A 28-μW EEG readout front-end utilizing a current-mode instrumentation amplifier and a source-follower-based LPF
ABSTRACT A novel low-power EEG readout front-end featuring a current-mode instrumentation amplifier (CMIA) followed by a 4th-order gain-compensated source-follower-based lowpass filter (LPF) is proposed. The CMIA is of current-conveyor topology and is chopper-stabilized to improve the common-mode noise rejection and suppress the dc-offset and 1/f noise. The typical gain-loss problem of source-follower-based LPF is alleviated by adopting a gain-compensation technique. Optimized in 0.35-μm CMOS, the achieved CMRR is >100 dB from 0.01 to 16 Hz, and >90 dB up to 40 Hz. With the chopper stabilization, the noise voltage density is 248 nV√Hz at 0.01 Hz and 197 nV√Hz at 100 Hz. The power consumption is 28 μW at 3 V.
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ABSTRACT: A novel ultra low power, area-efficient, current-mode instrumentation amplifier (CMIA) with embedded bandpass filter, for acquisition of bio-potential signals is presented. A novel bias front-end is also presented, which achieves CMRR of 195dB at 1Hz in the presence of ±5% component mismatch. The CMIA has a tunable bandwidth, from 160Hz to 7.2kHz with input referred rms noise of 2.24 μV in frequency band of 5mHz to 160Hz. The CMIA is designed in 180nm mixed-mode CMOS technology and provides rail to rail output voltage of 1.65V(p-p) while dissipating 39 μW, at 1.8V supply voltage. The output of CMIA doesn't need any further signal conditioning.Quality Electronic Design (ISQED), 2013 14th International Symposium on; 01/2013