Structured electronic design of high-pass ΣΔ converters and their application to cardiac signal acquisition
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Abstract
Achieving an accurate sub-Hz high-pass (HP) cutoff frequency and simultaneously a high accuracy of the transfer function is a challenge in the implementation of analog-to-digital converters for biomedical ExG signals. A structured electronic design approach based on state-space forms is proposed to develop HPΣΔ modulators targeting high accuracy of the HP cutoff frequency and good linearity. Intermediate transfer functions are mathematically evaluated to compare the proposed HPΣΔ topologies with respect to dynamic range. Finally, to illustrate the design method, an orthonormal HPΣΔ modulator is designed to be implemented in 0.18 μm technology which achieves a linearity of 12-bits.