Affiliated with Université Laval & CERVO Research Centre

A fully implantable multichip neural interface with a new scalable current-reuse front-end

TitleA fully implantable multichip neural interface with a new scalable current-reuse front-end
Publication TypeConference Paper
Year of Publication2017
AuthorsRezaei M., Maghsoudloo E., Bories C., De Koninck Y., Gosselin B.
Conference Name2017 15th IEEE International New Circuits and Systems Conference (NEWCAS)
Date PublishedJune
KeywordsAnalog front-end, Binary phase shift keying, Current-reuse amplifier, Electronics packaging, Fully implantable, Inductive power link, Integrated neural interface, Receivers, Transceivers, Transistors, Transmitters, Wireless communication, Wireless transceiver

This paper presents a fully implantable brain machine interface based on a new CMOS system-on-a-chip (SOC) including a low-power multi-channel current-reuse analog front-end (AFE), a multi-band wireless transceiver and a power management unit retrieving power from a 13.56 MHz carrier through a new 5-coil inductive link. In addition to this SOC, the proposed interface includes a low-power microcontroller, a wideband antenna and a double-sided power recovery coil. All components are bonded on a thin flexible printed circuit board. The AFE uses a new current-reuse circuit topology based on a current-mirror opamp which is scalable to very large number of recording channels, thanks to its small implementation area and its low-power consumption. It includes a low-noise amplifier (LNA) and a programmable gain amplifier (PGA) presenting tree selectable gains of 35 dB, 43.1 dB and 49.5 dB. The SOC is fabricated in a CMOS 180-nm process and has a size of 1.3 mm × 1.8 mm. The AFE has a low-power consumption of 9 µW (4.5 µw for LNA and 4.5 µw for PGA) per channel, for an input referred noise of 3.2 µV. A 5-coil wireless power link is utilized with an efficiency of 28% and a maximum power delivered to the load of 81 mW through a 1 cm2 flexible coil. The ultra wideband edge combining BPSK transmitter reaches a maximum data rate of 800 Mbps at 6.7 pJ/bit, and the 2.4-GHz OOK receiver reaches a maximum data rate of 100 Mbps. The whole system consumes 12.3 mW and weights 0.163 g. Finally, we present biological results obtained in-vivo from the cortex of an anesthetized mouse.