Delta–Sigma Encoder for Low-Power Wireless Bio-Sensors Using Ultrawideband Impulse Radio

This brief presents a systematic method to reduce the power consumption of a wireless sensor node for sensing biomedical signals. The design combines the delta-sigma modulator (DSM), the ultrawideband impulse radio (UWB-IR), and the proposed xnor-delay-based encoder/decoder, which replaces the decimation filter. The encoder and decoder for both the first- and second-order DSMs are presented. The clock synchronization problem is solved by using an asynchronous UWB-IR. The effects of window length, the order of delta-sigma modulation, and the oversampling ratio are studied by simulation using neural and electrocardiography signals. Based on the simulation results, the proposed method can save power by 50% compared to the system with decimation filters, and 53% compared to the system without the proposed encoder.