3.
Electrical measurement of the junction temperature
and thermal resistance of HBTs - Melczarsky, Ilan; Lonac, Julio A.; Filicori, Fabio
A simple method is proposed to derive the junction temperature and the bias- and temperature-dependent thermal resistance of heterojunction bipolar transistors (HBTs) using a radio frequency (RF) signal. The method exploits the thermal dependence of the current gain of a transistor whose dissipated power is modified by applying an RF signal. The new method is used to derive the junction temperature and thermal resistance of a power HBT. The results are compared with state-of-the-art techniques.
4.
A new technique for thermal resistance measurement in power electron devices - Filicori, Fabio; Rinaldi, Paola; Vannini, Giorgio; Santarelli, Alberto
A simple technique is proposed for the thermal resistance measurement of electron devices. The new approach is based on the standard measurements which are normally carried out for the electrical characterization of power devices, without requiring special-purpose instrumentation and/or physics-based temperature-dependent electrical device models. Experimental results, which confirm the validity of the new method, are provided.
5.
Accurate pHEMT nonlinear modeling in the presence of low-frequency dispersive effects - Raffo, Antonio; Santarelli, Alberto; Traverso, Pier Andrea; Vannini, Giorgio; Palomba, Francesco; Scappaviva, Francesco; Pagani, Maurizio; Filicori, Fabio
Low-frequency (LF) dispersive phenomena due to device self-heating and/or the presence of "traps" (i.e., surface state densities and bulk spurious energy levels) must be taken into account in the large-signal dynamic modeling of III-V field-effect transistors when accurate performance predictions are pursued, since these effects cause important deviations between direct current (dc) and dynamic drain current characteristics. In this paper, a new model for the accurate characterization of these phenomena above their cutoff frequencies is presented, which is able to fully exploit, in the identification phase, large-signal current-voltage (I-V) measurements carried out under quasi-sinusoidal regime using a recently proposed setup....
6.
Hardware implementation of a broad-band vector spectrum analyzer based on randomized sampling - Pasini, Gaetano; Traverso, Pier Andrea; Mirri, Domenico; Iuculano, Gaetano; Filicori, Fabio
A hardware prototype of vector spectrum analyzer, which is based on a randomized sampling strategy and associated alias-free digital signal processing (DSP) algorithms, has been fully designed and implemented. The instrument exploits a couple of identical independently programmable digital data acquisition channels, whose synchronization allows to sample the input signal at instants that can be very close along the time axis (tens of picoseconds), against a maximum single-channel average throughput rate of 250 ksamples per second (kSa/s). This architecture has shown to be suitable for the accurate implementation of the randomized periodic sampling with uniform jitter on which the instrument...
7.
A nonlinear dynamic model for performance analysis of large-signal amplifiers in communication systems - Mirri, Domenico; Filicori, Fabio; Iuculano, Gaetano; Pasini, Gaetano
A new nonlinear dynamic model of large-signal amplifiers based on a Volterra-like integral series expansion is described. The new Volterra-like series is specially oriented to the modeling of nonlinear communication circuits, since it is expressed in terms of dynamic deviations of the complex modulation envelope of the input signal. The proposed model represents a generalization, to nonlinear systems with memory, of the widely-used amplitude/amplitude (AM/AM) and amplitude/phase (AM/PM) conversion characteristics, which are based on the assumption of a practically memoryless behavior. A measurement procedure for the experimental characterization of the proposed model is also outlined.
8.
A nonlinear dynamic S/H-ADC device model based on a modified Volterra series: identification procedure and commercial CAD tool implementation - Traverso, Pier Andrea; Mirri, Domenico; Pasini, Gaetano; Filicori, Fabio
A nonlinear, dynamic empirical model, based on a Volterra-like approach, was previously proposed by the authors for the time-oriented characterization of sample/hold (S/H) and analog-to-digital conversion (ADC) devices. In this paper, the experimental procedure for model parameter measurement is presented, as well as techniques devoted to the implementation of the model in the framework of the main commercial CAD tools for circuit analysis and design. Examples of simulations, performed both in the time and frequency domain on the model obtained for a commercial device, are proposed, which show the model's capability of pointing out the dynamic nonlinear effects in the...
9.
Equivalent-voltage approach for modeling low-frequency dispersive effects in microwave FETs - Santarelli, A.; Zucchelli, G.; Paganelli, R.; Vannini, G.; Filicori, F.
In this paper, a simple and efficient approach for the modeling of low-frequency dispersive phenomena in FETs is proposed. The method is based on the definition of a virtual, nondispersive associated device controlled by equivalent port voltages and it is justified on the basis of a physically-consistent, charge-controlled description of the device. Dispersive effects in FETs are accounted for by means of an intuitive circuit solution in the framework of any existing nonlinear dynamic model. The new equivalent-voltage model is identified on the basis of conventional measurements carried out under static and small signal dynamic operating conditions. Nonlinear experimental tests...
10.
A modified Volterra series approach for nonlinear dynamic systems modeling - Mirri, Domenico; Iuculano, Gaetano; Filicori, Fabio; Pasini, Gaetano; Vannini, Giorgio; Pellegrini Gualtieri, Gabriella
This paper describes a modeling approach for nonlinear dynamic systems based on a modified Volterra series; by comparing the truncation error of this series with that of the classical Volterra one, we outlined that, under the assumption of short-term nonlinear memory effects, the modified series enables a single-fold nonlinear convolution integral to be adopted also in the presence of strong nonlinearities. The measurement-based identification of the first terms of the modified Volterra series is described; experimental and simulation results which confirm the theoretical considerations are also provided.
11.
Implementation and performance evaluation of a broad-band power spectrum analyzer - Pasini, Gaetano; Mirri, Domenico; Iuculano, Gaetano; Filicori, Fabio
A new technique for power spectrum analysis is introduced, theoretically evaluated, and experimentally verified with a prototype. This technique is based on the estimate of the autocorrelation function for different delays. The proposed sampling strategy is random in the time domain and equally spaced, synchronous with the signal, in the delay domain, It is shown that the estimate of the power spectral components is asymptotically unbiased, and the experimental results are also given
12.
Tool for efficient intermodulation analysis using conventional HB packages - Vannini, G.; Filicori, F.; Traverso, P.
A simple and efficient approach is proposed for the intermodulation analysis of nonlinear microwave circuits. The algorithm, which is based on a very mild assumption about the frequency response of the linear part of the circuit, allows for a reduction in computing time and memory requirement. Moreover. It can be easily implemented using any conventional tool for harmonic-balance circuit analysis
13.
A broad-band power spectrum analyzer based on twin-channel delayed sampling - Mirri, Domenico; Iuculano, Gaetano; Pasini, Gaetano; Filicori, Fabio; Peretto, Lorenzo
This paper describes a power spectrum analyzer whose bandwidth is not limited by the mean sampling time. The procedure is based on the estimation of the spectral components of the autocorrelation function of the input signal through the simultaneous random sampling of the given input signal and its randomly “delayed copy”. The samples are therefore randomly taken in a double-dimension space, time, and delay. By using a random process in the time domain with a recursive mean previously introduced by the authors in order to avoid any bandwidth limitation due to the sampling strategy, it is shown both theoretically and...
14.
Implementation and performance evaluation of a broadband digital harmonic vector voltmeter - Mirri, D.; Pasini, G.; Peretto, L.; Filicori, F.; Iuculano, G.; Dolfi, A.
A broadband digital harmonic vector voltmeter proposed previously and studied theoretically by the authors was implemented using a special-purpose, random sampling strategy, to avoid the bandwidth limitations due to the finite conversion time of the sample-and-hold and analog-to-digital-conversion (S/H-ADC) devices. The experimental results have shown that the bandwidth of the instrument is not limited by the finite conversion time of S/H-ADC devices, since good accuracy can be achieved even when the average sampling frequency is much lower than the signal bandwidth. The amplitude and phase uncertainty, with sinusoidal test signals up to 1 MHz and an average sampling rate of...
15.
The vector-gradient Hough transform - Cucchiara, R.; Filicori, F.
The paper presents a new transform, called vector-gradient Hough transform, for identifying elongated shapes in gray-scale images. This goal is achieved not only by collecting information on the edges of the objects, but also by reconstructing their transversal profile of luminosity. The main features of the new approach are related to its vector space formulation and the associated capability of exploiting all the vector information of the luminosity gradient
16.
The effect of time-jitter in equispaced sampling wattmeters - Mirri, D.; Iuculano, G.; Pasini, G.; Filicori, F.
This paper evaluates the effect of time-jitters in the equally spaced sampling wattmeters on the hypothesis of jitters uncorrelated with the input signals. The general case of two distinct time-jitters is considered, one common to the two channels and the other different for each one of them. The performance of the wattmeter has been evaluated by considering the asymptotic statistic parameters of the output. It has been shown that the different time-jitters introduce a bias and that both time-jitters contribute to the variance of the output. In any case, time-jitters introduce further bandwidth limitations which must be taken into account...
17.
A simplified thermal analysis approach for power transistor rating in PWM-controlled DC/AC converters - Filicori, F.; Guarino Lo Bianco, C.
A simplified dynamic thermal analysis approach is proposed for the estimation of the peak junction temperature in power IGBT transistors operating in pulse-width modulation (PWM) controlled DC/AC converters. This approach can be used for the rating of electron devices or heatsink systems in power circuit design, as it provides a direct analytical link, in terms of electrical and thermal device parameters and converter operating conditions between the case and the peak junction temperatures. In this way, by imposing a given upper limit on the junction temperature, indirect constraints on device size or load current or heatsink efficiency can easily be...
18.
'Backgating' model including self-heating for low-frequency dispersive effects in III-V FETs - Santarelli, A.; Filicori, F.; Vannini, G.; Rinaldi, P.
A new approach is proposed which takes into account both traps and thermal phenomena for the modelling of deviations between static and dynamic drain current characteristics in III-V field effect transistors. The model is based on the well-known `backgating' concept and can easily be identified on the basis of conventional static drain current characteristics and small-signal, low-frequency S parameters. Experimental results confirm the accuracy of the proposed model
19.
Physics-based large-signal sensitivity analysis of microwave circuits using technological parametric sensitivity from multidimensional semiconductor device models - Bonani, F.; Guerrieri, S.D.; Filicori, F.; Ghione, G.; Pirola, M.
The authors present an efficient approach to evaluate the large-signal (LS) parametric sensitivity of active semiconductor devices under quasi-periodic operation through accurate, multidimensional physics-based models. The proposed technique exploits efficient intermediate mathematical models to perform the link between physics-based analysis and circuit-oriented simulations, and only requires the evaluation of dc and ac small-signal (dc charge) sensitivities under general quasi-static conditions. To illustrate the technique, the authors discuss examples of sensitivity evaluation, statistical analysis, and doping profile optimization of an implanted MESFET to minimize intermodulation which makes use of LS parametric sensitivities under two-tone excitation
20.
A prototype controller for variable reluctance motors - Lo Bianco, C.G.; Tonielli, A.; Filicori, F.
A three-level cascade structure is proposed for the control of a variable reluctance (VR) motor. In order to deal with the highly nonlinear behavior of VR motors, the controlling system includes two variable-structure controllers for current and velocity loops as well as an intermediate torque-sharing compensator. The intermediate compensator has been designed by means of nonlinear optimization techniques in order to reduce the torque ripple and to get the maximum motor velocity. The proposed controller has been validated through extensive simulation experiments. The architecture of a prototype controller is presented and the actual performance measured on a VR motor is...
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