A 74-μW 11-Mb/s Wireless Vital Signs Monitoring SoC for Three-Lead ECG, Respiration Rate, and Body Temperature

This paper presents a wireless vital signs monitoring system-on-chip including three-lead ECG, bio-impedance (Bio-Z) and body temperature. A Bio-Z readout channel with early demodulation is introduced to detect small body impedance change below 300 mΩ under large baseline resistance while consuming power of 9.8 μW. A direct temperature-to-digital converter is also incorporated, which achieves an absolute resolution of 0.023 °C and inaccuracy less than ±0.13 °C over temperature range of 32-42 °C. The quantized vital sign signal is transmitted through a multi-channel reconfigurable QPSK/BFSK transmitter (TX) to accommodate different power-constraint scenarios. Fabricated in 130-nm CMOS technology with a total die area of 6.25 mm², the proposed SoC only consumes 74 μW under 0.9-V supply.