A low noise bandpass neuro-amplifier with adjustable bandwidth for bio-medical applications

This paper presents a design and experimental results of a bio-potential amplifier design with a noise filtering capability. The amplifier is operated in the subthreshold region for micro-volt neuron signal sensing, amplification, and filtering. The amplification provides 10 K-Hz bandwidth with tunable cutoff sensing frequencies from 0 Hz to 500 Hz and 6KHz to 10 KHz adjustable range at high frequencies. The amplifier is experimentally validated and was fabricated using a 0.35 um 2P4M mixed-signal polycide process, and has a 70 dB pass-band gain, and 105 uVrms measured noise at negligible load and 88 uVrms with a 2pF active probe loading. The performance characteristics of bio-potential recording amplifiers are compared with the proposed design. The proposed design has reduced the bio-potential amplifier complexity significantly due to the tunnable pico-amphere feedback network but with the cost of increased input referred noise for transistors operated in the subthreshold region.