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.

[1]  Shoushun Chen,et al.  Live demonstration: A FSK-OOK ultra wideband impulse radio system with spontaneous clock and data recovery , 2012, 2012 IEEE International Symposium on Circuits and Systems.

[2]  Alyssa B. Apsel,et al.  An Ultralow-Power Dual-Band UWB Impulse Radio , 2010, IEEE Transactions on Circuits and Systems II: Express Briefs.

[3]  Jorge R. Fernandes,et al.  An Ultra-Wideband Impulse-Radio Transceiver Chipset Using Synchronized-OOK Modulation , 2011, IEEE Journal of Solid-State Circuits.

[4]  Yong Ping Xu,et al.  A 1-V 32-µW 13-bit CMOS Sigma-Delta A/D converter for biomedical applications , 2009, 2009 IEEE 8th International Conference on ASIC.

[5]  Chang-Jun Ahn,et al.  Sorter-Based Arithmetic Circuits for Sigma-Delta Domain Signal Processing—Part I: Addition, Approximate Transcendental Functions, and Log-Domain Operations , 2012, IEEE Transactions on Circuits and Systems I: Regular Papers.

[6]  Mohsen Mollazadeh,et al.  A VLSI Neural Monitoring System With Ultra-Wideband Telemetry for Awake Behaving Subjects , 2011, IEEE Transactions on Biomedical Circuits and Systems.

[7]  Jordi Parramon,et al.  A Low-Power Configurable Neural Recording System for Epileptic Seizure Detection , 2013, IEEE Transactions on Biomedical Circuits and Systems.

[8]  Eugenio Culurciello,et al.  A non-coherent FSK-OOK UWB impulse radio transmitter for clock-less synchronization , 2011, 2011 IEEE International Symposium of Circuits and Systems (ISCAS).

[9]  Wei Tang,et al.  Asynchronous communication for wireless sensors using ultra wideband impulse radio , 2015, 2015 IEEE 58th International Midwest Symposium on Circuits and Systems (MWSCAS).

[10]  Naveen Verma,et al.  A Micro-Power EEG Acquisition SoC With Integrated Feature Extraction Processor for a Chronic Seizure Detection System , 2010, IEEE Journal of Solid-State Circuits.

[11]  M. Høvin,et al.  Delta-sigma modulators using frequency-modulated intermediate values , 1997, IEEE J. Solid State Circuits.

[12]  Luis Hernández,et al.  Analytical Evaluation of VCO-ADC Quantization Noise Spectrum Using Pulse Frequency Modulation , 2015, IEEE Signal Processing Letters.

[13]  Christian Bachmann,et al.  Low-power wireless sensor nodes for ubiquitous long-term biomedical signal monitoring , 2012, IEEE Communications Magazine.