Integrated programmable analog front-end architecture for physiological signal acquisition

A versatile front-end capable of acquiring a wide range of physiological signals, thus reusing the same design and hardware in different contexts, is a valuable goal both for biomedical research and medical devices. In this work we present such an "all-terrain" programmable integrated front-end architecture and the trade-offs associated to its design. A low noise preamplifier is implemented using a novel architecture based on a differential-difference amplifier which applies gm-C techniques for fixing the cut-off frequencies. Moreover, this architecture is extended to be applied to the other stages of the front-end. The main design trade-offs (noise-power, gain-power, noise-gain and linearity-gain) of the front-end architecture are discussed and their impacts in the design of the processing chain in terms of assignment of gain, noise, linearity and programmability to each stage are shown. The front-end is designed in a 0.5 mu m CMOS process. The gain is programmable between 57dB and 99dB, the high cut-off frequency is programmable between 116Hz and 5.2 kHz, the low cut-off frequency is 18Hz, the maximum power consumption of the front-end is 11.2 mu A and its maximum equivalent input-referred noise voltage is 1.87 mu V-rms.