Industrial Automatic Control Systems and Controllers Annotation << Back Error Comparative Analysis of Two Spectral Differentiation Methods S.N. Sazonov The article analyzes the errors of two methods for estimating the derivatives of the current-voltage characteristics of nonlinear objects based on the signal spectrum. The fi rst method is based on the registration of higher harmonics when an object is exposed to a harmonic test signal. The second method records the spectrum obtained using the fast Fourier transform when the object is exposed to a biharmonic test signal. The accuracy of the evaluation of the derivative voltampere characteristics was verifi ed using examples of two models of typical electronic units. Both models are examples of nonlinear objects. The Spectrum Micro-Cap12 circuit simulation program was used as a testing tool. Based on the results of the test, it was established that the use of the second method for estimating the derivatives of the voltampere characteristics of nonlinear objects gives a smaller error. In addition, the selection of the response signal in the second method is much easier to implement from a technical point of view. Keywords: current-voltage characteristic, derivative calculation, response signal spectrum, electronics node models, Micro-Cap12 simulation. DOI: 10.25791/asu.12.2024.1552 Pp. 39-46.