Design of low noise low power biopotential tunable amplifier using voltage controlled pseudo-resistor for biosignal acquisition applications

The development of the large scale multi-electrode neural-recording systems has accelerated the process of brain monitoring. Neural amplifier is the most important development in this field. A fully integrated low-noise tunable neural amplifier is presented in this paper. The proposed neural amplifier not only provides low signal distortion and high output swing but also ensures good linearity over the entire frequency band of interest. Tunability of the resistance is obtained with the help of variable Vref. The amplifier is designed in standard 90nm CMOS process technology using 1V supply voltage. The simulated result shows an input-referred noise of 1.2μV_rms to 0.05μV_rms for the frequency range of 5.2 Hz to 540 KHz. A noise efficiency factor (NEF) of 2.89, with full output swing is obtained.