Domenico Mirri

A non-linear dynamic model for performance analysis of large-signal amplifiers in communication systems

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.

Recursive random-sampling strategy for a digital wattmeter

A recursive random-sampling strategy is proposed for the implementation of a digital broadband wattmeter. In this strategy each sampling instant is obtained by adding to the preceding one a predetermined constant lag plus a random increment. In order to correlate the measurement uncertainty to the bandwidth, the asymptotic mean-square error arising from the sampling strategy and the filtering algorithm is evaluated and analyzed; it has been shown that the proposed sampling strategy does not limit the bandwidth of the instrument if an appropriate statistical distribution of the random increments is selected. The theoretical results are compared with those obtained by simulating the measurement process. >

Modeling of non ideal dynamic characteristics in S/H-ADC devices

S[k]=S(tk) IDEAL ADC Abstruct A mathematical modelling approach is proposed for the modelling of non-ideal dynamic characteristics in SIH-ADC: devices. The method is based on the application of a modified Volterra series under the hypothesis of only short term memory effects. It is shown that a S/H-ADC device can be characterized, if the signal bandwidth is limited, by a static characteristic and a nonlinear transfer function, both depending on the input signal.

Non-linear dynamic system modelling based on modified Volterra series approaches

Abstract The empirical “black-box” characterization of non-linear systems with memory is a complex problem which cannot be dealt with by means of a unique, general-purpose mathematical approach such as the Volterra series. In fact, from a metrological point of view, the feasibility and reliability of the measurement procedure must be the criterion on the basis of which any mathematical approach for modelling purposes must be evaluated. This paper describes different solutions for the behavioural identification of non-linear dynamic systems, all based on a modified Volterra series, which are characterized by a reduced number of operators with respect to the classical Volterra approach. The operator reduction, which does not affect the accuracy of the obtained models if a mild assumption on the system memory time duration is satisfied, allows a reliable extraction of the model parameters by means of conventional instrumentation, without the need for the generation of complicated input probing signals or additional approximations. A detailed discussion is provided in order to estimate when each of the proposed approaches can be practically used, by pointing out the hypotheses that must be taken into account in order to minimise the modified series truncation errors. Experimental examples, showing the validity of the proposed approaches, are given in the last section of the paper, as well as a comparison between the performances of the different solutions when applied to the important field of electron device characterization.

A modified Volterra series approach for the characterization of non-linear dynamic systems

The paper presents a theoretical study on the convergence properties of the new modified Volterra-like modeling approach for non-linear dynamic systems in comparison with the classical Volterra series representation. In particular, the assumptions which enable a single-fold non-linear convolution integral to be adopted also in the presence of strong non-linearities are pointed out. Experimental and simulation results which confirm the theoretical considerations are also provided.

A non-linear dynamic S/H-ADC device model based on a modified Volterra series: identification procedure and commercial CAD tool implementation

A non-linear dynamic empirical model, based on a Volterra-like approach, was previously proposed by authors for the time-oriented characterization of S/H-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 main commercial CAD tools for circuit analysis and design. The results of simulations, performed on the obtained model both in time and frequency domain, are proposed which show model capability to point out the dynamic non-linear effects in the device response.

A broad-band harmonic vector voltmeter based on a random sampling strategy

This paper presents a digital harmonic vector voltmeter based on a random asynchronous sampling strategy. The measurement procedure is described and the problem of estimating both the error due to the time discretization and to the estimation of the periodic complex exponential associated with the input reference signal is discussed.<<ETX>>

CAD identification and validation of a non-linear dynamic model for performance analysis of large-signal amplifiers

We describe the CAD identification and software implementation of a Volterra-like integral series expansion for the behavioral-level simulation of communication amplifiers. The model represents an improvement with respect to the classical AM-AM AM-PM memoryless approach. The performance of the model is compared with both the AM-AM AM-PM approach and circuit-level CAD simulation.

New performance function for the comparison of different sampling strategies in non-linear conversion instruments

A method for the performance evaluation of digital measurement instruments based on asynchronous sampling and nonlinear signal conversion is proposed. The authors propose a performance index for the comparison of different asynchronous strategies and develop the analytical form of that index for two sampling techniques, equally spaced and random. The idea is to interpret the instantaneous output of the instrument as a discrete random variable with a uniform distribution over the successive occasions of measurement. Thus, the asymptotic variance of the reading can be a sum of contributions, each of which is obtained by weighting the contributions relative to each spectral component of the signal according to a frequency-dependent coefficient which is assumed to the performance index.<<ETX>>

Implementation and performance evaluation of a broad-band power spectrum analyzer

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.