Low Power Low Noise Neural Amplifier with Adjustable Gain

This work describes a 0.5 μm CMOS implementation of a Folded Cascode OTA designed for minimum Input Referred Noise for non-implantable EEG SoC arrays. It is also described a small area PID feedback network using a high resistive pMOS pseudo-resistor and small integration capacitances for programmable gain control throughout parasitic insensitive nMOS switches. Simulation results show that it achieves about 2.2 μVrms of input referred noise for 6 μA of total current at ±1.8 V supply voltage. The circuit provides a NEF of 4.55 within a 1.96 kHz bandwidth and midband gain of 40.22 dB.