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Aiming to shed light on the operation of fully-digital transmitters, we present the first symbol-rate baseband model that makes explicit the inter-symbol interference introduced by the RF pulse-width modulation (RF-PWM). The proposed model expresses the transmitter output as symbols plus interference, paving the way for the derivation of in-band performance metrics of the communication system. Then, we find an approximation for the error vector magnitude that allows us to evaluate the impact of the oversampling ratio, the statistics of the transmitted symbols and the shaping pulse in the transmitter performance. Another advantage of the model is that simulation times are much shorter since it does not require interpolation to appreciate the PWM distortion. To obtain the model, we first assume a generic expression of the continuous-time signal to be transmitted, in terms of the information symbols and the reconstruction filter. This allows us to express the nonlinear differential equation that models the intrinsic distortion also in terms of the sent symbols. Then, we elaborate on the formulation of the continuous-time RF-PWM distortion to procure an expression of the received signal sampled at symbol rate. The article concludes with a numerical validation of the model, and a simulation of the bit error rate of the system.

This article proposes a new technique to reduce the readout noise in charge-coupled devices (CCDs). The objective is to minimize the common noise between the channels. This noise is either induced by the readout electronics or by the environment, and it could be present in small (single CCD and a few channels) or large systems (dozens of CCDs and hundreds of channels). By interleaving the video signals, we show that it is possible to reduce the readout noise by around 50% without sacrificing output channels at the expense of a moderate increase of the readout time, which is less compared with other techniques. Up until now, similar approaches have used half of the output stages only for noise measurement doubling the total readout time of the sensor. Simulations and experimental results are presented to validate the proposed approach. Moreover, the technique is measured using a Skipper CCD, and its operation is validated together with the ability of the Skipper sensor for nondestructively reading, several times, the same pixel charge. With the combination of both techniques, we achieve deep subelectron readout noise levels (0.1 e−).

A design for an all-digital high-resolution pulse-width modulator (HRPWM) architecture is presented in this work. The architecture is based on a novel digitally controlled delay element that combines two different approaches, achieving a variable time interval up to 54 ps, and adjustable against process, voltage, and temperature (PVT) variations. The proposed system uses several delay elements with a counter-based digital pulse-width modulator (DPWM) in a hybrid configuration, which allows to obtain duty cycles with 18-bit resolution without using a high-frequency internal clock and maintaining a low power dissipation. The HRPWM was implemented in a standard low-cost 130-nm CMOS technology, together with a memory used to store the duty cycles, and a serial communication module. Post layout simulation results show good linearity between the control word and the duty cycle in all the range. The chip can be fine tuned to improve its performance using the calibration capabilities of the architecture. The analysis includes a comparison with another state-of-art HRPWMs showing the advantages of the proposed approach. Fil: Morales, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Chierchie, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Mandolesi, Pablo Sergio. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Paolini, Eduardo Emilio. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina

This article provides a practical design methodology to calculate an optimal filter for noise reduction in the readout of charge‐coupled devices (CCDs) taking into account the charge transfer and feedthroughs due to capacitive coupling in the CCD. A detailed analysis of the dynamics of the video signal and charge transfer is presented, including the circuital modeling of the output stage of the CCD and the dynamics of the electronics in the video chain before the analog‐to‐digital (AD) converter. This model is used to compute an optimal filter that minimizes the variance of the pixel noise and uses the samples of the charge transfer, before the charge is fully settled. This is necessary to enhance the performance of previous results that also use optimal filters but do not use the transition samples, while also reducing the pixel readout time, resulting in faster readouts. As a proof of concept for the optimal filter, we present novel experimental results using a Skipper CCD, which has a floating sense node that allows to measure the charge packet an arbitrary number of times. However, this technique can be applied to any CCD that has a readout system that digitally samples the video signal. Fil: Chierchie, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Fernández Moroni, Guillermo. Fermi National Accelerator Laboratory; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Querejeta Simbeni, Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Stefanazzi, Leandro. Fermi National Accelerator Laboratory; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Paolini, Eduardo Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina Fil: Sofo Haro, Miguel Francisco. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Fermi National Accelerator Laboratory; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Cancelo, Gustavo Indalecio. Fermi National Accelerator Laboratory; Estados Unidos Fil: Estrada, Juan. Fermi National Accelerator Laboratory; Estados Unidos

The skipper CCD is a special type of charge coupled device in which the readout noise can be reduced to sub-electron levels by averaging independent measurements of the same charge. Thus the charge in the pixels can be determined by counting the exact number of electrons. The total readout time is proportional to the number of measurements of the charge in each pixel. For some applications this time may be too long; however, researchers usually are interested only on certain region within the matrix of pixels. In this paper we present the development of a smart skipper readout technique that allows the user to specify regions of interest of the CCD matrix where an arbitrary (high) number of measurements of the same charge can taken to obtain the desired noise level, and far less measurements are performed in those regions that are less interesting to the researcher, therefore reducing the total readout time.

The development of the Skipper-charge-coupled devices (Skipper-CCDs) has been a major technological breakthrough for sensing very weak ionizing particles. The sensor allows to reach the ultimate sensitivity of silicon material as a charge signal sensor by unambiguous determination of the charge signal collected by each cell or pixel, even for single electron–hole pair ionization. Extensive use of the technology was limited by the lack of specific equipment to operate the sensor at the ultimate performance. A simple, single-board Skipper-CCD controller designed by the authors is presented and aimed for the operation of the detector in high sensitivity scientific applications. Our article describes the main components and functionality of the so-called low threshold acquisition controller together with experimental results when connected to a Skipper-CCD sensor. Measurements show unprecedented deep subelectron noise of 0.039 erms−/pix by nondestructively measuring the charge 5000 times in each pixel.

The Skipper-CCDs, a special type of charge-coupled device (CCD) sensor that features sub-electron readout noise levels, was proposed decades ago. However, only in recent years it has been possible to develop large size Skipper-CCDs ensuring stable operation. Their extreme low noise operation makes them suitable for experiments that require low thresholds and high energy resolution, such as dark matter and neutrino interactions detection, and more recently quantum-imaging and astronomy. New experiments are planning to use kilograms of active silicon from Skipper-CCDs as sensitive mass. In this way, they can achieve extremely low detection thresholds and a high probability of particle interaction. However, this approach needs arrays of thousands of Skipper- CCDs operating at the same time imposing challenging requirements. Also, introduction of this technology in astronomy and quantum-imaging applications requires a large number of channels per sensor to speed up the readout. The front-end needs to be redesigned from scratch: it must achieve low noise performance, be simple for easy integration and allow the routing of thousands of channels out of the sensors with minimal connections. This paper presents a detailed analysis of options for the front-end electronics and their noise performance. It describes a novel way of using a dual-slope integrator with minimal components to pile up the charge of consecutive readouts of the same pixel in a concept that we call a multi-slope integrator. This reduces drastically the output bandwidth, simplifying the wiring and the warm electronics. These proposals will allow the generation of new scientific instruments based on Skippers-CCD arrays.

The CONNIE experiment is located at a distance of 30 m from the core of a commercial nuclear reactor, and has collected a 3.7 kg-day exposure using a CCD detector array sensitive to an $\sim$1 keV threshold for the study of coherent neutrino-nucleus elastic scattering. Here we demonstrate the potential of this low-energy neutrino experiment as a probe for physics Beyond the Standard Model, by using the recently published results to constrain two simplified extensions of the Standard Model with light mediators. We compare the new limits with those obtained for the same models using neutrinos from the Spallation Neutron Source. Our new constraints represent the best limits for these simplified models among the experiments searching for CE$\nu$NS for a light vector mediator with mass $M_{Z^{\prime}}, Comment: Accepted for publication in JHEP

A baseband model for a polar RF modulator based on uniform sampling (US) pulse width modulation (PWM) is presented. RF-PWM allows to encode a complex baseband signal (amplitude and phase) into the pulse width and pulse position of a binary signal towards an efficient and fully digital RF transmitter implementation. We extend the well-known derivation of the naturally sampled (NS) RF-PWM to obtain a detailed model of the US RF-PWM which includes the intrinsic inband and side-bands distortion. In RF-PWM the carrier frequency is equal to the PWM frequency (first PWM harmonic). We develop the model such that the first or any other higher harmonic of the PWM can be used as the carrier signal. The distortion signal is analyzed in detail and a discrete-time implementation of the model which relates to previous approaches is presented. This model is key to the analysis, characterization and simulation of a fully digital transmitter. Fil: Chierchie, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: González, Gustavo José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Morales, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Paolini, Eduardo Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina Fil: Cousseau, Juan Edmundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Mandolesi, Pablo Sergio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina

This brief exhibits the relationship between the analog click modulator, which produces a binary pulse width modulation (PWM) signal with separated baseband, and recently reported fully digital, baseband distortion-free PWM algorithms (BBDFPWM). We show that BBDFPWM not only is a discrete-time version of the click modulator but also can operate in real-time without any shortcoming of other implementations. The method can also be used for developing low distortion and efficient arbitrary signal generators. In this case, we show a procedure for the offline computation of the duty-cycles of the PWM signal with zero distortion. Fil: Chierchie, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Paolini, Eduardo Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina

The Coherent Neutrino-Nucleus Interaction Experiment (CONNIE) uses low-noise fully depleted charge-coupled devices (CCDs) with the goal of measuring low-energy recoils from coherent elastic scattering (CE$\nu$NS) of reactor antineutrinos with silicon nuclei and testing nonstandard neutrino interactions (NSI). We report here the first results of the detector array deployed in 2016, considering an active mass 47.6 g (8 CCDs), which is operating at a distance of 30 m from the core of the Angra 2 nuclear reactor, with a thermal power of 3.8 GW. A search for neutrino events is performed by comparing data collected with reactor on (2.1 kg-day) and reactor off (1.6 kg-day). The results show no excess in the reactor-on data, reaching the world record sensitivity down to recoil energies of about 1 keV (0.1 keV electron-equivalent). A 95% confidence level limit for new physics is established at an event rate of 40 times the one expected from the standard model at this energy scale. The results presented here provide a new window to low-energy neutrino physics, allowing one to explore for the first time the energies accessible through the low threshold of CCDs. They will lead to new constrains on NSI from the CE$\nu$NS of antineutrinos from nuclear reactors., Comment: Updated to match the version accepted for publication in Physical Review D

Programmable delay lines are often used to provide precise transition timing control in very-large-scale integration (VLSI) systems. In this work, a digitally controlled delay line that achieves a resolution step of 340 ps and a maximum delay of 50 ns is proposed. The delay element has a linear delay characteristic and calibration capabilities in a range of 20% using a mixed model of current starving and load switching strategy. Experimental results of the circuit implementation in a 130-nm CMOS process are presented.

An all-digital high-resolution symmetric pulse-width modulator based on a custom delay integrated circuit is presented. The topology uses two complementary trailing-edge PWM signals from an FPGA to set the coarse adjustment of the symmetric duty-cycles, and the fine adjustment is provided by digitally-controlled delay lines with adjustable time resolution, implemented in a custom integrated circuit. More than 20 dB of reduction in the total harmonic distortion plus noise (THD+N) was measured with the proposed approach for a 1 kHz signal.

An all-digital high-resolution pulse-width modulator in standard 130-nm CMOS technology is presented in this work. The architecture is based on a digitally-controlled delay element with variable time interval up to 50 ps and adjustable against process, voltage and temperature (PVT) variations. Post-layout simulation results show a linear response between the control word and delay. The PWM modulator uses several delay elements in a hybrid configuration that allows to obtain duty cycles with 18-bit resolution, without using a high-frequency internal clock while maintaining low power consumption.

This article provides a design methodology to calculate an optimal filter for noise reduction in the readout of charge-coupled devices (CCDs) taking into account the charge transfer and feed-through due to capacitive coupling in the CCD. A detailed analysis of the dynamics in the video signal and charge transfer is presented. This includes the circuital modeling of the output stage of the CCD and the dynamics of the electronics in the video chain before the AD converter. The model is used to compute an optimal filter that minimizes the variance of the pixel noise and uses the samples of the charge transfer, before the charge is fully settled. This allows to shorten the pixel-time resulting in fastest readouts. The paper shows novel results of this processing in particular for Skipper CCD which uses a floating sense node to measure the charge packet.

In this paper, a novel pulse-width modulator (PWM) for an all-digital PWM transmitter based on switching amplification is presented. In this approach, each symbol is represented by a sequence of pre-computed PWM pulse widths stored in a table that results in reduced error vector magnitude (EVM). A high-resolution pulse former is then used to build the bipolar radio frequency (RF) signal. Simulations and comparisons to other approaches reported in the literature under different oversampling ratios and finite time resolutions are presented. The impact of nonlinearities in the variable duty-cycle generator is also analyzed to demonstrate the robustness of the proposed technique. Fil: Morales, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Chierchie, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Mandolesi, Pablo Sergio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Paolini, Eduardo Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina

In this paper we present a modulator for an all-digital pulse-width modulated (PWM) transmitter based on switching amplification. In this approach, each symbol is represented by a sequence of pre-computed PWM pulse widths stored in a table that results in reduced Error Vector Magnitude (EVM), achieving low distortion with a reduced pulse-rate. The modulator is implemented in a field programmable gate array (FPGA) device. The performance of this approach is compared to a standard uniform PWM modulator. Measurements using 64-QAM signals show a reduction of EVM values from 11.61% (-18.7 dB) for uniform PWM to 2.41%(-32.4 dB) for the proposed approach.

A fully digital algorithm to shape the spectrum of dead-time distortion in power inverters is presented. Dead-time is required to avoid short circuits of the power source by the legs of a power inverter due to the finite turn-ON and turn-OFF times of the switches. Dead-timemodifies the pulsewidths of the pulsewidth modulated (PWM) signal causing high harmonic distortion. The proposed approach is based on the time-to-digital conversion of the pulsewidths at the output of the power stage and does not require to measure the sign of the current, which is the preferred approach for dead-time compensation algorithms. The effect of the parasitic capacitance of the switching device that distorts the switching waveform is also analyzed and corrected. Furthermore, the quantization noise produced by digital PWM is also reduced by the proposed approach and has a minimal computational cost. Hardware-in-the-loop simulations are provided to show the effectiveness of the proposed approach, and experimental results using anH-bridge voltage-source inverter are included. A minimum total harmonic distortion plus noise (THD+N) of 0.027% was achievedfor a 1-kHz input driving an inductive load. Fil: Chierchie, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Paolini, Eduardo Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Stefanazzi, Leandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina

A fully-digital algorithm to shape the spectrum of dead-time distortion in power inverters is presented. Dead-time is required to avoid short circuits of the power source by the legs of a power inverter due to the finite turn-on and turn-off times of the switches. Dead-time modifies the pulse widths of the PWM signal causing high harmonic distortion. The proposed approach is based on measuring the pulse widths at the output of the power stage, and does not require to measure the sign of the current, which is usually necessary for dead-time compensation algorithms. Furthermore, the quantization noise produced by digital PWM is also reduced, and it has a minimal computational cost.

Fully depleted thick CCDs have been designed for infrared astronomy, but their low read-out noise of the order of a 2 e− and their considerable mass of a 5.2g, allows novel uses for them in low energy threshold particle detection applications, such as the CONNIE and DAMIC experiments. For both experiments, a reduction of the CCD read-out noise is will produce an increase in the detection efficiency. Few works have demonstrated that is possible reduce the noise applying digital processing techniques, and it is a field that must be explored. In this work the design of a CCD digital acquisition system will be presented. The impact of key parameters as quantization noise, front-end gain and ADC noise will be analyzed. A prototype of the front-end electronics was successfully tested with a CCD exposed to X-rays, achieving 2.3e− of readout noise.

Fully depleted thick CCDs have been designed for infrared astronomy, but their low read-out noise of the order of approximately 2 e− and their considerable mass of approximately 5.2 gr, allows novel uses for them in low energy threshold particle detection applications, such as the CONNIE and DAMIC experiments. In both experiments, the neutrinos or WIMPS will generate e-h pairs in a volume much less than the pixel size, they will produce events like points in the output image, of less than 10 pixels. Is well understood that one of the factors that define the size of the events is the diffusion process. In this work we will demonstrate with experimental results and through simulation, that there is also a dependence of the size with the amount of charge generated by the event, due to charge repulsion effects.

A real-time, digital algorithm for pulse width modulation (PWM) with distortion-free baseband is developed in this paper. The algorithm not only eliminates the intrinsic baseband distortion of digital PWM but also avoids the appearance of side-band components of the carrier in the baseband even for low switching frequencies. Previous attempts to implement digital PWM with these spectral properties required several processors due to their complexity; the proposed algorithm uses only several FIR filters and a few multiplications and additions and therefore is implemented in real time on a standard DSP. The performance of the algorithm is compared with that of uniform, double-edge PWM modulator via experimental measurements for several bandlimited modulating signals. Fil: Chierchie, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Investigación En Ingeniería Eléctrica; Argentina. Universidad Nacional del Sur. Departamento de Ingenieria Electrica y de Computadoras; Argentina Fil: Paolini, Eduardo Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Investigación En Ingeniería Eléctrica; Argentina. Universidad Nacional del Sur. Departamento de Ingenieria Electrica y de Computadoras; Argentina Fil: Stefanazzi, Leandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Investigación En Ingeniería Eléctrica; Argentina. Universidad Nacional del Sur. Departamento de Ingenieria Electrica y de Computadoras; Argentina Fil: Oliva, Alejandro Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Investigación En Ingeniería Eléctrica; Argentina. Universidad Nacional del Sur. Departamento de Ingenieria Electrica y de Computadoras; Argentina

The effect of dead-time on the spectrum of pulsewidth modulated signals is analyzed in this paper. The study is valid for arbitrary, band-limited modulating signals, extending previous results in the literature. A simple distortion index is developed that can be used at the design stage to select dead-time or switching frequency based on maximum allowed distortion. Experimental results with various band-limited signals reveal a very good agreement between the theoretical results and the experiments. Fil: Chierchie, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Investigación En Ingeniería Eléctrica; Argentina. Universidad Nacional del Sur. Departamento de Ingenieria Electrica y de Computadoras; Argentina Fil: Stefanazzi, Leandro. Universidad Nacional del Sur. Departamento de Ingenieria Electrica y de Computadoras; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Investigación en Ingeniería Eléctrica; Argentina. Instituto Nacional de Tecnologia Industrial; Argentina Fil: Paolini, Eduardo Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Investigación En Ingeniería Eléctrica; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Universidad Nacional del Sur. Departamento de Ingenieria Electrica y de Computadoras; Argentina Fil: Oliva, Alejandro Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Investigación En Ingeniería Eléctrica; Argentina. Universidad Nacional del Sur. Departamento de Ingenieria Electrica y de Computadoras; Argentina

The CONNIE Experiment (Coherent Neutrino Nucleus Interaction Experiment) is currently collecting reactor neutrino data to search for the undiscovered standard model process of coherent neutrino-nucleus scattering (CNNS). The detector is composed of a silicon target of thick, fully-depleted, low-noise CCD detectors. Results from data collected in 2015 indicate backgrounds are controlled, and allow an estimate of sensitivity to be presented for a larger scale detector. A 2016 upgrade, adding additional target mass, and reducing readout noise, has been performed, increasing the total yield of signal events by a factor of 30, and already yielding science-quality data. Low-energy nuclear calibrations have been performed, enabling calibration down to the device energy threshold. An estimate of the sensitivity expected for measuring the coherent neutrino process is presented. Future prospects with improved detector energy thresholds are estimated.

A discrete-time pulse width modulator (PWM) with zero baseband distortion for arbitrary band-limited modulating signals is developed in this paper. It is based on adjusting the duty-cycles of the PWMsuch that the samples of an ideal low-pass filtered version of the PWM signal coincide with the discrete-time samples of the modulating signal. Elaborating on previous approaches in the literature, it is shown that this problem can be stated as a multidimensional inverse function approach, and therefore it can be solved using iterative methods. Starting with the duty-cycle values of a uniform PWM, the successive iterations provide slight duty-cycle corrections that, in the limit, result in zero baseband distortion even for low carrier-to-modulating frequency ratios. Aiming at a practical, real-time implementation two new results are provided. First, explicit bounds on the improvement achievable after each duty-cycle correction are derived. Second, a block processing architecture suitable for real-time implementation is proposed, and the increase of distortion caused by its use is quantified. Several examples with typical band-limited signals demonstrate the performance of the algorithm. Fil: Chierchie, Fernando. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Bahia Blanca. Instituto de Invest.en Ing.electrica; Argentina; Fil: Paolini, Eduardo Emilio. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Bahia Blanca. Instituto de Invest.en Ing.electrica; Argentina

An alias-free, discrete-time click modulator is developed in this paper. Previous approaches rely on translating the continuous-time click modulator to a discrete-time setting, although a key component in the click modulator - the analytic exponential modulator-cannot be exactly transformed to the discrete domain. Every discrete-time version of the click modulator reported in the literature is prone to aliasing effects that are ameliorated, but not eliminated, using interpolation techniques. The precision of the switching times of the output square wave is critical to click modulation because uncertainties in their determination adversely affect the performance and SNR of the modulator. A novel method that uses frequency domain information to compute these switching times without error is also presented. This two techniques are used to develop an off-line discrete-time click modulator that achieves a SNR larger than 180 dB for both multitonal and bandpass signals.

Fully depleted thick CCDs have been designed for infrared astronomy, but their low read-out noise of the order of ≈2e− and their considerable mass of ≈5.2 gr, allows novel uses for them in low energy threshold particle detection applications, such as the CONNIE and DAMIC experiments. For both experiments, a reduction of the CCD read-out noise is vital. In this work we present a method to measure the read-out noise coming from electronic and non-electronic sources. The impact of the external electronics on the noise is discussed and its full characterization is presented.

This paper presents an adaptive digital predistorter (DPD) that significantly reduces the baseband distortion of digital pulse width modulation (PWM), typically used in switching (class-D) amplifiers. A generalized Hammerstein structure (also known as power filter) composed by static nonlinearities and FIR filters is used to model the baseband behavior of PWM. We show that the contribution of the higher order terms of the nonlinearity are negligible and therefore, for practical applications, only the first three or four odd powers should be retained. The convergence of the DPD is studied and the performance is demonstrated and compared with other approaches. Good results are obtained for typical signals even when using low-order FIR filters in the DPD. Measurement results obtained using a digital signal processor are also presented aiming to validate the proposed approach. Fil: Chierchie, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica ; Argentina Fil: Cousseau, Juan Edmundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica ; Argentina Fil: Paolini, Eduardo Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica ; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina Fil: Stefan Werner. Aalto University; Finlandia

The first period-doubling bifurcation of a dc–dc buck converter controlled by a zero-average dynamic strategy is studied in detail. Owing to the saturation of the duty cycle, this bifurcation is followed by a border-collision bifurcation, which is the main mechanism to introduce instability and chaos in the circuit. The multiparameter analysis presented here leads to a complete knowledge of the relatioship between these two bifurcations. The results are obtained by using a frequency-domain approach for the study of period-two oscillations in maps. Copyright © 2010 John Wiley & Sons, Ltd. (The ∞-norm of a matrix A is defined as ∥A∥ = maxij|aij|. In particular, |aij|⩽∥A∥ for all i and j.)

In this article the feasibility of using charge coupled devices (CCD) to detect low-energy neutrinos through their coherent scattering with nuclei is analyzed. The detection of neutrinos through this standard model process has been elusive because of the small energy deposited in such interaction. Typical particle detectors have thresholds of a few keV, and most of the energy deposition expected from coherent scattering is well below this level. The CCD detectors discussed in this paper can operate at a threshold of approximately 30 eV, making them ideal for observing this signal. On a CCD array of 500 g located next to a power nuclear reactor the number of coherent scattering events expected is about 3000 events/year. Our results shows that a detection with a confidence level of 99% can be reached within 16 days of continuous operation; with the current 52 g detector prototype this time lapse extends to five months. Fil: Fernández Moroni, Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Investigación En Ingeniería Eléctrica; Argentina. Universidad Nacional del Sur; Argentina. Fermi National Accelerator Laboratory; Estados Unidos Fil: Estrada, Juan. Fermi National Accelerator Laboratory; Estados Unidos Fil: Paolini, Eduardo Emilio. Universidad Nacional del Sur; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina Fil: Cancelo, Gustavo Indalecio Eugenio. Fermi National Accelerator Laboratory; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Tiffemberg, Javier. Fermi National Accelerator Laboratory; Estados Unidos Fil: Molina, Jorge. Universidad Nacional de Asuncion; Paraguay

A frequency-analytic methodology for controlling the amplitudes and stability of Neimark-Sacker bifurcations exhibited by discrete-time systems is presented. The proposed controller consists of a nonlinear static feedback law and a highpass filter used to preserve the dynamical behaviors of the system's equilibria. A simple example is included to illustrate the application of the method.

A nonlinear digital controller for improving the dynamical behavior of a buck converter operating in discontinuous conduction mode is presented. The aim is the extension of the operating range of the circuit, ameliorating the appearance of period-two orbits when the resistive load or the source voltage are varied. The controlled system is analyzed by using a frequency-domain technique. Numerical and experimental results are included to illustrate the performance of the system.

In this paper, bifurcation theory is employed to classify different dynamical behaviors arising in an underactuated mechanical system subject to bounded controls. The methodology is applied to an inertia wheel pendulum consisting of a simple pendulum with a rotating disk at the end. Restricting the magnitude of the control action places an important obstacle to the design of a continuous controller capable of swinging-up and stabilize the pendulum at the inverted position: the arm only can reach that position by means of oscillations of increasing amplitude. The controller is derived from a simple nonlinear state-feedback law, followed by a saturating device that limits the maximum amplitude of the control action applied to the system. This bound gives birth to a rich dynamical behavior, including pitchfork and Hopf bifurcations of equilibria, saddle-node bifurcations of periodic orbits, homoclinic and heteroclinic bifurcations. The global dynamics is analyzed in terms of certain control gains and a two-parameter bifurcation diagram is derived. It is shown that the dynamics on this bifurcation diagram is organized in a pair of codimension-two rotationally symmetric bifurcation points. Finally, it is found out that when the control gains lie on a certain region in the parameter space simultaneous stabilization of the upright position together with a large basin of attraction is obtained. Simulation results show that almost global stabilization of the system can be achieved.

A frequency domain methodology for the approximation of period doubling bifurcations in discrete-time nonlinear systems is presented. The computation of a stability index, which characterizes the dynamical behavior of the emerging period-two orbit is also derived. The technique is applied to estimate the domain of attraction of the fixed point in an adaptive control system and to improve the dynamical behavior of a buck converter.

The application of the graphical Hopf theorem (GHT) as a tool for detecting invariant cycles in maps is presented. The invariant cycle emerging from the bifurcation is approximated using an analogous version of the GHT for continuous-time systems. This technique is formulated in the so-called frequency domain and it involves the use of the Nyquist stability criterion and the harmonic balance method. Some examples are included for illustration. Fil: D'amico, Edith Maria Belen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Moiola, Jorge Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Paolini, Eduardo Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina

This paper presents an initial approach to the development of a component for black box functional verification of FFT cores. First, a coverage model based on equivalence partitioning and boundary value analysis of the input signal space is defined, allowing to identify a set of test cases of interest. Then, the design and implementation of a SystemVerilog testbench is described and employed to stimulate three FFT IPs, performing a coverage driven verification procedure for checking performance, configurations and accuracy correctness.

The control of nonlinear systems exhibiting bifurcation phenomena has been the subject of active research in recent years. Contrary to regulation or tracking objectives common in classic control, in some applications it is desirable to achieve an oscillatory behavior. Towards this end, bifurcation control aims at designing a controller to modify the bifurcative dynamical behavior of a complex nonlinear system. Among the available methods, the so-called "anti-control" of Hopf bifurcations is one approach to design limit cycles in a system via feedback control. In this paper, this technique is applied to obtain oscillations of prescribed amplitude in a simple mechanical system: an underactuated pendulum. Two different nonlinear control laws are described and analyzed. Both are designed to modify the coefficients of the linearization matrix of the system via feedback. The first law modifies those coefficients that correspond to the physical parameters, whereas the second one changes some null coefficients of the linearization matrix. The latter results in a simpler controller that requires the measurement of only one state of the system. The dependence of the amplitudes as function of the feedback gains is obtained analytically by means of local approximations, and over a larger range by numerical continuation of the periodic solutions. Theoretical results are contrasted by both computer simulations and experimental results.

The readout noise for Charge-Coupled Devices (CCDs) has been the main limitation when using these detectors for measuring small amplitude signals. A scientific CCD fabricated on a high-resistivity silicon substrate utilizing a floating gate amplifier with the capability of multiple sampling of the charge signal is described in this paper. The Skipper CCD architecture and its advantages for low noise applications are discussed. A technique for obtaining sub-electron readout noise levels is presented, and its noise and signal characteristics are derived. We demonstrate that with this procedure a very low readout noise of 0.2e − RMS can be achieved. The contribution of other noise sources (output stage, vertical and horizontal charge transfer inefficiency, and dark current noise) are also considered. The optimum number of samples for achieving the total lowest possible noise level is obtained. This technique is applied to an X-rays experiment using a 55Fe source. Fil: Fernández Moroni, Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina. Fermi National Accelerator Laboratory; Estados Unidos Fil: Estrada, Juan. Fermi National Accelerator Laboratory; Estados Unidos Fil: Cancelo, Gustavo. Fermi National Accelerator Laboratory; Estados Unidos Fil: Paolini, Eduardo Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina Fil: Diehl, Thomas. Fermi National Accelerator Laboratory; Estados Unidos

The analytical spectrum of pulse width modulated (PWM) signals with dead-time is derived in this paper. Previous results were based on the double Fourier series expansion and therefore they are only valid for a single tone modulating signal. In this work analytical expressions for finite bandwidth input signals are presented. Some simplifying assumptions are considered to derive manageable expressions; however, extensions to more general cases are straightforward. Theoretical results are compared with computer simulations.

A methodology to characterize the uncertainty description of nominal stable, time invariant linear control systems based on frequency response measurements is presented. The frequency response of the uncertain plant is modeled using series of Laguerre orthonormal functions. An algorithm to test robust stability is developed. A gain margin measure is also given.

A novel method is presented for controlling the amplitudes and stability of orbits generated from Neimark-Sacker bifurcations in discrete-time systems. The technique es rooted in the frequency-domain approach for the study of bifurcations in maps. Fil: D'amico, Edith Maria Belen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Chen, Guanrong. City University Of Hong Kong; China Fil: Paolini, Eduardo Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Moiola, Jorge Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina