Andreas Demosthenous

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—Two prior-art transconductance amplifier-based rail-to-rail class-AB analog buffers are examined. Their analysis reveals that the output current drive capability for large input voltages is restricted. To mitigate this drawback, a relatively simple slew-rate enhancement scheme is proposed. The new scheme allows the buffer's speed to be increased by over(More)
We present a neural stimulator chip with an output stage (electrode driving circuit) that is fail-safe under single-fault conditions without the need for off-chip blocking-capacitors. To miniaturize the stimulator output stage two novel techniques are introduced. The first technique is a new current generator circuit reducing to a single step the(More)
—This paper describes the design of an adaptive control system for recording neural signals from tripolar cuff electrodes. The control system is based on an adaptive version of the true-tripole amplifier configuration and was developed to compensate for possible errors in the cuff electrode balance by continuously adjusting the gains of the two differential(More)
Two integrated nerve stimulator circuits are described. Both generate passively charge-balanced biphasic stimulating pulses of 1 to 16 mA with 10-¿s to 1-ms widths from 6- to 24-V supplies for implanted book electrodes. In both circuits, the electrodes are floating during the passive discharge anywhere within the range of the power rails, which may be up to(More)
The noise from Pt electrodes has not been measured before. We measured the impedance and noise between pairs of Pt electrodes in cylindrical cells within frequency bands which contain the electroneurogram band (ENG, 500-10 kHz). The results show that the noise from the Pt-saline interface and also the volume conductor are the same as the thermal noise from(More)
This paper presents a multichannel stimulator ASIC for an implantable vestibular prosthesis. The system features versatile stimulation management which allows fine setting of the parameters for biphasic stimulation pulses. To address the problem of charge imbalance due to rounding errors, the digital processor can calculate and provide accurate charge(More)