A 1-V 99-to-75dB SNDR, 256Hz–16kHz bandwidth, 8.6-to-39µW reconfigurable SC ΔΣ Modulator for autonomous biomedical applications

The paper presents a reconfigurable Delta-Sigma Modulator (ΔΣM) suitable for three operation modes, whose application ranges from bio-potential signal monitoring to hearing aids. A feed-forward 2nd-order SC ΔΣM architecture with 4-bit quantizer is selected according to an analytic power optimization procedure. The ΔΣM features programmable sampling capacitors in the first integrator and novel reconfigurable power-gated OTAs to adjust power consumption in each operation mode. An asynchronous embedded SAR converter implements low-power quantization and passive addition in the feed-forward topology. The prototype is implemented in a 0.18μm CMOS technology and operates from a supply voltage of 1V. Measurements show peak SNDRs from 99 to 75dB for signal bandwidths spanning from 256Hz to 16kHz, achieving figures of merit which are almost constant in the different modes, and range from 0.20 to 0.27pJ/c.s.