A wireless FM multi-channel microsystem for biomedical neural recording applications

This paper presents a four-channel wireless microsystem, suitable for a variety of biomedical neural recording applications. The neural recording circuitry features onchip AC amplification, DC rejection, clock generation, time-division-multiplexing, and frequency modulation with RF carrier frequency tunable in the 88-108 MHz commercial FM band. A wide-band FM radio followed by a LabView-based system is utilized for demodulation and de-multiplexing to re-construct the original input data. This system consists of a 2.2 mm×2.2 mm integrated circuit and four off-chip components (1 inductor and 3 capacitors) that are wire bonded to the chip. It measures 1.8×1.3×0.16 cm³, weighs 1.1 g including two 1.5 V batteries, and dissipates less than 2.5 mW from a 3 V power supply. The chip is fabricated using AMI 1.5 μm double-poly double-metal n-well CMOS process. Benchtop tests show complete functionality of the wireless microsystem in both ambient light and dark conditions.