Velez-Isasmendi, I. (Igone)
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- 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.
- 5G Performance measurements in mobility for the bus transportation system in an urban environment.(IEEE, 2023-12) Bustamante, P. (Paul); Fernández-Berrueta, N. (Nerea); Velez-Isasmendi, I. (Igone); Figueroa-Lorenzo, S. (Santiago); Arrizabalaga-Juaristi, S. (Saioa)5G is a new technology that can provide more services, due to the improvement in performance, than the current mobile technologies. Because of that, it is selected as a possible technology for automotive transportation systems. Nevertheless, nowadays the 5G technology is in the deployment phase, which could present bugs requiring improvements in the network. Therefore, a tool capable of measuring some of the most relevant features of the 5G, as some of the requirements for the transportation system, is presented. The measurements with the specified tool were carried out in a specific line from the bus company in the San Sebastian city center with the aim of finding out the services that could be improved. Afterward, the results from the different measurements are shown, compared, and discussed. Finally, some conclusions about the obtained results and the services to use the target technology are presented.
- Novel classification method to predict the accuracy of UWB ranging estimates(2024) Ochoa-de-Eribe-Landaberea, A. (Aitor); Zamora-Cardenas, L. (Leticia); Velez-Isasmendi, I. (Igone); Arsuaga, M. (Meritxell); Arrizabalaga-Juaristi, S. (Saioa)Real time location systems (RTLSs) are becoming more relevant in a more data driven economy and society due to their wide range of application cases. When the location of an object needs to be tracked with high accuracy, ultra wideband (UWB) technology is usually the best option. Nevertheless, UWB ranging estimates are not completely immune to some sources of error such as non line of sight (NLOS) or multipath conditions. Thus, this paper proposes a real-time classification model based on machine learning (ML) to predict if received ranging estimates are in line of sight (LOS) or NLOS conditions and discard those in NLOS. However, it is also shown that classifying measurements as LOS or NLOS does not guarantee detecting inaccurate ranging estimates, since LOS measurements can also yield large errors. As an example, the ranging root mean square error (RMSE) of the data labelled as LOS in a UWB based localization system database in the literature is of 0.714 m, significantly higher than the theoretical accuracy of a UWB system. Thus, a novel ML-based classification model is proposed to predict the magnitude of the ranging error. After applying the proposed classification model in the same data, the ranging RMSE of those ranging samples classified as most accurate is of only 0.183 m, significantly lower than the best RMSE we can obtain on the classical LOS/NLOS classification approach.
- 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.