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  • Journal article
    Constandinou TG, Georgiou J, 2009,

    A Micropower Tilt Processing Circuit

    , IEEE Transactions on Biomedical Circuits and Systems, Vol: 3, Pages: 363-369, ISSN: 1932-4545

    This paper describes a novel analogue circuit for extracting the tilt angle from the output of a linear MEMS accelerometer. The circuit uses the accelerometer signal together with the gravitational acceleration vector to generate the tilt signal. Using a current-mode representation with MOS devices operating in weak inversion, the appropriate trigonometric function has been realised to compute tilt. Furthermore, implementing a long-time constant filter to extract the mean tilt level provides adaptation to the static tilt level. Specifically, this circuit has been designed as part of an implantable vestibular prosthesis to provide inclination signals for bypassing dysfunctional otolith end-organs. The circuit has been fabricated in AMS 0.35um 2P4M CMOS technology and this paper presents the theory, implementation and measured results.

  • Book
    Constandinou TG, 2009,

    Biologically Inspired Electronics for Micropower Vision Processing

    , Publisher: VDM Verlag, ISBN: 978-3639133912
  • Conference paper
    Eftekhar A, Constandinou TG, Abbruzzese D, Woods V, Triantis IF, Drakakis EM, Toumazou Cet al., 2009,

    A Programmable Neural Interface for Investigating Arbitrary Stimulation Strategies

    , 14th Annual International FES Society Conference
  • Conference paper
    Constandinou TG, Georgiou J, Toumazou C, 2009,

    A Neural Implant ASIC for the Restoration of Balance in Individuals with Vestibular Dysfunction

    , IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 641-644
  • Conference paper
    Liu Y, Georgiou P, Constandinou TG, Garner D, Toumazou Cet al., 2009,

    An Auto-Offset-Removal circuit for chemical sensing based on the PG-ISFET

    , IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 1165-1168
  • Conference paper
    Constandinou TG, Georgiou J, 2008,

    A Micropower Tilt Processing Circuit

    , IEEE Biomedical Circuits and Systems (BioCAS) Conference, Publisher: IEEE, Pages: 197-200

    This paper describes a novel analogue circuit for extracting the tilt angle from the output of a standard MEMS accelerometer. The circuit uses the accelerometer signal together with the gravitational acceleration vector to generate the tilt signal. Using a current-mode representation with devices operated in subthreshold, the appropriate trigonometric function has been realised to compute tilt. Furthermore, implementing a long-time constant filter to extract the mean tilt level provides adaptation to the static tilt level. Specifically, this circuit has been designed as part of an implantable vestibular prosthesis to provide inclination signals for bypassing dysfunctional otolith end-organs. The hardware has been implemented in AMS 0.35 mum 2P4M CMOS technology.

  • Journal article
    Constandinou TG, Georgiou J, 2008,

    A Micropower Arcsine Circuit for Tilt Processing

    , Electronics Letters, Vol: 44, Pages: 1336-1338, ISSN: 0013-5194

    This letter describes an analogue circuit for producing an arcsine transfer based on a differential pair with source degeneration. The application uses this circuit to post-process an accelerometer signal by normalising with respect to the gravitational acceleration vector to extract inclination. Using diode-connected MOS devices operating in weak inversion, the appropriate trigonometric function, i.e. an arcsine, has been realised to compute tilt. The hardware has been implemented in AMS 0.35μm 2P4M CMOS technology.

  • Journal article
    Constandinou TG, Georgiou J, Toumazou C, 2008,

    A Partial-Current-Steering Biphasic Stimulation Driver for Vestibular Prostheses

    , IEEE Transactions on Biomedical Circuits and Systems, Vol: 2, Pages: 106-113, ISSN: 1932-4545

    This paper describes a novel partial-current-steering stimulation circuit for implantable vestibular prostheses. The drive hardware momentarily delivers a charge-balanced asymmetric stimulus to a dummy load before steering towards the stimulation electrodes. In this fashion, power is conserved while still gaining from the benefits of current steering. The circuit has been designed to be digitally programmable as part of an implantable vestibular prosthesis. The hardware has been implemented in AMS 0.35μm 2P4M CMOS technology.

  • Journal article
    Constandinou TG, Georgiou J, Toumazou C, 2008,

    Micropower front-end interface for differential-capacitive sensor systems

    , Electronics Letters, Vol: 44, Pages: 470-472, ISSN: 0013-5194

    A front-end circuit for interfacing to differential capacitive sensors, including certain microelectromechanical systems, is presented. The system combines a self-resetting, biphasic integrator with a difference timer, producing a word parallel output representing the differential capacitance. The measurable capacitance range is tunable by means of an input current bias and system clock frequency. For an input bias of 10 nA and system clock of 128 KHz, the measurable capacitance range is +/-5pF (to 8 bit resolution) consuming below 26 µW total system power.

  • Conference paper
    Prodromakis T, Georgiou P, Constandinou TG, Michelakis K, Toumazou Cet al., 2008,

    Batch Encapsulation Technique for CMOS based Chemical Sensors

    , IEEE Biomedical Circuits and Systems (BioCAS) Conference, Publisher: IEEE, Pages: 321-324
  • Journal article
    Constandinou TG, Georgiou J, 2008,

    Micro-Optoelectromechanical Tilt Sensor

    , Journal of Sensors, Pages: 1-7, ISSN: 1687-725X

    This paper presents a novel hybrid CMOS/MEMS tilt sensor with a 5∘ resolution over a 300∘ range. The device uses a MEMS-based semicircular mass suspended from a rigid body, projecting a shadow onto the CMOS-based optical sensor surface. A one-dimensional photodiode array arranged as a uniformly segmented ring is then used to determine the tilt angle by detecting the position of the semicircular mass. The complete sensor occupies an area of under 2.5 mm × 2.5 mm.

  • Journal article
    Constandinou TG, Georgiou J, Toumazou C, 2008,

    Towards an Integrated, Fully-Implantable Vestibular Prosthesis for Balance Restoration

    , Journal of Advances in Science and Technology, Vol: 57, Pages: 210-215

    Neuroprosthetics is a relatively new topic but it has already shown its potential. Since the application of this science, it has already significantly improved the quality of life of over 60,000 individuals who previously suffered from severely impaired hearing or total deafness. Today, through use of cochlear implants, children born totally deaf can enjoy going to regular schools and communicating normally. Individuals suffering from dizziness and balance disorders can also benefit from the progress made in cochlear prosthetics. The inner ear's vestibular system provides cues about self-motion and help stabilise vision during movement. Damage to this system can result in dizziness, imbalance, blurred vision and instability in locomotion, a leading cause of death in the elderly. We propose a hybrid CMOS/MEMS platform for bypassing a dysfunctional pathway in individuals that suffer from balance-related disorders. Combining MEMS-based inertia sensing with CMOS-based neural monitoring and processing electronics, this prosthesis aims to deliver a corrective artificial stimulus to the vestibulocochlear (VIII) nerve. We describe a novel system outlining the architectural aspects and implementation methodology used in the design.

  • Conference paper
    Constandinou TG, Georgiou J, Andreou C, 2008,

    An Ultra-Low-Power Micro-Optoelectromechanical Tilt Sensor

    , IEEE International Symposium on Circuits and Systems (ISCAS), Pages: 3158-3161
  • Conference paper
    Constandinou TG, Georgiou J, Toumazou C, 2008,

    A Micropower Front-end Interface for Differential-Capacitive Sensor Systems

    , IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 2474-2477
  • Conference paper
    Constandinou TG, Georgiou J, Toumazou C, 2008,

    A Partial-Current-Steering Biphasic Stimulation Driver for Neural Prostheses

    , IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 2506-2509
  • Conference paper
    Constandinou TG, Georgiou J, Toumazou C, 2008,

    A Fully-Integrated Semicircular Canal Processor for an Implantable Vestibular Prosthesis

    , IEEE International Conference on Electronics, Circuits and Systems (ICECS), Publisher: IEEE, Pages: 81-84
  • Journal article
    Lande TS, Constandinou TG, Burdett A, Toumazou Cet al., 2007,

    Running cross-correlation using bitstream processing

    , Electronics Letters, Vol: 43, Pages: 1181-1183, ISSN: 0013-5194

    A novel architecture for running cross-correlation and convolution using bitstream processing is proposed. The computationally intensive multiplications inherent in cross-correlation and convolution are replaced by simple logic operations (AND XOR) using bitstream representation. The reduced complexity enables compact and energy efficient silicon solutions suitable for small, portable devices such as wearable heartbeat detecting electronics embedded in the actual ECG patch.

  • Journal article
    Triantis IF, Woods V, Eftekhar A, Georgiou P, Constandinou TG, Drakakis EM, Toumazou Cet al., 2007,

    Advances in Neural Interfacing

    , IEEE Circuits and Systems Society Newsletter, Vol: 1
  • Conference paper
    Eftekhar A, Constandinou TG, Triantis IF, Toumazou C, Drakakis EMet al., 2007,

    Towards a Reconfigurable Sense-and-Stimulate Neural Interface Generating Biphasic Interleaved Stimulus

    , 3rd International IEEE/EMBS Conference on Neural Engineering (CNE), Publisher: IEEE, Pages: 438-441
  • Conference paper
    Li X, Constandinou TG, Eftekhar A, Georgiou P, Toumazou Cet al., 2007,

    Towards a bionic neural link for implantable prosthetics

    , IEEE EMBS Conference on Neural Engineering, Publisher: Institute of Electrical and Electronics Engineers (IEEE), Pages: 85-88

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