A 1.8 μW 32 nV/√Hz current-reuse capacitively-coupled instrumentation amplifier for EEG detection

This paper presents a capacitively-coupled chopper instrumentation amplifier (CCIA) for portable EEG detection devices. In this design, the current-reuse technology is adopted in the core amplifier and the ripple reduction loop (RRL) to cut down the power consumption of the whole system. A novel ripple reduction loop based on ping-pong auto-zeroing topology is proposed to reduce the ripple at the output of the CCIA. It makes the chopping ripple be attenuated about 46 dB. This system is simulated in a 0.18 μm CMOS process. Simulation results show that the proposed CCIA achieves an equivalent input noise power spectrum density (PSD) of 32 nV/VHz, a noise efficiency factor (NEF) of 1.7, CMRR of 90 dB. The overall current consumption is 1.8 μΑ at a 1V supply.