I have developed "tennis elbow" from lugging this book around the past four weeks, but it is worth the pain, the effort, and the aspirin. It is also worth the (relatively speaking) bargain price. Including appendixes, this book contains 894 pages of text. The entire panorama of the neural sciences is surveyed and examined, and it is comprehensive in its scope, from genomes to social behaviors. The editors explicitly state that the book is designed as "an introductory text for students of biology, behavior, and medicine," but it is hard to imagine any audience, interested in any fragment of neuroscience at any level of sophistication, that would not enjoy this book. The editors have done a masterful job of weaving together the biologic, the behavioral, and the clinical sciences into a single tapestry in which everyone from the molecular biologist to the practicing psychiatrist can find and appreciate his or

Principles of Neural Science

http://eia.udg.es/%7Eqsalvi/papers/2006-MJ.pdf

Review of CMOS image sensors

A novel analytical model of inductively coupled wireless power transfer is presented. For the first time, the effects of coil misalignment and geometry are addressed in a single mathematical expression. In the applications envisaged, such as radio frequency identification (RFID) and biomedical implants, the receiving coil is normally significantly smaller than the transmitting coil. Formulas are derived for the magnetic field at the receiving coil when it is laterally and angularly misaligned from the transmitting coil. Incorporating this magnetic field solution with an equivalent circuit for the inductive link allows us to introduce a power transfer formula that combines coil characteristics and misalignment factors. The coil geometries considered are spiral and short solenoid structures which are currently popular in the RFID and biomedical domains. The novel analytical power transfer efficiency expressions introduced in this study allow the optimization of coil geometry for maximum power transfer and misalignment tolerance. The experimental results show close correlation with the theoretical predictions. This analytic technique can be widely applied to inductive wireless power transfer links without the limitations imposed by numerical methods.

Wireless Power Transfer in Loosely Coupled Links: Coil Misalignment Model

We present a fully differential 128-channel integrated neural interface. It consists of an array of 8 X 16 low-power low-noise signal-recording and generation circuits for electrical neural activity monitoring and stimulation, respectively. The recording channel has two stages of signal amplification and conditioning with and a fully differential 8-b column-parallel successive approximation (SAR) analog-to-digital converter (ADC). The total measured power consumption of each recording channel, including the SAR ADC, is 15.5 ?W. The measured input-referred noise is 6.08 ? Vrms over a 5-kHz bandwidth, resulting in a noise efficiency factor of 5.6. The stimulation channel performs monophasic or biphasic voltage-mode stimulation, with a maximum stimulation current of 5 mA and a quiescent power dissipation of 51.5 ?W. The design is implemented in 0.35-?m complementary metal-oxide semiconductor technology with the channel pitch of 200 ?m for a total die size of 3.4 mm × 2.5 mm and a total power consumption of 9.33 mW. The neural interface was validated in in vitro recording of a low-Mg2+/high-K+ epileptic seizure model in an intact hippocampus of a mouse.

/pdf/the-128-channel-fully-differential-digital-integrated-neural-2de1s1iso7.pdf

The 128-Channel Fully Differential Digital Integrated Neural Recording and Stimulation Interface

This paper reports an integrated 256-channel epiretinal prosthesis integrated circuit (IC). This epiretinal prosthesis system consists of a power telemetry subsystem to deliver 100 mW power, a data telemetry subsystem to transfer 2 Mbps data, digital controllers to decode stimulation patterns, and a 256-channel stimulator to generate user programmable bi-phasic current stimuli. In this study, dual-band telemetry is adopted to achieve both high power efficiency and high data rate. Frequencies of 2 and 22 MHz are chosen for power and data carrier frequencies, respectively. A mixed-mode and multiple-voltage design is applied to the stimulator for withstanding a high-compliance voltage of ± 10 V at the output stage as well as for reducing the area of each pixel. To add flexibility to the stimulator, each pixel has a local digital controller, which enables the stimulator IC to generate 256 parallel stimulations with various pulse widths and amplitudes. The chip is fabricated in TSMC 0.18 μm 32 V CMOS process with 256 area pads constructed above the stimulus current drivers.

An Integrated 256-Channel Epiretinal Prosthesis

This paper presents the design of a system intended to be used as a prosthesis allowing profoundly visually impaired patients to recover partial vision by means of microstimulation in the primary visual cortex area. The main component of the system is a bio-electronic device to be implanted inside the skull of the user, composed of a plurality of stimulation modules, whose actions are controlled via an interface module. Power and data are transmitted to the implant wirelessly through a bidirectional inductive link, allowing diagnosis of the stimulating device and its environment after implantation, as well as power delivery optimization. A high level of flexibility is supported in terms of stimulation parameters, but a configurable communication protocol allows the device to be used with maximum efficiency. The core of an external controller implemented in a system on a programmable chip is also presented, performing data conversion and timing management such that phosphene intensity can be modulated by any parameter defining stimulation, either at the pulse level or in the time domain. Measured performances achieved with a prototype using two types of custom ASICs implemented in a 0.18-mum CMOS process and commercial components fulfill the requirements for a complete visual prosthesis for humans. When on/off activation is used with predefined parameters, stimuli measured on an electronic test bench could attain a rate in excess of 500 k pulses/s.

A Highly Flexible System for Microstimulation of the Visual Cortex: Design and Implementation

We present in this paper a current mediated active pixel sensor (APS) with variable image size and resolution for power saving, electronic zooming, and data reduction at the sensor level. The circuit can perform averaging of output signals in blocks of adjacent pixels (kernels) of size 1/spl times/1, 2/spl times/2 and 4/spl times/4, allowing data reduction without aliasing effects. To achieve this, a current approach is used, thus enabling high speed operation and low power supply capacity. A novel fixed pattern noise (FPN) reduction scheme using a compact circuitry is presented. The circuit compensates for pixel transconductance mismatch in addition to offset error via analog to digital conversion reference current scaling. Hspice simulations using parameters of a 0.35 /spl mu/m CMOS process illustrate the advantage of the new technique over usual correlated double sampling (CDS) in current mode sensors. Parallel integrated analog to digital converters (ADC), a data line-buffer and digital control complete the circuit making data transmission easy and simplifying hardware needed for using the image sensor.

Variable resolution CMOS current mode active pixel sensor

A CMOS image sensor with pixel level analog to digital conversion is presented Each 138/spl mu/m /spl times/ 138/spl mu/m pixel area contains a photodiode and a dynamic comparator using the maximum voltage swing available (0V-18V) The comparator does not need any bias current and is insensitive to fabrication process variations Also a digital to analog converter (DAC) is used to deliver a voltage reference in order to compare it with the pixel voltage for the analog to digital conversion This DAC provides the possibility to convert the pixel voltage linearly or to compress it logarithmically The circuit allows image captures at multiple exposure times, and the resulting values are delivered in floating digital format, offering the possibility to expand the intrascene dynamic range to more than 84 dB The circuit was implemented in a CMOS 018/spl mu/m process and has been submitted for fabrication

A wide dynamic range CMOS digital pixel sensor

High data transfer rates in the order of 1 Mbit/s are now in demand for some inductively powered devices, but communication needs to be made without compromising power transfer and its efficiency. This paper compares different modulation schemes and proposes an interface to satisfy demanding bidirectional transmission needs. New demodulation approaches are used for phase and amplitude modulation and an adapted configurable protocol is presented. A complete integrated system is under design with a submicron technology. A transfer rate of 1.13 Mbit/s has been obtained with a discrete component prototype for amplitude demodulation.

Bidirectional high data rate transmission interface for inductively powered devices

We present an integrated mixed-signal circuit dedicated for electrical stimulation. The chip has 4 channels using 4 electrodes each, to be connected directly on a square 16-electrode matrix. The circuit is designed for maximum flexibility and safety. It allows stimulation to be monopolar as well as bipolar, and uses a configurable communication protocol, reducing the transfer rate requirements according to the stimulation strategy used. Low power is achieved using dual-voltage supply. Finally, to ensure safe stimulation, characterization and troubleshooting after implantation of the chip, voltage monitoring of any of the 16 electrodes is possible using a rail-to-rail amplifier that can be shut-down for lowest power consumption. The circuit has been fabricated and tested in a CMOS 0.18 /spl mu/m process.

http://ieeexplore.ieee.org/iel5/8452/26620/01186845.pdf

J. Coulombe

Papers

A Highly Flexible System for Microstimulation of the Visual Cortex: Design and Implementation

Variable resolution CMOS current mode active pixel sensor

A wide dynamic range CMOS digital pixel sensor

Bidirectional high data rate transmission interface for inductively powered devices

A mixed-signal IC for multiple cortical stimulation strategies