A multi-channel EEG system featuring single-wire data aggregation via FM-FDM techniques

Conventional EEG systems are extremely power hungry due to a reliance on high resolution analog-to-digital converters (ADCs) to cover their required dynamic range. This paper presents a novel architecture for acquiring multi-channel high-resolution EEG using low power techniques. Instead of digitizing the output of each analog front-end (AFE) amplifier with an individual ADC, a voltage-controlled oscillator is used to generate an up-converted frequency-modulated (FM) signal at a unique carrier frequency. All channels then share a single wire via frequency-domain multiplexing (FDM), enabling a rugged mechanical design. The composite FM signal is then digitized with a single ADC optimized for time-domain resolution (1 MHz, 12 bits) rather than employing multiple ADCs optimized for voltage-domain resolution (1 kHz, 16–24 bits), thereby enabling a low-power implementation. To validate this approach, a discrete prototype is developed and achieves 75 dB of dynamic range per channel.