A highly linear, Sigma-Delta based, sub-Hz high-pass filtered ExG readout system

Integrating time constants of the order of a few seconds is one of the main bottlenecks in the design of biomedical chips. To achieve a low cut-off frequency with 60 dB linearity, mixed-signal feedback utilizing the properties of a ΣΔ ADC is proposed. To verify the performance, a 10-bit ΣΔ modulator with the proposed technique is designed to be implemented in 0.18 μm CMOS AMS technology. The design is verified by means of simulations in Cadence using RF spectre.