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 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 27 Issue: 7
  • Publication Date: 2019
  • Doi Number: 10.1109/tvlsi.2019.2898873
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • 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
  • Middle East Technical University Affiliated: Yes


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.