An ultra low-power chopper stabilized front-end for multichannel cortical signals recording

The design of an ultra low-power CMOS chopper stabilized front-end suitable for a fully implantable cortical data acquisition system (CDAS) is presented The proposed low-power front-end improves recording quality and is area efficient. It removes low frequency noise and achieves submicrovolt input offset. The key to its performances is chopper modulation technique, usage of weakly inverted transistors and a supply voltage of 0.9 V. The chopper amplifier is composed of a low-noise preamplifier combined with a 2^nd order micropower bandpass Gm-C filter. The preamplifier achieves an input referred noise of less than 30 nV/√Hz. A whole channel dissipates less than 20 μW and has been implemented in 0.18 μm CMOS.