Iker Mayordomo

Development of a Wireless Power Transmission System for Embedded Passive Sensors Using LF RFID Technology

Wireless power transmission (WPT) can be used to enable full embedding of sensor systems and thus remove the need for wired connections and batteries. In this paper a WPT system based on inductive coupling at 125 kHz is presented. The main design considerations that must be taken into account when designing such a system will be presented. This includes the design of the power transmitter and the power receiver as well as the fabrication of proper antennas. The proposed system architecture has been completely implemented and measurements have been carried out for validation. It is demonstrated that the fabricated system achieves a wireless transmission of 10.4 W at a 5 cm distance with 69 percent efficiency and 7.9 W at 10 cm distance with 30 percent efficiency. In order to facilitate the integration of the wireless system, a new version of the antennas and the PCB have been fabricated. Two different prototypes are built with two different antenna coil thicknesss. The obtained results corroborate the importance of the selected wire resistivity, since 5.9 W and 9.5 W are obtained for 0.5 mm and 1 mm thickness respectively at a 5 cm distance. A first prototype has also been fabricated to prove that the WPT electronics can be successfully embedded into the composite.

High-Resolution ACLR Measurement Architecture for Adaptive Feedforward Amplifiers

One of the most restrictive linearity constraints to RF transmitter nonlinearity is the unwanted emission immediately outside the channel bandwidth, mostly known as adjacent channel leakage ratio (ACLR). In this paper, novel architecture design rules are presented for ACLR-level measurement in feedforward adaptive amplifiers. Both main and distortion signal power levels are obtained without any masquerading effect and with minimum component utilization. A prototype implementation is introduced to validate the proposed design rules, and a commercial spectrum analyzer is used for accuracy checking. Finally, the thermal stability has been tested for the -20degC to 70degC range.

Simulation and measurement of a long-range passive RFID system focused on reader architecture and backscattering communication

With passive tags achieving longer read ranges, the design of a proper long-range RFID reader has become a challenging issue. A complete long-range passive RFID system, focused on the backscattering tag-to-reader communication and the reader architecture, is presented in this paper. Main reader design constraints are discussed. Guidelines to design a PSK backscatter modulator are also given. The system is not only simulated, but also fabricated and measured. Thus, both the designed reader architecture and the simulation tool are validated. A read range of 10.6 m with only an 11deg phase difference has been measured.