A 700-uW Wireless Sensor Node SoC for Continuous Real-Time Health Monitoring

Abstract

A low-power low-voltage system on a chip (SoC) was designed and implemented in a 0.18-mu m CMOS process to provide a fully integrated sensor node solution for wearable wireless health monitoring. The SoC contains a sensor interface circuit, an analog-to-digital converter, a digital signal processor and a radio-frequency transmitter. Only a minimal number of off-chip components, which include an antenna, a crystal and supply decoupling capacitors, are used for improved user experience and affordability. The sensor node developed was demonstrated together with the prototype personal server. The acquired electrocardiogram ( ECG) signal could be reliably transmitted to and monitored by the personal server over a distance greater than 5 m. The SoC consumes only 700 mu W at 0.7-V supply voltage when it acquires ECG signal from the patient and transmits it through the 433.92-MHz channel with an output power of -16 dBm. This low-power sensor node solution enables continuous and real-time health monitoring for more than 200 hours without changing the battery, when a typical button-cell battery (e.g., CR2032) is used.