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

Abstract

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.