ABSTRACT
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.
Subject(s)
Body Temperature/physiology , Electrocardiography , Respiratory Rate/physiology , Signal Processing, Computer-Assisted , Wireless Technology , Adult , Humans , MaleABSTRACT
An 8-channel wireless neural signal processing IC, which can perform real-time spike detection, alignment, and feature extraction, and wireless data transmission is proposed. A reconfigurable BFSK/QPSK transmitter (TX) at MICS/MedRadio band is incorporated to support different data rate requirement. By using an Exponential Component-Polynomial Component (EC-PC) spike processing unit with an incremental principal component analysis (IPCA) engine, the detection of neural spikes with poor SNR is possible while achieving 625× data reduction. For the TX, a dual-channel at 401 MHz and 403.8 MHz are supported by applying sequential injection locked techniques while attaining phase noise of -102 dBc/Hz at 100 kHz offset. From the measurement, error vector magnitude (EVM) of 4.60%/9.55% with power amplifier (PA) output power of -15 dBm is achieved for the QPSK at 8 Mbps and the BFSK at 12.5 kbps. Fabricated in 65 nm CMOS with an active area of 1 mm 2, the design consumes a total current of 5 â¼ 5.6 mA with a maximum energy efficiency of 0.7 nJ/b.
