4-Channel asynchronous bio-potential recording system

We present a 4-channel bio-potential recording system using asynchronous delta analog-to-digital converter. The system is designed to reduce the amount of data in neuro-physiological sensors. The circuit includes low-power low-noise amplifiers with asynchronous delta modulators. The analog front end offers a gain of 53dB within bandwidth of 200Hz-20kHz. In this asynchronous data converter, the minimum input-referred delta resolution is 4μV. The input-referred rms noise is 2μV. T h e system was fabricated with AMI 0.5μm CMOS technology. The chip size is 1.5mm by 1.5mm. The power consumption of the 4-channel system with 3.3V supply is 118.8μW in static state and 501.6μW with 240kbps data conversion rate. A graphic user interface was developed to monitor the transmitted signal in real time.