Ultra Low-Power Sensor Node for Wireless Health Monitoring System

Ultra low power sensor node for wireless health monitoring system was designed and implemented in 0.18-μm CMOS. The sensor node functions as an interface circuit to both sensor and RF transceiver. The sensor node consists of an amplifier, an ADC (analog-to-digital converter) as well as digital system. The digital system is embedded with DSP (digital signal processing) for heart rate processing and RF interface for transceiver. The sensor node draws a total current of 7.5-μA from a 0.9-V single supply. The decoding scheme in the RF transceiver can tolerate up to ±22% clock frequency variation.