Récepteur Sans-Fil à Basse Consommation et à Modulation Mixte FSK-ASK pour les Dispositifs Médicaux

RÉSUMÉ Les émetteurs-récepteurs radiofréquences (RF) offrent le lien de communications le plus commun afin de mettre au point des dispositifs médicaux implantables dédiés aux interfaces homme-machines. La surveillance en continu des paramètres biologiques des patients nécessite un module de communication sans-fil capable de garantir un échange de données rapide, en temps réel, à faible puissance tout en étant implémenté dans un espace physique réduit. La consommation de puissance des dispositifs implantables joue un rôle important dans les durées de vie des batteries qui nécessitent une chirurgie pour leur remplacement, à moins qu’une technique de transfert de puissance sans-fil soit utilisée pour recharger la batterie ou alimenter l’implant a travers les tissus humains. Dans ce projet, nous avons conçu, implémenté et testé un récepteur RF à faible puissance et haut-débit de données opérant entre 902 et 928 MHz qui est la bande industrielle-scientifiquemédicale (Industrial, Scientific and Medical) d’Amérique du Nord. Ce récepteur fait partie d’un système de communication bidirectionnel dédié à l’interface sans-fil des dispositifs électroniques implantables et bénéficie d’une nouvelle technique de conversion de modulation par déplacement de fréquence (FSK) en Modulation par déplacement d’amplitude (ASK). Toutes les phases de conception et d’implémentation de la topologie adoptée pour les récepteurs RF sont survolées et discutées dans cette thèse. Les différents étages de circuits sont conçus selon une étude analytique fondée de la modulation FSK et ASK utilisées, ce qui permettra une amélioration des performances notamment le débit de transmission des données et la consommation de puissance. Tous les circuits sont réalisés de façon à ce que la consommation totale et la surface de silicium à réserver soient le minimum possible. Un oscillateur avec verrouillage par injection (Injection-Looked Oscillator - ILO) de faible puissance est réalisé pour assurer la conversion des signaux ASK en FSK. Une combinaison des avantages des deux architectures de modulation d’amplitude et de fréquence, pour les circuits d’émetteurrécepteur sans fil, a été réalisé avec le système proposé. Un module incluant un récepteur de réveil (Wake up) est ajouté afin d’optimiser la consommation totale du circuit en mettant tous les blocs à l’arrêt. Nous avons réalisé un récepteur de réveil RF compact et à faible coût, permettant de très faible niveaux de consommation d’énergie, une bonne sensibilité et une meilleure tolérance aux interférences. Le design est basé sur une topologie homodyne à détection d’enveloppe permettant une transposition directe du signal RF modulé en amplitude en un signal en bande de base. Cette architecture nécessite une architecture peu encombrante à intégrer qui élimine le problème des fréquences image pour la même topologie avec une modulation de fréquence.---------- ABSTRACT ISM band transceiver using a wake-up bloc for wireless body area networks (WBANs) wearable and implantable medical devices is proposed. The system achieves exceptionally low-power consumption and allows a high-data rate by combining the advantages of Frequency-Shift-Keying (FSK) and Amplitude-Shift- Keying (ASK) modulation techniques. The transceiver employs FSK modulation at a data rate of 8 Mbit/s to establish RF link among the medical device and a control unit. Transmitter (Tx) includes a new efficient FSK modulation scheme which offer up to 20 Mb/s of data-rate and dissipates around 0.084 nJ/b. The design of the proposed oscillator achieves variable frequency from 300 kHz to 8 MHz by adjusting the transistors geometry, the on-chip control signal and the tuning capacitors. In the transmitter path, the high-quality LOs Inand Quadrature-phase (I and Q) outputs are produced using a very low-power fully integrated integer-N frequency synthesizer. The architecture of the receiver is inspired from the super-regenerative receiver (SRR) topology which can be used to design a transceiver that is suitable for ASK modulation. In fact, this architecture is based mainly on envelope detection scheme which remove the need to process the carrier phase to reduce the complexity of integrated design. It has been shown too, that the envelope detection scheme is more robust to phase noise than the coherent scheme. The integrated receiver uses on a new FSK-to-ASK conversion technique. The conversion feature that we adopt in the main receiver design is based on the fact that the incident frequency of converter could be differentiated by the amplitude of output signal, which conducts to the frequency-to-amplitude conversion. Thanks to the injection locking oscillator (ILO). the new design of converter is located between the LNA as first part and the envelope detector as second part to benefit from the injection-locking isolation. On-Off-keying (OOK) fully passive wake-up circuit (WuRx) with energy harvesting from Radio Frequency (RF) link is used to optimize the power issipation of the RF transceiver in order to meet the low power requirement. The WuRx operates at the ISM 902–928 MHz. A high efficiency differential rectifier behaves as voltage multiplier. It generates the envelope of the input signal and provides the supply voltage for the rest of blocks including a low-power comparator and reference generators

Reconfigurable self-calibrated multi-sensing RFID-based platform

This paper concerns an RFID tag platform using an integrated temperature sensor and external pressure sensor targeted for the Electronics Product Code (EPC) Gen-2 standard operating in the 902-928 MHz ISM band. The developed system is part of a low-cost wireless sensors network node. This work demonstrates the study, development, and troubleshooting of battery-assisted sensing platform compliant to the RFID standard electronic product code Gen-2. Two main scenarios are tested to connect the sensorspassive and semi-passive tags. The two architectures allow collecting data based on either the RFID reader command or a signal processing program to save the sensing data using the integrated circuit memory. Temperature and pressure measurements are performed based on the integrated and external sensors combined in the RFID circuit board. Besides the fully integrated temperature sensor with a sensing precision of 0.5 C over the target temperature range, external pressure sensor is connected to provide a flexible way for additional sensors interfacing. Sensor are connected to a single system as the design is intended for a reconfigurable self-calibrated multi-sensing platform. The proposed sensing tags are fully verified through measurements.Scopu

EPC Gen-2 UHF RFID tags with low-power CMOS temperature sensor suitable for gas applications

This paper presents a passive RFID tag with an embedded temperature sensor intended for the EPC Gen-2 protocol operating in the 902-928 MHz ISM band. The design is implemented as a node of a low cost temperature sensors network. The system is powered by a remote power through the RF energy received from the reader in order to create autonomous temperature measurement micro systems. The temperature sensor is based on ring oscillator using CMOS thyristor delay element. The energy recovery and power distribution unit of the RFID tag provides different supply voltages in order to optimize the performance and the power consumption of each building block. Amplitude Shift Keying (ASK) modulation architecture is adopted for Radio Frequency (RF) link which uses an envelope detector and non-coherent demodulation technique. For the temperature sensor, Low power operation is achieved by eliminating the use of power hungry Analog to Digital Converters (ADCs) at the sensor output. The design architecture is fully compliant to the EPC Gen-2 standard. The error in temperature sensing is around-1.8 C/+1 C, with a resolution of 0.3 C. The RFID tag achieves a sensitivity of-11 dBm with an input data rate up to 200 kbps from 1.8V. 0.5Vwas used as supply voltage for the temperature sensor to ensure the low power consumption as well as robustness. The proposed UHF RFID tag is implemented and simulated in 0.18?mCMOS process.Scopu

Gas Identification Using Passive UHF RFID Sensor Platform

The concept of passive Radio Frequency Identification (RFID) sensor tag is introduced to remove the dependency of current RFID platforms on battery life. In this paper, a gas identification system is presented using passive RFID sensor tag along with the processing unit. The RFID system is compliant to Electronics Product Code Generation 2 (EPC-Gen2) protocol in 902-928 MHz ISM band. Whereas the processing unit is implemented and analyzed in software and hardware platforms. The software platform uses MATLAB, whereas a High Level Synthesis (HLS) tool is used to implement the processing unit on a Zynq platform. Moreover, two sets of different gases are used along with Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) based feature reduction approaches to analyze in detail the best feature reduction approach for efficient classification of gas data. It is found that for the first set of gases, 90 % gases are identified using first three principal components, which is 7 % more efficient than LDA. However in terms of hardware overhead, LDA requires 50 % less hardware resources than PCA. The classification results for the second set of gases reveal that 91 % of gas classification is obtained using LDA and first four PCA, while LDA requires 52 % less hardware resources than PCA. The RFID tag used for transmission is implemented in 0.13 µm CMOS process, with simulated average power consumption of 2.6 µW from 1.2 V supply. ThingMagic M6e embedded reader is used for RFID platform implementation. It shows an output power of 31.5 dBm which allows a read range up to 9 meters