Overview
A 24-bit sigma-delta analogue acquisition system designed for dry-electrode EEG headset applications, resolving microvolt-level neural signals in high-interference environments.
- High-resolution sigma-delta ADC with fully differential input stage and instrumentation amplifier topology.
- Maximised input impedance to maintain signal quality with dry electrodes under high contact resistance.
- Integrated driven-right-leg circuitry for active interference suppression.
- Programmable gain amplification to accommodate the wide dynamic range of EEG signals.
- Embedded ARM Cortex-M processor managing acquisition timing, digital filtering, and USB data streaming.
- Validated against clinical reference recordings with a PC-side Python acquisition library and visualisation tool.
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Challenge
Resolving microvolt-level neural signals in severe power-line interference without active shielding.
Solution
Developed a 24-bit sigma-delta system with ultra-low-noise instrumentation amplifiers, strict differential path matching, and isolated linear regulators.
Outcome
Delivered a wearable EEG headset with SNR exceeding 110 dB, capturing high-fidelity cortical signals in non-shielded environments.