Abstract

SPINELLI, E. M.  and  MAYOSKY, M. A.. Mixed-signal design of biopotential front-ends. Lat. Am. appl. res. [online]. 2010, vol.40, n.2, pp.99-103. ISSN 1851-8796.

High resolution Sigma-Delta Analog-to-Digital Converters (SDADC) have drastically changed traditional analog signal processing stages. However, as the boundary between analog and digital worlds becomes diffuse, a "mixed-signal processing" approach arises. For instance, analog filters, traditionally implemented as independent processing stages can be easily incorporated in the design of the Sigma-Delta converter, resulting in a more compact approach, with important advantages regarding size and power consumption. In this context, a design technique for mixed-signals front-ends intended for biomedical signals is presented here. As an example, the design of an ECG front-end is presented. It accepts DC offsets of 1300mV, presents an AC input range of 110mV, a -3 dB bandwidth of 100Hz and a total noise less than 10µVp-p, operating at a clock frequency of 57kHz. The front-end provides "fast baseline recovery" features and its transient response fulfills the AAMI standard. A functional prototype was built and tested, validating the design procedure.

Keywords : Biopotential Amplifier; AAMI Standard; Sigma Delta Converter; Mixed Signal Processing.

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