Papers by Alfonso Carlosena
IEEE International Symposium on Circuits and Systems, 1998
Significant departures between predicted behaviour and actual performance are observed in opamp b... more Significant departures between predicted behaviour and actual performance are observed in opamp based structures containing the so called MOS resistive circuit. In this paper we demonstrate that the usual description of this cell by a simple model of two tunable resistors is not adequate enough to properly shape the MRC operation. A more complete, though still simple model is proposed
IEEE Instrumentation and Measurement Technology Conference, 2001
This paper addresses the problem of measuring the acoustic frequency response of auditoria and lo... more This paper addresses the problem of measuring the acoustic frequency response of auditoria and loudspeaker characterization. The difficulty of the problem is illustrated with a number of measurements performed using different methods and equipment. The use of multitone signals both uniformly and logarithmically spaced is proposed to obtain fast and reproducible measurements
2010 53rd IEEE International Midwest Symposium on Circuits and Systems, 2010
ABSTRACT In this paper we describe a novel procedure to design high-type high-order Phase Locked ... more ABSTRACT In this paper we describe a novel procedure to design high-type high-order Phase Locked Loops (PLLs) from lower order prototypes, preserving a prescribed Phase Margin (PM). The method builds on a model recently proposed by the authors, and is supported by extensive simulations and experimental results, giving up to a type-III fifth-order PLL with a commercial circuit.
Proceedings of the 33rd Midwest Symposium on Circuits and Systems, 1991
The frequency limitations associated with single-op amp-based oscillators are analysed. It is sho... more The frequency limitations associated with single-op amp-based oscillators are analysed. It is shown how they can be improved, extending their range of operation and reducing the harmonic distortion without introducing either active or passive additional elements. Experimental results are given showing a close agreement with theoretical predictions
2008 51st Midwest Symposium on Circuits and Systems, 2008
ABSTRACT Phase Noise Frequency response in a Phase Locked Loop cannot be freely determined, since... more ABSTRACT Phase Noise Frequency response in a Phase Locked Loop cannot be freely determined, since it is constrained by the Loop structure and the Loop Filter (LF) shape. Therefore, Filter Approximation Theory is of no use in this case. However, we show in this paper that some general relations can be established between the Loop Filter, Loop Gain, and Phase Noise Frequency response, making it possible to apply basic filter theory concepts to PLL design. This approach can be seen as complementary to the conventional way PLLs are analysed.
2014 IEEE 11th International Multi-Conference on Systems, Signals & Devices (SSD14), 2014
ABSTRACT Practical designs of Type III PLL are scarce, and even they have been sometimes consider... more ABSTRACT Practical designs of Type III PLL are scarce, and even they have been sometimes considered impossible. In this paper we present for the first time a performance comparison between Type II and Type III PLLs. The analysis is based on a powerful model previously presented by the authors. In particular the advantages of type III PLLs over type II to follow chirp signals, without compromising stability, are demonstrated. Approximated closed form expressions are proposed to evaluate Type III PLL performance.
2006 IEEE Instrumentation and Measurement Technology Conference Proceedings, 2006
In this communication, the problem of blind deconvolution of transient, impulsive signals in a mu... more In this communication, the problem of blind deconvolution of transient, impulsive signals in a multichannel environment is addressed. This kind of signals arise naturally, or are used as external excitation, in many mechanical and acoustical systems and can only be observed indirectly, after propagation through the medium. Blind deconvolution or identification methods published to date are not suitable for recovering these sources or the system response, as identifiability conditions are not met. We fully develop here a deterministic subspace method for the blind deconvolution in a multichannel environment which does not impose any restrictions on the excitation signals or on the impulse response of propagation channels, apart from finite length and channel diversity. The method is also extended to cope with signals in noisy environments.
IEEE Transactions on Circuits and Systems Ii-express Briefs, 2007
The analysis, and design of third-order, (and higher) phase-locked loops (PLL) is difficult. This... more The analysis, and design of third-order, (and higher) phase-locked loops (PLL) is difficult. This paper presents a novel approach to overcome these difficulties by allowing high-order loops to be viewed as a natural extension of lower order ones. This is accomplished by adding nested first-order feedback loops around a basic first-order loop filter. Our approach will also be related to
2006 IEEE International Symposium on Circuits and Systems, 2006
A 1.5-V Square-Root Domain (SRD) first-order filter possessing multiple operating points is prese... more A 1.5-V Square-Root Domain (SRD) first-order filter possessing multiple operating points is presented. The basic building blocks of the filter are based on MOS translinear loops and dynamic level shifter techniques, allowing low voltage operation and an extended dynamic range. However the dynamic level shifters introduce positive feedback inducing three operating points to the filter through a negative differential resistance. A detailed analysis of such performance employing a bi-port analysis is offered. Simulation and measurement results are provided in order to demonstrate the analysis and circuits proposed. ISCAS 2006 0-7803-9390-2
2009 IEEE Intrumentation and Measurement Technology Conference, 2009
Abstract Single-event impulsive signals abound in acoustic systems. They are characterized by a c... more Abstract Single-event impulsive signals abound in acoustic systems. They are characterized by a confinement of their energy in a short time interval, and they usually arise, intentional or unintentionally, from explosive acoustic sources. They can seldom be observed directly, ...
2004 IEEE International Symposium on Circuits and Systems (IEEE Cat. No.04CH37512), 2004
This paper presents a new compact low-voltage differential linear transconductor. The proposed tr... more This paper presents a new compact low-voltage differential linear transconductor. The proposed transconductor is based on a straightforward modification of a classical scheme that leads to class-AB linear operation. The transconductor has been designed using a 0.8 μm CMOS technology (VT ∼ 0.8 V) and it is operated at 1.5 V with only 42 μW of quiescent power consumption and
IMTC/99. Proceedings of the 16th IEEE Instrumentation and Measurement Technology Conference (Cat. No.99CH36309), 1999
ABSTRACT This paper is focussed on a low cost modular instrumentation system achievement. A GPIB ... more ABSTRACT This paper is focussed on a low cost modular instrumentation system achievement. A GPIB interface target using VLSI specialized integrated circuits and several middle capabilities programmable instrument targets have been designed to provide a complete and versatile instrumentation system using a support bus to interconnect the different module-instrument STD backplane. A computer-based virtual instrument (VI) which can perform a dynamical characterization of DC-DC switching converters has been implemented using this modular instrument, the VI is devoted to the test of the PWM devices used as duty cycle controllers in the design of switched DC-DC converters. Such VI has been implemented using a switching module which has been designed as a plug-in card in the STD bus instrumentation system, performing both signal routing and data acquisition. As an example, Yin and Z out characterization of a PWM-based Boost converter have been obtained
2007 IEEE Sensors Applications Symposium, 2007
This paper describes the technologies used in coin discriminator devices, stressing the improveme... more This 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.
9th International Conference on Electronics, Circuits and Systems, 2002
A first-order CMOS log-domain filter is presented. The internal voltage swing compression due to ... more A first-order CMOS log-domain filter is presented. The internal voltage swing compression due to its companding nature, together with the use of floating-gate MOS transistors and its class AB differential topology, allows the filter to operate at 1V while maintaining at the same time a large input range. Moreover, operation in weak inversion leads to very low power consumption. Simulation
2008 IEEE Instrumentation and Measurement Technology Conference, 2008
In this paper, we propose a method for detecting the characteristics of different materials that ... more In this paper, we propose a method for detecting the characteristics of different materials that have similar properties, by classifying their responses when impacted with small hard spheres. First, a signal conditioning and data compression stage are described. Then a multilayer neural network is used to detect the individual patterns of the samples, and classify the signal. The results of
2007 IEEE Instrumentation & Measurement Technology Conference IMTC 2007, 2007
In this paper, we propose a novel approach to characterize the response of the piezoelectric acce... more In this paper, we propose a novel approach to characterize the response of the piezoelectric accelerometers in a wide frequency range. The method consists in exciting the sensor by a pulse produced by the impact of a high-stiffness and smallmass sphere. First, we give some physical grounds on the impact phenomenon. Then, we propose a simple experimental set-up, and suggest how to tune it at its best. We emphasize the convenience of conditioning the sensors by a differential charge amplifier if this is feasible. Finally, we apply the impact-method to two commercial sensors. As a result, we managed to characterize one of them in a bandwidth up to 250 kHz, detecting up to three resonance frequencies. We discuss the advantages of this technique in comparison with the standard calibration methods.
2009 IEEE Sensors, 2009
A detailed comparison of integrated CMOS charge amplifiers is presented in this work. Conventiona... more A detailed comparison of integrated CMOS charge amplifiers is presented in this work. Conventional topologies, along with new ones, have been fabricated in a CMOS test chip prototype and their measured performance compared in terms of sensitivity, PSRR, and frequency response. As a result of this work, a complete library of fabricated CMOS charge amplifiers is presented and the performance tradeoffs of each solution discussed. This way the designer can make an educated choice about the design that best suits some given specs.
2009 52nd IEEE International Midwest Symposium on Circuits and Systems, 2009
In this paper a Spice model of magnetoimpedance sensors is proposed. The model is based on the eq... more In this paper a Spice model of magnetoimpedance sensors is proposed. The model is based on the equivalent circuits of a Padé's approximation derived from the impedance relied on Bessel functions. The resulting model is fast and acceptably accurate since only lumped electrical passive elements are required. Besides, it can predict the nonlinear frequency response from DC to several megahertz taking into account the transverse permeability changes due to an external magnetic field. The model is verified using Spice simulations together with measurements results from a discrete prototype for generating the pulse voltage source and a simple modulation type configuration.
… 2005, Autumn, núm …, 2005
SIAM Journal on Matrix Analysis and Applications, 2008
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Papers by Alfonso Carlosena