Agenda

MSc ME Thesis Presentation

Structured electronic design of high-pass ΣΔ converters and its application to cardiac signal acquisition

Samprajani Rout

Abstract:

With the bandwidth of the ECG signal extending from sub-Hz to 200 Hz, a major challenge in developing the analog front-end responsible for digitizing the analog signal for an ECG readout system lies in implementing the large time-constants on chip due to area constraints. While techniques to obtain very large time constants exist, they are heavily limited by both linearity and accuracy, which clearly dictates the need for alternative structures.

In this thesis, a ΣΔ converter is used for its noise-shaping property to digitize the acquired signal. A structured electronic design methodology based on state-space forms is proposed to develop high-pass (HP) ΣΔ converter topologies. As opposed to conventional low-pass or band-pass ΣΔ, a generalized signal transfer function which includes the high-pass characteristic is used. The proposed HP ΣΔ topologies satisfy the signal transfer function, which is high-pass characteristic in this application and the noise transfer function, which is a 2-nd order noise shaping in this case. Furthermore, the noise contribution of each of the integrators is evaluated and the topologies are compared in terms of their total noise contribution. Finally, one of the structures is implemented in 0.18 um technology as a final step of verification.

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