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Biomedical Circuits and Systems, IEEE Transactions on

Issue 1 • Date Feb. 2009

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Displaying Results 1 - 13 of 13
  • Table of contents

    Publication Year: 2009 , Page(s): C1
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  • IEEE Transactions on Biomedical Circuits and Systems publication information

    Publication Year: 2009 , Page(s): C2
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  • Micropower CMOS Integrated Low-Noise Amplification, Filtering, and Digitization of Multimodal Neuropotentials

    Publication Year: 2009 , Page(s): 1 - 10
    Cited by:  Papers (54)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (752 KB) |  | HTML iconHTML  

    Electrical activity in the brain spans a wide range of spatial and temporal scales, requiring simultaneous recording of multiple modalities of neurophysiological signals in order to capture various aspects of brain state dynamics. Here, we present a 16-channel neural interface integrated circuit fabricated in a 0.5 mum 3M2P CMOS process for selective digital acquisition of biopotentials across the spectrum of neural signal modalities in the brain, ranging from single spike action potentials to local field potentials (LFP), electrocorticograms (ECoG), and electroencephalograms (EEG). Each channel is composed of a tunable bandwidth, fixed gain front-end amplifier and a programmable gain/resolution continuous-time incremental DeltaSigma analog-to-digital converter (ADC). A two-stage topology for the front-end voltage amplifier with capacitive feedback offers independent tuning of the amplifier bandpass frequency corners, and attains a noise efficiency factor (NEF) of 2.9 at 8.2 kHz bandwidth for spike recording, and a NEF of 3.2 at 140 Hz bandwidth for EEG recording. The amplifier has a measured midband gain of 39.6 dB, frequency response from 0.2 Hz to 8.2 kHz, and an input-referred noise of 1.94 muV rms while drawing 12.2 muA of current from a 3.3 V supply. The lower and higher cutoff frequencies of the bandpass filter are adjustable from 0.2 to 94 Hz and 140 Hz to 8.2 kHz, respectively. At 10-bit resolution, the ADC has an SNDR of 56 dB while consuming 76 muW power. Time-modulation feedback in the ADC offers programmable digital gain (1-4096) for auto-ranging, further improving the dynamic range and linearity of the ADC. Experimental recordings with the system show spike signals in rat somatosensory cortex as well as alpha EEG activity in a human subject. View full abstract»

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  • A Wireless Capsule Endoscope System With Low-Power Controlling and Processing ASIC

    Publication Year: 2009 , Page(s): 11 - 22
    Cited by:  Papers (26)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1728 KB) |  | HTML iconHTML  

    This paper presents the design of a wireless capsule endoscope system. The proposed system is mainly composed of a CMOS image sensor, a RF transceiver and a low-power controlling and processing application specific integrated circuit (ASIC). Several design challenges involving system power reduction, system miniaturization and wireless wake-up method are resolved by employing optimized system architecture, integration of an area and power efficient image compression module, a power management unit (PMU) and a novel wireless wake-up subsystem with zero standby current in the ASIC design. The ASIC has been fabricated in 0.18-mum CMOS technology with a die area of 3.4 mm * 3.3 mm. The digital baseband can work under a power supply down to 0.95 V with a power dissipation of 1.3 mW. The prototype capsule based on the ASIC and a data recorder has been developed. Test result shows that proposed system architecture with local image compression lead to an average of 45% energy reduction for transmitting an image frame. View full abstract»

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  • Analysis, Design, and Control of a Transcutaneous Power Regulator for Artificial Hearts

    Publication Year: 2009 , Page(s): 23 - 31
    Cited by:  Papers (36)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1359 KB) |  | HTML iconHTML  

    Based on a generic transcutaneous transformer model, a remote power supply using a resonant topology for use in artificial hearts is analyzed and designed for easy controllability and high efficiency. The primary and secondary windings of the transcutaneous transformer are positioned outside and inside the human body, respectively. In such a transformer, the alignment and gap may change with external positioning. As a result, the coupling coefficient of the transcutaneous transformer is also varying, and so are the two large leakage inductances and the mutual inductance. Resonant-tank circuits with varying resonant-frequency are formed from the transformer inductors and external capacitors. For a given range of coupling coefficients, an operating frequency corresponding to a particular coupling coefficient can be found, for which the voltage transfer function is insensitive to load. Prior works have used frequency modulation to regulate the output voltage under varying load and transformer coupling. The use of frequency modulation may require a wide control frequency range which may extend well above the load insensitive frequency. In this paper, study of the input-to-output voltage transfer function is carried out, and a control method is proposed to lock the switching frequency at just above the load insensitive frequency for optimized efficiency at heavy loads. Specifically, operation at above resonant of the resonant circuits is maintained under varying coupling-coefficient. Using a digital-phase-lock-loop (PLL), zero-voltage switching is achieved in a full-bridge converter which is also programmed to provide output voltage regulation via pulsewidth modulation (PWM). A prototype transcutaneous power regulator is built and found to to perform excellently with high efficiency and tight regulation under variations of the alignment or gap of the transcutaneous transformer, load and input voltage. View full abstract»

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  • Real-Time Classification of Complex Patterns Using Spike-Based Learning in Neuromorphic VLSI

    Publication Year: 2009 , Page(s): 32 - 42
    Cited by:  Papers (35)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1140 KB) |  | HTML iconHTML  

    Real-time classification of patterns of spike trains is a difficult computational problem that both natural and artificial networks of spiking neurons are confronted with. The solution to this problem not only could contribute to understanding the fundamental mechanisms of computation used in the biological brain, but could also lead to efficient hardware implementations of a wide range of applications ranging from autonomous sensory-motor systems to brain-machine interfaces. Here we demonstrate real-time classification of complex patterns of mean firing rates, using a VLSI network of spiking neurons and dynamic synapses which implement a robust spike-driven plasticity mechanism. The learning rule implemented is a supervised one: a teacher signal provides the output neuron with an extra input spike-train during training, in parallel to the spike-trains that represent the input pattern. The teacher signal simply indicates if the neuron should respond to the input pattern with a high rate or with a low one. The learning mechanism modifies the synaptic weights only as long as the current generated by all the stimulated plastic synapses does not match the output desired by the teacher, as in the perceptron learning rule. We describe the implementation of this learning mechanism and present experimental data that demonstrate how the VLSI neural network can learn to classify patterns of neural activities, also in the case in which they are highly correlated. View full abstract»

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  • An Analytical Model for Inductively Coupled Implantable Biomedical Devices With Ferrite Rods

    Publication Year: 2009 , Page(s): 43 - 52
    Cited by:  Papers (17)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1005 KB) |  | HTML iconHTML  

    Using approximations applicable to near field coupled implants simplified expressions for the complex mutual inductance of coaxial aligned coils with and without a cylindrical ferrite rod are derived. Experimental results for ferrite rods of various sizes and permeabilities are presented to verify the accuracy of this expression. An equivalent circuit model for the inductive link between an implant and power coil is then presented and used to investigate how ferrite size, permeability and loss affect the power available to the implant device. Enhancements in coupling provided by high frequency, low permeability nickel zinc rods are compared with low frequency high permeability manganese zinc rods. View full abstract»

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  • Systematic Design and Modeling of a OTA-C Filter for Portable ECG Detection

    Publication Year: 2009 , Page(s): 53 - 64
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2193 KB) |  | HTML iconHTML  

    This study presents a systematic design of the fully differential operational transconductance amplifier-C (OTA-C) filter for a heart activities detection apparatus. Since the linearity and noise of the filter is dependent on the building cell, a precise behavioral model for the real OTA circuit is created. To reduce the influence of coefficient sensitivity and maintain an undistorted biosignal, a fifth-order ladder-type lowpass Butterworth is employed. Based on this topology, a chip fabricated in a 0.18- mum CMOS process is simulated and measured to validate the system estimation. Since the battery life and the integration with the low-voltage digital processor are the most critical requirement for the portable diagnosis device, the OTA-based circuit is operated in the subthreshold region to save power under the supply voltage of 1V. Measurement results show that this low-voltage and low-power filter possesses the HD3 of -48.9 dB, dynamic range (DR) of 50 dB, and power consumption of 453 nW. Therefore, the OTA-C filter can be adopted to eliminate the out-of-band interference of the electrocardiogram (ECG) whose signal bandwidth is located within 250 Hz. View full abstract»

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  • Engineering the Future of Biomedicine

    Publication Year: 2009 , Page(s): 65 - 66
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  • IEEE Transactions on Biomedical Circuits and Systems Information for authors

    Publication Year: 2009 , Page(s): 68
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  • Special issue on therapeutic ultrasound

    Publication Year: 2009 , Page(s): 67
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  • IEEE Transactions on Biomedical Circuits and Systems society information

    Publication Year: 2009 , Page(s): C3
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  • Blank page [back cover]

    Publication Year: 2009 , Page(s): C4
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Aims & Scope

IEEE Transactions on Biomedical Circuits and Systems (TBioCAS) publishes peer-reviewed manuscripts reporting original and transformative research at the intersection between the life sciences and circuits and systems engineering principles.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Gert Cauwenberghs
University of California at San Diego