Biomedical sensor interface for PLI cancellation

A Mixed-signal bio-potential signal interface is presented. It uses a feedback loop that acts like an adaptive notch filter to increase system immunity to power line interference. 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 implementation area compared to previous work that uses mixed signal feedback loop for power line interference cancellation. The system is implemented using 0.13μm CMOS process and consumes 7.5 μA from 2.5V supply. The system rejects up to 2V amplitude of PLI which reduces the required ADC resolution from 12 bits to 7 bits.