Curve-fitting method for transfer function determination

A curve-fitting method for determination of transfer functions by frequency sweep analysis is established. The method uses linearization of the modeled signals by use of a Taylors series and minimization of the error between the estimated and the measured values by the least-squares method. It is found that the transfer function determined by this method is more certain and stable than it would be if the transfer function were determined by detecting maximum amplitudes and zero-crossings of the input/output signals even if these signals had been averaged and filtered. Some errors are detected in the phase angles at very low currents, but the errors are within ±30 degrees