Iranian Journal of Biomedical Engineering (IJBME)
نشریه علمی مهندسی پزشکی زیستی

Design and Simulation of the Data and Power Recovery Blocks of an Inductively-Powered Microsystem Dedicated to a Brain Implant

Document Type : Full Research Paper

Authors

Zahra-Sadat Fatemi 1
Mohammad Mahdi Ahmadi 2

1 M.Sc. Student, Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran

2 Assistant Professor, Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran

https://doi.org/10.22041/ijbme.2018.91673.1393
Abstract
The use of smart medical implants to study the human brain and the interaction of neurons with each other has recently gained much attention. These implants contain microelectrode arrays in which the size of an electrode is in the order of the size of a neuron; therefore they allow recording signals from single neuron or stimulating a single neuron with considerable precision. Design of such implants entails many challenges, one of which is the design of power and data recovery blocks. In this paper, we describe the design of a new power and data recovery unit for an implantable neural stimulating microsystem. The power recovery unit generates two supply voltages: a 1.8-V supply for the core circuits and a higher supply voltage for the stimulation front-end. An active rectifier is used to generate the 1.8-V supply. The active rectifier achives a 89% power conversion efficiency and 150mV voltage drop with a 3-V sinusoidal input voltage. In order to maximize the efficiency of the stimulation front-end, the supply voltage of that circuit should be adaptively adjusted according to the amplitude of the stimulation current. As a result, a phase-controlled active rectifier is utilized to generate the supply voltage for the neural stimulation front-end. The phase-controlled active rectifier can generate out voltages ranging from 1.8V to 2.5V. Using phase-controlled active rectifier can increase the power conversion efficiency up to 50%. In addition to power recovery, neuroelectrical stimulation microsystems should receive stimulation data from outside of the body. Hence, this paper also circuits required for clock and daterecovery. The data recovery block is able to demodulate the ASK-modulated signal with 3-V to 5-V amplitude and 5% to 25% modulation index.

Keywords

Implantable Microsystems
Electrical Stimulation
Wireless Power Transfer
Active Rectifier
Phase Controlled Active Rectifier
Clock and Data Recovery

Subjects

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Iranian Journal of Biomedical Engineering (IJBME)
Volume 12, Issue 3
Autumn 2018
Pages 221-234

  • Receive Date 10 August 2018
  • Revise Date 01 October 2018
  • Accept Date 29 October 2018

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