R.V. Antipensky − Ph.D. (Eng.), Associate Professor, 

Chair of Radio Electronics, Military Educational-Scientific Center of Air Forces 

of the «Military-air academy named after professor N.E. Zhukovsky and Yu.A. Gagarin» (Voronezh)

E-mail: antipensky@yandex.ru

A.P. Alimov − Research Scientist,

Military Educational-Scientific Center of Air Forces 

of the «Military-air academy named after professor N.E. Zhukovsky and Yu.A. Gagarin» (Voronezh) E-mail: alimov21@mail.ru

Formulation of the problem. When designing the analog part of the radio receiving path of modern electronic equipment the stability and robustness of frequency characteristics are provided through the use of highly stable electronic components. With that, the choice of a method for approximating the transfer functions of filter device is not taken into account. Method for approximating the required frequency characteristics are based on the well-known solutions of Butterworth, Chebyshev, inverse Chebyshev and Zolotarev polynomials in the normalized frequency region of the filer-prototype. The essence of the choice of an approximation method consists in estimating the robustness of polynomials to their coefficients deviations and then solving the task of reproducing the required characteristics of the realizable transfer function. The stability transfer functions of higher order filter device has not yet been evaluated. Therefore, the problem of developing a method for estimating the stability of transfers functions of higher order bandpass devices approximated by the known methods is still urgent.

In this paper, it is proposed to determine the stability coefficient of the circuits transfer function as a value inverse to the sensitivity function of the same circuit. The dependence of the stability coefficient upon the order of approximating polynomial and the location of the roots on the real-imaginary plane are obtained. Quantitative characteristics of the stability of transfer functions of higher order bandpass devices are determined. It is found that the polynomials whose roots are located, at the same time, as for as possible to the real axis and as close as possible to the real axis on the real-imaginary plane are more stable.

The obtained results can be used to refine the electronic component tolerances when designing high-order bandpass devices with due regard for the required parameters intended to be used in severe operating and environmental conditions.

Antipensky R.V., Alimov A.P. Methodology for assessing sustainability of polynomials for approximating the frequency characteristics of higher order bandpass devices. Radiotekhnika. 2020. V. 84. № 9(17). P. 58−63.  DOI: 10.18127/j00338486-202009(17)-05.

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