partir de su doble naturaleza como obra artística y objeto de la cultura material, tratar de definirlo y adaptar la metodología de su estudio; al tiempo que reivindicarlo como materia de investigación científica y abogar por su necesaria puesta en valor.The Romanesque world, and particularly its artistic and cultural implications, includes such richness that it would be extremely difficult to include all of them under the same criteria of analysis and research. It is for this reason that the present work tries to make a considerations about one of these different expressions, popular Romanesque. From the starting point of its double essence, as an art piece and material culture object, we try to define it and to adapt the method of such study; at the same time we vindicate it as scientific subject and defend its important role

Partiality and its dual in natural implicative expansions of Kleene’s strong 3-valued matrix with only one designated value

26 p.Equivalent overdetermined and underdetermined bivalent Belnap–Dunn type semantics for the logics determined by all natural implicative expansions of Kleene’s strong 3-valued matrix with only one designated value are provided.S

A Sub-µW Reconfigurable Front-End for Invasive Neural Recording

This paper presents a sub-μW ac-coupled reconfigurable front-end for the purpose of neural recording. The proposed topology embeds in it filtering capabilities allowing it to select among different frequency bands inside the neural signal spectrum. Power consumption is optimized by designing for bandwidth-specific noise targets that take into account the spectral characteristics of the input signal as well as the noise bandwidths of the noise generators in the circuit itself. An experimentally verified prototype designed in a 180 nm CMOS process draws a maximum of 815 nW from a 1 V source. The measured input-referred spot-noise at 500 Hz is 75 nV/√Hz while the integrated noise in the 200 Hz - 5 kHz band is 4.1 μVrms.Ministerio de Economía y Competitividad TEC2016-80923- PJunta de Andalucía TIC 233