ASICs for Bio-medical Wireless Sensor Networks

Abstract

One of the important challenges in designing Bio-medical Wireless Sensor Net-works is to build implantable systems which have high interference immunity, low noise, low-power bio-potential circuits capable of dealing with signals in the mHz to hundreds of Hz range. This thesis investigates a low power interference cancellation bio-medical system with low-power and low noise interface circuitry which can be utilized in body area wireless sensor nodes and networks. Dierent power line cancellation system architectures, including digital and ana-log implementations, are studied. A Mixed-signal bio-potential signal interface system is presented. The system utilizes an analog/mixed feedback loop that acts like an adaptive notch _lter to increase system immunity to power line in-terference at 50/60 Hz. The proposed feedback loop automatically detects the frequency of power line interference without the need for a phase locked loop, it also exploits an optimized technique for frequency generation that minimizes digital system implementation area and complexity compared to previous work that uses mixed signal feedback loop for power line interference cancellation in low power bio-medical systems. System level simulations are done using Matlab. Accurate Verilog-A models for system blocks were used to simulate the whole system, then, the system is implemented on 0.13_m CMOS technology. As a test case, a contaminated ECG signal with power line interference is inserted to the input of the system.