Rezola-Garciandia, A. (Ainhoa)
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- A 22-m operation range semi-passive UHF RFID sensor tag with flexible thermoelectric energy harvester.(IEEE, 2022-10) Solar-Ruiz, H. (Hector); Del-Rio-Orduña, D. (David); Berenguer-Pérez, R.J. (Roque José); Beriain, A. (Andoni); Rezola-Garciandia, A. (Ainhoa)This article presents a wireless temperature sensor tag able to work in both fully passive mode and in semi-passive mode when assisted by a flexible thermoelectric generator (TEG). The sensor tag consists of an EPC C1G2/ISO 18000-6C ultrahigh-frequency (UHF) radio frequency identification (RFID) integrated circuit (IC) connected to a low-power microcontroller unit (MCU) that samples and collects the temperature from a digital temperature sensor. With a temperature gradient as low as 2.5 degrees C, the test results show that the TEG provides an output power of 400 mu W with an output voltage of 40 mV. By means of an up-converter in order to boost the TEG output voltage, this harvester supplies the power required to the sensor tag for a 2-conv/s data rate in semi-passive mode. Moreover, when the tag operates in semi-passive mode, a communication range of 22.2 m is measured for a 2-W effective radiated power (ERP) reader. To the best of our knowledge, the proposed TEG-assisted sensor tag shows the longest communication range and the only one that provides stable external power at low-temperature gradients. The measured performance and the chosen architecture allow using the wireless sensor in multiple industrial or biomedical applications
- A high accuracy 3.1V voltage limiter for enabling high performance RFID sensor applications.(IEEE, 2019) Solar-Ruiz, H. (Hector); Del-Rio-Orduña, D. (David); Berenguer-Pérez, R.J. (Roque José); Beriain, A. (Andoni); Gurutzeaga-Zubillaga, I. (Iñaki); Rezola-Garciandia, A. (Ainhoa)This paper presents a low power voltage limiter design that avoids possible damages in the analog front-end of a RFID sensor due to voltage surges whenever the tag gets close to the reader. The proposed voltage limiter design takes advantage of the implemented bandgap reference block in order to provide a highly accurate limiting voltage in spite of temperature variation and process dispersion. The measured limiting voltage is 3.1V while showing a low current consumption of 100nA when the reader and the tag are far away, so that the sensitivity of the tag is not impacted due to an undesired consumption in the voltage limiter. The circuit is implemented in a low cost 180nm CMOS technology.
- A new practical approach for a basic electrical instrumentation lab to enhance student engagement and performance(Instituto de Óptica "Daza de Valdes", Instituto de Relaciones Internacionales "Daza de Valdes", 2024) Pérez, N. (Noemí); Beriain, A. (Andoni); Solar, H. (Hector); Rezola-Garciandia, A. (Ainhoa)Basic energy and electricity concepts are often misunderstood by first-year engineering students. One of the main reasons for this is that these concepts are perceived as abstract, making it challenging for students to relate them to real-life situations. Experimental laboratories are designed to help students delve deeper into these concepts. However, the demand for more visual aids by students, coupled with their limited ability to grasp complex ideas, often leads to the perception that some labs are outdated and reinforces misconceptions. To address this issue, this article introduces a novel laboratory workbench and methodology aimed at enhancing basic electrical energy and instrumentation laboratory sessions. The approach utilizes a more visual and interactive platform that enables students to connect electrical concepts with real-life elements. Prior to attending the class, students watch instructional videos that demonstrate the practical procedures, following the Flipped Learning strategy. The results of this study reveal that students felt more confident during the laboratory sessions and exhibited a more active attitude, actively asking questions and defending their viewpoints. Professors also observed that time was utilized more effectively, allowing for a better understanding of topics and clarification of confusing content. Overall, the proposed lab sessions significantly improve the learning experience of first-year Physics students and foster their autonomy in learning.
- SDR-based monostatic Chipless RFID Reader with Vector Background Subtraction Capabilities(IEEE, 2023-11) Del-Rio-Orduña, D. (David); Villa-González, F. (Fátima); Bhattcharyya, R. (Rahul); Rezola-Garciandia, A. (Ainhoa); Valderas Gazquez, D.(Daniel)This article presents a high-performance frequency-domain chipless RFID reader with vector background subtraction capabilities, implemented in a software-defined radio (SDR) for the first time. The proposed reader is low-cost, compact size, and versatile. It is implemented in a USRP N210 paired to a modified CBX-40 daughterboard, enabling magnitude and phase data acquisition in a monostatic (one antenna) set up. The reader can perform a vector background subtraction operation between two complex measurements (with and without a chipless tag) to suppress the self-interference (SI) that hinders the response of the tag and provide 40 dB of dynamic range. To demonstrate the performance of the reader, the spectral signatures of three frequency-coded (FC) tags with four resonant frequencies are captured over the 1.5-4-GHz band scanned with 10-MHz resolution in 251 ms, obtaining comparable measurements to those of an expensive laboratory vector network analyzer (VNA) from 20 to 40 cm. The detected resonant frequency offset between both devices is Delta f(r) <= 4.18% . It is also demonstrated that the proposed reader can track a resonant frequency shift and therefore be used in real-time sensing applications.
- Built-in-self-calibration for I/Q imbalance in wideband millimeter-wave gigabit transmitters.(IEEE, 2017-11) Del-Rio-Orduña, D. (David); Berenguer-Pérez, R.J. (Roque José); Gurutzeaga-Zubillaga, I. (Iñaki); Velez-Isasmendi, I. (Igone); Rezola-Garciandia, A. (Ainhoa); Sevillano Berasategui, J. F. (Juan Francisco)This paper addresses the estimation and compensation of I/Q imbalance, one of the most prominent impairments found in wideband zero-intermediate frequency transceivers (TRxs). The I/Q imbalance encountered in this kind of TRx comprises not only frequency-selective gain and phase imbalance but also delay imbalance. Unless appropriate compensation is applied, the I/Q imbalance significantly degrades the performance of a communication system. This paper presents a novel compensation technique for transmitter I/Q imbalance based on built-in-self-calibration, a low cost and robust compensation technique that enables manufacturing as well as in-field calibration with low computational complexity. The method's performance is evaluated in a TRx with 64-quadratic-amplitude modulation and 2 GHz of bandwidth implemented with real hardware. The measurements show that the proposed technique achieves an image rejection ratio greater than 35 dB in the entire 2 GHz bandwidth and an error vector magnitude lower than 3%.
- A 15-21 GHz I/Q upconverter with an on-chip linearization circuit for 10 Gbps mm-wave tinks.(IEEE, 2017-05) Del-Rio-Orduña, D. (David); Berenguer-Pérez, R.J. (Roque José); Puyal, V. (Vincent); Gurutzeaga-Zubillaga, I. (Iñaki); Velez-Isasmendi, I. (Igone); Rezola-Garciandia, A. (Ainhoa); Sevillano Berasategui, J. F. (Juan Francisco); González-Jiménez, J.L. (José Luís)This letter presents a 15-21 GHz I/ Q upconverter, based on two Gilbert-cell mixers with an on-chip wideband linearization loop that extends the linear region and allows power efficient operation at backoff power levels. A quadrature LO signal is generated using an integrated two-stage polyphase filter. Measurements show a conversion gain of -5.5 dB, an output 1-dB compression point of 0 dBm, and an image suppression of 40 dB over the 6-GHz output bandwidth. An error vector magnitude of 3.5% is obtained for a 10-Gb/s 64-QAM signal with a bandwidth of 2 GHz. The circuit is integrated in a 55-nm BiCMOS process and occupies 1.07 mm(2) . The dc power consumption is 61 mW.
- Temperature-dependent I/Q imbalance compensation in ultra-wideband millimeter-wave multi-gigabit transmitters(IEEE, 2020-01) Del-Rio-Orduña, D. (David); Berenguer-Pérez, R.J. (Roque José); Martín, B. (Belén); Gurutzeaga-Zubillaga, I. (Iñaki); Velez-Isasmendi, I. (Igone); Rezola-Garciandia, A. (Ainhoa); Sevillano Berasategui, J. F. (Juan Francisco)Changes in ambient temperature or chip temperature result in variations in the in-phase and quadrature (I/Q) gain and phase imbalance. As a consequence, the overall system performance can be seriously degraded, especially in wideband multi-Gb/s systems, where the I/Q imbalance is highly selective in frequency. Unless appropriately considered, temperature drifts can decrease the image rejection ratio (IRR) of the transmitter. This article presents a novel compensation method for temperature-dependent transmitter I/Q imbalance over the entire temperature range. It consists of a simple predistortion technique that, based on a few factory characterizations of gain and phase imbalance, is able to estimate and correct the I/Q imbalance at any temperature, without interrupting the normal functionality of the system. The proposed method is assessed in a 2-GHz, 64-QAM transceiver implemented with real hardware. The measurements show that the proposed approach is able to keep the IRR greater than 35 dB in the entire bandwidth and an error vector magnitude (EVM) lower than 3 over a temperature range of 70 C.
- SDR-Based monostatic chipless RFID reader with vector backgroud substration capabilities(IEEE, 2023) Del-Rio-Orduña, D. (David); Bhattacharyya, R. (RahuL); Villa-González, F. (Fátima); Rezola-Garciandia, A. (Ainhoa); Valderas Gazquez, D.(Daniel)This article presents a high-performance frequency-domain chipless RFID reader with vector background subtraction capabilities, implemented in a software-defined radio (SDR) for the first time. The proposed reader is low-cost, compact size, and versatile. It is implemented in a USRP N210 paired to a modified CBX-40 daughterboard, enabling magnitude and phase data acquisition in a monostatic (one antenna) set up. The reader can perform a vector background subtraction operation between two complex measurements (with and without a chipless tag) to suppress the self-interference (SI) that hinders the response of the tag and provide 40 dB of dynamic range. To demonstrate the performance of the reader, the spectral signatures of three frequency-coded (FC) tags with four resonant frequencies are captured over the 1.5-4-GHz band scanned with 10-MHz resolution in 251 ms, obtaining comparable measurements to those of an expensive laboratory vector network analyzer (VNA) from 20 to 40 cm. The detected resonant frequency offset between both devices is Delta f(r) <= 4.18% . It is also demonstrated that the proposed reader can track a resonant frequency shift and therefore be used in real-time sensing applications.
- A wideband and high-linearity E-band transmitter integrated in a 55-nm SiGe technology for backhaul point-to-point 10-Gb/s links(IEEE, 2017-08) Saavedra, C.E. (Carlos E.); Del-Rio-Orduña, D. (David); Berenguer-Pérez, R.J. (Roque José); Tamir, N. (Nataly); Dehos, C. (Cédric); Gurutzeaga-Zubillaga, I. (Iñaki); Velez-Isasmendi, I. (Igone); Rezola-Garciandia, A. (Ainhoa); Sevillano Berasategui, J. F. (Juan Francisco); Siligaris, A. (Alexandre); Gunnarsson, S. E. (Sten E.); González-Jiménez, J.L. (José Luís)This paper presents the design of a wideband and high-linearity E-band transmitter integrated in a 55-nm SiGe BiCMOS technology. It consists of a double-balanced bipolar ring mixer which upconverts a 16-21-GHz IF signal to the 71-76- and 81-86-GHz bands by the use of a 55/65-GHz local oscillator signal, followed by a broadband power amplifier which employs 2-way output power combining using an integrated low-loss balun transformer. The transmitter exhibits an average conversion gain of 24 dB and 22 dB at the 71-76- and 81-86-GHz bands, respectively, with an output 1-dB compression point greater than 14 and 11.5 dBm at each band. A maximum output power of 16.8 dBm is measured at 71 GHz. The dc power consumption is 575 mW. The presented transmitter is used to demonstrate the transmission of a 10.12-Gb/s 64 quadrature amplitude modulated signal with a spectral efficiency of 5.06 bit/s/Hz, which makes it suitable for use in future highcapacity backhaul and fronthaul point-to-point links.
- An enhanced methodology to improve a basic electrical and instrumentation laboratory session(Institute of Electrical and Electronics Engineers, 2020) Pérez, N. (Noemí); Rezola-Garciandia, A. (Ainhoa); Caballero, D. (Damian); Solar, H. (Hector); Macayo, J. (José)First year students have shown difficulties understanding basic electrical, instrumentation and electronic concepts. In this context, traditional laboratory work is considered as old-fashioned and not very useful for them. In addition, an important part of the time in the lab is spent giving explanations about the basic functioning of measurement instruments and not actually working on the lab experiments. Also, in laboratories with many students the waiting time for the help of the professor is often long and most of the questions are repeated group by group and year by year. To overcome all these issues, we present an improvement of a traditional instrumentation lab practice with an interactive and visual platform that allows students to associate electrical concepts with real day life elements. Self-explaining videos of all the instrumentation elements aid students to be better prepared for practical work before class and to get an immediate on demand help while they are in the lab. This way, the time they are waiting for help is reduced, making the most of the lab practices.