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Compressive Sensing system for recording of ECoG signals in-vivo

Compressive Sensing system for recording of ECoG signals in-vivo

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successive <strong>in</strong>tegration w<strong>in</strong>dows <strong>in</strong> order to develop a Parallel Segmented CS (PSCS)architecture, which achieves a decreas<strong>in</strong>g <strong>in</strong> the necessary number <strong>of</strong> implemented paths perchannel.Figure B.2.1.1. Circuit implementation <strong>of</strong> the proposed CS receiver.By exploit<strong>in</strong>g signal sparsity, the <strong>system</strong> accomplishes 44 dB overall SNRD, with a powerconsumption <strong>of</strong> 120.8 mW. Others critical specifications about the design have been <strong>in</strong>cluded <strong>in</strong>Table B.2.1.1.ParameterSpecificationTechnology90 nm CMOSParallel paths 8Chip area (8 paths)1000 μm x 1400 μmBandwidth (BW f )10 MHz - 1.5 GHzTable B.2.1.1. CS model specifications.B.2.2. Voltage ModeIn [3], Chen and Chandrakasan have proposed a voltage mode-based architecture <strong>for</strong> ananalog channel <strong>for</strong> a wireless neural CS implementation which has been depicted <strong>in</strong> Fig.B.2.2.1.The registered signal is amplified by an operational transconductance ampliflier (OTA) <strong>in</strong> each<strong>of</strong> the M paths <strong>of</strong> the CS operation, and afterwards, the N samples are multiplied by Ncoefficients <strong>of</strong> the random matrix and accumulated <strong>in</strong> each <strong>of</strong> the rows be<strong>for</strong>e be<strong>in</strong>g sent atcompressed rate to the dedicated ADC which has been <strong>in</strong>cluded <strong>in</strong> each <strong>of</strong> the paths. At theoutput <strong>of</strong> each <strong>of</strong> the ADC the f<strong>in</strong>al digitized compressed value is acquired. The exploit <strong>of</strong> oneamplifier per channel widely <strong>in</strong>crease the power consumption as it is shown <strong>in</strong> the Eq.24. In theChapter 3.3 the necessity <strong>of</strong> one OTA and ADC per path are deeply discussed <strong>in</strong> order to clarifythe feasibility <strong>of</strong> an analog implementation <strong>for</strong> a neural channel.77

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