Wireless Voltage Regulation for Passive Transponders Using an IF to Communicate

Michel Declercq, Catherine Dehollain, Nicolas Pillin
2010
Article

Résumé

This paper presents a novel architecture for wireless communication systems made up of a base station and a remotely powered transponder. The architecture enables the base station to perform wireless voltage regulation (WVR) of the rectifier's output voltage in the transponder. This new regulation technique can be embedded in any system, provided that the passive transponder uses an IF to transmit data to the base station. The technique relies on a large scale, wireless feedback loop that includes the base station, and the transponder. The overall power efficiency of the system is improved compared to conventional voltage regulation technique. A small-signal model is derived to gain some insight on the dynamics and on the stability of the feedback loop. Measurements were made on an actual system operating in far field at 866.6 MHz. They demonstrate the efficiency improvement related to the use of WVR. The validity of the small-signal model is discussed according to the measurement results. © 2010 IEEE.

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https://infoscience.epfl.ch/record/148938?ln=fr

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Michel Declercq, Catherine Dehollain, Nicolas Pillin
2010
Article

Résumé

Official source

https://infoscience.epfl.ch/record/148938?ln=fr

À propos de ce résultat

Concepts associés (14)

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A System for Wireless Power Transfer of Micro-Systems In-Vivo Implantable in Freely Moving Animals

Gilbert Didier Francis Conus, Catherine Dehollain, Basile Kawkabani, Enver Gürhan Kilinç, Franco Maloberti, Chloé Weber

A system for wireless power transfer of micro-systems in-vivo implantable in small animals is presented. The described solution uses a servo-controlled transmitter moved under the animal moving space. The solution minimizes the power irradiation while enabling animal speeds up to 30 cm/s. An x-y movable magnetic coil transmits the required power with a level able to keep constant the received energy. A permanent magnet on board of the implantable micro-system and an array of magnetic sensors form a coil tracking system capable of an alignment accuracy as good as 1 cm. The power is transferred over the optimized remote powering link at 13.56 MHz. The received ac signal is converted to dc voltage with a passive full-wave integrated rectifier and the voltage regulator supplies 1.8 V for the implantable sensor system. Experimental measurement on a complete prototype verifies the system performance.

Institute of Electrical and Electronics Engineers2014

Chargement

Efficient systems for determining the precise position and orientation of airborne sensors will have a great impact in different remote sensing activities, with consequences in their productivity and therefore substantially increasing their cost effectiveness. In the scope of national and international projects, the authors have developed and tested an airborne system built with multiple GPS receivers and a low cost inertial unit. The methodology is based on the integrated processing of raw inertial measurements and GPS data collected from two receivers on board the aircraft and one, or possibly more, reference stations. The algorithm for processing GPS and IMU (Inertial Measurement Unit) raw data was implemented in an integrated feedback loop. The position determination is based on DGPS with OTF ambiguity fixing, using on-line processed inertial data to validate and increase position reliability, especially during GPS outages and when the aircraft is far away from the nearest GPS reference station. For the attitude angles, the IMU raw data is processed using absolute GPS position/velocity updates for continuous alignment. Also, by processing L1 and L2 carrier phase measurements in differential mode between two GPS antennas on the aircraft (without resorting to ground reference station data), a partial estimate of the aircraft attitude is obtained. This is critical to align the low cost inertial platform in heading either when the aircraft is stopped or in stable flight. The inertial system also provides high rate (DGPS filtered) position and velocity estimates that can be valuable during GPS signal outages and for the robustness of the ambiguity fixing procedures. By using the proposed methodology it was possible to explore the entire potential of a low cost GPS/IMU system. The position and attitude values are obtained from all the measurements through an Extended Kalman Filter. Decimeter accuracy was achieved for the positions, while the estimated accuracy for the aircraft orientation is 0.01º for roll and pitch and 0.05º for heading (maximum values). The basic idea was to develop a low cost system that can supply position and attitude with a level of accuracy and reliability similar to more expensive systems, such us gimbaled and ring laser gyro based inertial systems. The final tests of this GPS/IMU system took place during this summer. The inclusion of a radio link between a reference station and the aircraft enabled the system to operate in real time. It proved to be successful in navigating the aircraft during all flight phases, including runway approach and landing. Furthermore, aerial photographs were taken in order to have an independent evaluation of the system accuracy. Results from the airborne campaigns and the performance of this system are presented. Its potential for different applications is discussed.

1999

Chargement

Efficiency enhancement and frequency-tunable capability in linear CMOS RF power amplifiers for wireless applications

Paulo Augusto Dal Fabbro

This research work deals with the design of linear CMOS RF power amplifiers. Two important aspects are treated: efficiency enhancement and frequency-tunable capability. For this purpose, two different integrated circuits were realized in a 0.11 µm technology, each one addressing a different aspect. With respect to efficiency enhancement, a dynamic supply RF power amplifier was realized. The circuit was designed for an operating frequency of 5.2 GHz, but measurements were also performed at 2.4 GHz. The integrated circuit includes a class A amplifier and a high-efficiency, switched-mode modulator. It occupies an area of 1.35 mm2. Two-tone measurement results at 2.4 and 5.2 GHz showed that the system can deliver over 16 dBm (40 mW) linear output power with efficiencies of 22.7% and 12.6%, respectively. Compared to a constant 2.5 V supply operation, the power amplifier operating with the dynamic supply delivers higher linear output power. Moreover, a relative efficiency improvement of a factor of 2.3 at 2.4 GHz and of a factor of 1.6 at 5.2 GHz at low output power levels is achieved. OFDM measurements at 2.4 GHz demonstrated that for an EVM lower than 3% and for an equal output power of 11 dBm (12.6 mW), the absolute improvement in efficiency is over 3.2%. In this work we also propose a tunable impedance matching network for use in multiband RF power amplifiers. This novel network is based on coupled inductors. A frequency-tunable RF power amplifier using this network was designed for operation at 3.7 and 5.2 GHz. Simulation results for the complete system integrated in a CMOS technology showed good results. However, the frequency-tunable behavior could not be observed in the characterization of the integrated circuit because of the low coupling factor of the integrated coupled inductors. A hybrid implementation using the integrated CMOS power amplifier, a discrete commercial RF transformer and a discrete bipolar transistor to control the current in the secondary winding of the transformer was carried out. The circuit was designed for operation at 200 and 300 MHz. The measurements have shown that at 200 MHz a relative improvement in efficiency of a factor of 1.4 was achieved. Moreover, less distortion was generated with the proposed tunable output matching network. The hybrid implementation allowed us to demonstrate the feasibility of the frequency-tunable RF power amplifier based on coupled inductors.

EPFL2009

Chargement

Efficiency enhancement and frequency-tunable capability in linear CMOS RF power amplifiers for wireless applications

Paulo Augusto Dal Fabbro

EPFL2009

1999