A wireless implantable multichannel digital neural recording system for a micromachined sieve electrode

This paper reports the development of an implantable, fully integrated, multichannel peripheral neural recording system, which is powered and controlled using an RF telemetry link. The system allows recording of ±500 μV neural signals from axons regenerated through a micromachined silicon sieve electrode. These signals are amplified using on-chip 100 Hz to 3.1 kHz bandlimited amplifiers, multiplexed, and digitized with a low-power (<2 mW), moderate speed (8 μs/b) current-mode 8-b analog-to-digital converter (ADC). The digitized signal is transmitted to the outside world using a passive RF telemetry link. The circuit is implemented using a bipolar CMOS process. The signal processing CMOS circuitry dissipates only 10 mW of power from a 5-V supply while operating at 2 MHz and consumes 4×4 mm² of area. The overall circuit including the RF interface circuitry contains over 5000 transistors, dissipates 90 mW of power, and consumes 4×6 mm² of area