Correction of Nonlinear Distortions of Signals in Ultrawideband Devices Using Their Model in the Form of a Nonlinear Recursive Filter

Abstract

A method for correcting dynamical nonlinear distortions introduced by ultrawideband devices in various measuring paths is considered. Devices with an operating frequency range comparable to the center frequency of the range (the absolute frequencies may vary) are considered to be ultrawideband. The method is based on characterizing the device using a set of step responses and replacing this device with an equivalent circuit containing nonlinear resistive and reactive elements. The characteristics of these elements are selected so that this circuit has step responses close to the step responses of the device. Using the equivalent circuit, the device input signals are found from the specified output signals, i.e., the problem of synthesizing an operator with properties inverse to the properties of the object (corrector synthesis) is solved. The used device model functionally corresponds to a nonlinear recursive filter and imposes no restrictions on the shape and bandwidth of the signals under correction. An approach to regularizing the correction procedure to reduce the influence of noise, interference, and systematic errors is considered. Using a baseband pulse power amplifier as an example, it is shown that the static nonlinearity decreases from 16 to 1.4%, and the dynamic nonlinearity is reduced from 44 to 3%.