Person: López Martín, Antonio
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López Martín
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Antonio
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0000-0001-7629-0305
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Publication Open Access Energy harvesting approaches in IoT scenarios with very low ambient energy(European Association for the Development of Renewable Energy, Environment and Power Quality (EA4EPQ), 2019) López Martín, Antonio; Algueta-Miguel, Jose M.; Matías Maestro, Ignacio; Institute of Smart Cities - ISCThe feasibility of multi-source energy harvesting in Internet of Things (IoT) scenarios with low and intermittent ambient energy is addressed. As a relevant case study, application to a smart cargo container system is analysed. The most relevant features of the main energy sources available in this target application are identified, and various transducers adapted to such sources are evaluated. Measurement results indicate that combined piezoelectric and thermoelectric generation inside cargo containers can significantly extend the battery lifetime of IoT end nodes embedded in such containers.Publication Open Access Analog lock-in amplifier design using subsampling for accuracy enhancement in GMI sensor applications(MDPI, 2023) Algueta-Miguel, Jose M.; Beato López, Juan Jesús; López Martín, Antonio; Ciencias; Zientziak; Institute of Smart Cities - ISC; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PJUPNA2005A frequency downscaling technique for enhancing the accuracy of analog lock-in amplifier (LIA) architectures in giant magneto-impedance (GMI) sensor applications is presented in this paper. As a proof of concept, the proposed method is applied to two different LIA topologies using, respectively, analog and switching-based multiplication for phase-sensitive detection. Specifically, the operation frequency of both the input and the reference signals of the phase-sensitive detector (PSD) block of the LIA is reduced through a subsampling process using sample-and-hold (SH) circuits. A frequency downscaling from 200 kHz, which is the optimal operating frequency of the employed GMI sensor, to 1 kHz has been performed. In this way, the proposed technique exploits the inherent advantages of analog signal multiplication at low frequencies, while the principle of operation of the PSD remains unaltered. The circuits were assembled using discrete components, and the frequency downscaling proposal was experimentally validated by comparing the measurement accuracy with the equivalent conventional circuits. The experimental results revealed that the error in the signal magnitude measurements was reduced by a factor of 8 in the case of the analog multipliers and by a factor of 21 when a PSD based on switched multipliers was used. The error in-phase detection using a two-phase LIA was also reduced by more than 25%.Publication Open Access Sensing in coin discriminators(IEEE, 2007) Carlosena García, Alfonso; López Martín, Antonio; Arizti, Fernando; Martínez de Guereñu, Ane; Pina Insausti, José L.; García Sayés, Miguel; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta ElektronikoaThis paper describes the technologies used in coin discriminator devices, stressing the improvements and novel mechanisms introduced by the authors in the past few years as a result of the cooperation with one leading company in the vending sector. Emphasis is put on how low-cost sensors are used to characterize coins (or tokens) and discriminate them from their counterfeits.Publication Open Access Enhanced single-stage folded cascode OTA suitable for large capacitive loads(IEEE, 2018) López Martín, Antonio; Garde Luque, María Pilar; Algueta-Miguel, Jose M.; Cruz Blas, Carlos Aristóteles de la; Carvajal, Ramón G.; Ramírez-Angulo, Jaime; Institute of Smart Cities - ISCAn enhanced single-stage folded cascode operational transconductance amplifier able to drive large capacitive loads is presented. Circuits that adaptively bias the input differential pair and the current folding stage are employed, which provide class AB operation with dynamic current boosting and increased gainbandwidth (GBW) product. Measurement results of a test chip prototype fabricated in a 0.5-µm CMOS process show an increase in slew rate and GBW by a factor of 30 and 15, respectively, versus the class A version using the same supply voltage and bias currents. Overhead in other performance metrics is small.Publication Open Access Two-stage OTA with all subthreshold MOSFETs and optimum GBW to DC-current ratio(IEEE, 2022) Beloso Legarra, Javier; Grasso, A.; López Martín, Antonio; Palumbo, Gaetano; Pennisi, Salvatore; Institute of Smart Cities - ISCAn approach for the design of two-stage classAB OTAs with sub-1µA current consumption is proposed and demonstrated. The approach employs MOS transistors operating in subthreshold and allows maximum gain-bandwidth product (GBW) to be achieved for a given DC current budget, by setting optimum distribution of DC currents in the two amplifier stages. Following this strategy, a class AB OTA was designed in a standard 0.5-µm CMOS technology supplied from 1.6-V and experimentally tested. Measured GBW was 307 kHz with 980-nA DC current consumption while driving an output capacitance of 40 pF with an average slew rate of 96 V/msPublication Open Access Energy-efficient amplifiers based on quasi-floating gate techniques(MDPI, 2021) López Martín, Antonio; Garde Luque, María Pilar; Algueta-Miguel, Jose M.; Beloso Legarra, Javier; González Carvajal, Ramón; Ramírez-Angulo, Jaime; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de ComunicaciónEnergy efficiency is a key requirement in the design of amplifiers for modern wireless applications. The use of quasi-floating gate (QFG) transistors is a very convenient approach to achieve such energy efficiency. We illustrate different QFG circuit design techniques aimed to implement low-voltage energy-efficient class AB amplifiers. A new super class AB QFG amplifier is presented as a design example including some of the techniques described. The amplifier has been fabricated in a 130 nm CMOS test chip prototype. Measurement results confirm that low-voltage ultra low power amplifiers can be designed preserving at the same time excellent small-signal and large-signal performance.Publication Open Access Fault detection of planetary gears based on signal space constellations(MDPI, 2022) Martincorena Arraiza, Maite; Cruz Blas, Carlos Aristóteles de la; López Martín, Antonio; Molina Vicuña, Cristian; Matías Maestro, Ignacio; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de ComunicaciónA new method to process the vibration signal acquired by an accelerometer placed in a planetary gearbox housing is proposed, which is useful to detect potential faults. The method is based on the phenomenological model and consists of the projection of the healthy vibration signals onto an orthonormal basis. Low pass components representation and Gram–Schmidt’s method are conveniently used to obtain such a basis. Thus, the measured signals can be represented by a set of scalars that provide information on the gear state. If these scalars are within a predefined range, then the gear can be diagnosed as correct; in the opposite case, it will require further evaluation. The method is validated using measured vibration signals obtained from a laboratory test bench.Publication Open Access Micropower class AB low-pass analog filter based on the super-source follower(IEEE, 2022) Martincorena Arraiza, Maite; Cruz Blas, Carlos Aristóteles de la; López Martín, Antonio; Carlosena García, Alfonso; Institute of Smart Cities - ISCAn improved class AB version of the super source follower is used to implement a compact and power-efficient second order analog low-pass filter. The proposed circuit achieves a 41% power reduction as well as an improvement in linearity and pass band gain with respect to its class A counterpart. Measurement results of a test chip prototype fabricated in a 180 nm CMOS technology show a power consumption ranging from 50.3 μW to 85.27 μW for cutoff frequencies from 600 kHz to 890 kHz, with a supply voltage of ±0.75 V. A third order intermodulation distortion of −35.34 dB (for an input signal of 0.4 mV pp and 350 kHz) and a THD of −69.7 dB (for an input signal of 0.4 mV pp and 100 kHz) are measured, which results in an improvement with respect to the conventional class A version of 13.98 dB and 43.6 dB, respectively. The silicon area is 0.0592 mm 2 (using external capacitors).Publication Open Access Design of low-cost smart accelerometers(Universitat Politècnica de Catalunya, 2005) Carlosena García, Alfonso; López Martín, Antonio; Massarotto, Marco; Cruz Blas, Carlos Aristóteles de la; Lecumberri Villamediana, Pablo; Gómez Fernández, Marisol; Pintor Borobia, Jesús María; Gárriz Sanz, Sergio; Ingeniería Eléctrica y Electrónica; Matemáticas; Ingeniería Mecánica, Energética y de Materiales; Ingeniaritza Elektrikoa eta Elektronikoa; Matematika; Mekanika, Energetika eta Materialen IngeniaritzaThe goal of this project is to design a low-cost smart accelerometer, making use of a piezoelectric element as basic sensing material, and adding a mixed-mode conditioning circuit.Publication Open Access Wide-swing class AB regulated cascode current mirror(IEEE, 2020) Garde Luque, María Pilar; López Martín, Antonio; Cruz Blas, Carlos Aristóteles de la; Carvajal, Ramón G.; Ramírez-Angulo, Jaime; Institute of Smart Cities - ISCA micropower regulated cascode CMOS current mirror is presented, combining floating gate and quasi floating gate MOS transistors to achieve both wide swing and class AB operation, respectively. Measurement results for a 0.5 μm CMOS test chip prototype are included, showing that the current mirror can provide a THD at 100 kHz of -44 dB for a supply voltage of ±0.75 V and input current amplitudes 20 times larger than the bias current.