Low power low noise bio-amplifier with adjustable gain for digital bio-signals acquisition systems

This work describes a symmetrical power supplied (±1.8 V) 0.5 μm CMOS implementation of a bio-amplifier designed for use in digital acquisition systems. The whole acquisition system under fabrication will still contain a 3^rd order switched capacitor anti-alias eliptic filter, a sample and hold, an ADC and a SPI interface. In this paper though the focus is over the analog circuitry responsable of amplifing the bio-signals. The achievable gains are controlled through a switched capacitor technique and can achieve over 70 dB with 2.5 μV_RMS of input referred noise within 1.5 kHz bandwith. The circuit dissipates 33.2 μW in 0.192 mm².