Fully Implantable Cochlear Implant Interface Electronics With 51.2-mu W Front-End Circuit

Ulusan H. , Chamanian S., Ilik B., Muhtaroglu A., KÜLAH H.

IEEE TRANSACTIONS ON VERY LARGE SCALE INTEGRATION (VLSI) SYSTEMS, vol.27, no.7, pp.1504-1512, 2019 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 27 Issue: 7
  • Publication Date: 2019
  • Doi Number: 10.1109/tvlsi.2019.2898873
  • Page Numbers: pp.1504-1512
  • Keywords: Fully implantable cochlear implant (FICI), hearing loss, logarithmic amplifier (LA), neural stimulation, piezoelectric (PZT) sensor, ultralow power, VOLTAGE, DESIGN, SENSOR, RANGE, NOISE


This paper presents an ultralow power interface circuit for a fully implantable cochlear implant (FICI) system that stimulates the auditory nerves inside cochlea. The input sound is detected with a multifrequency piezoelectric (PZT) sensor array, is signal-processed through a front-end circuit module, and is delivered to the nerves through current stimulation in proportion to the sound level. The front-end unit reduces the power dissipation by combining amplification and compression of the sensor output through an ultralow power logarithmic amplifier. The amplified signal is envelope detected, and fed to a voltage-controlled current source as a reference for stimulation current generation. The single channel performance has been tested with a thin film pulsed-laser deposition (PLD) PZT sensor for sound levels between 60- and 100-dB sound pressure level (SPL). The proposed front-end signal conditioning unit, which can support different back-end stimulators, dissipates only 25.4 and 51.2 mu W based on measurement, for 1- and 8-channel operation, respectively. This represents the lowest in the literature. The interface generates linear stimulation current of 110-430 mu A for the given sound range. The single-channel and eight-channel stimulator consume 105 and 691 mu W, respectively, for 110-mu A biphasic stimulation current.